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are the dictionary elements randomly placed?

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Alvaro Cuno

are the dictionary elements randomly placed?

Hello all,

I signed a same file (hello.pdf) three times using the next code:

public static void sign(String src, String dest)

throws IOException, DocumentException, KeyStoreException,

NoSuchAlgorithmException, CertificateException, UnrecoverableKeyException {

Security.addProvider(new BouncyCastleProvider());

KeyStore ks = KeyStore.getInstance("pkcs12");

ks.load(new FileInputStream("citizen1.p12"), "password".toCharArray());

String alias = (String) ks.aliases().nextElement();

PrivateKey key = (PrivateKey) ks.getKey(alias, "password".toCharArray());

Certificate[] chain = ks.getCertificateChain(alias);

PdfReader reader = new PdfReader(src);

FileOutputStream os = new FileOutputStream(dest);

PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0', null, true);

PdfSignatureAppearance appearance = stamper.getSignatureAppearance();

appearance.setAcro6Layers(true);

appearance.setCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);

appearance.setVisibleSignature(new Rectangle(160, 732, 232, 780), 1, null);

Calendar cal = Calendar.getInstance();

cal.setTime(new Date(0));

appearance.setSignDate(cal);

stamper.close();

}

Everything is ok and all digital signatures are valid, however I don't understand why the internal structures of the signed documents (see attached files) are different?

hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf

... ... ...

%%EOF %%EOF %%EOF

... ... ...

10 0 obj 10 0 obj 10 0 obj

11 0 obj 8 0 obj 11 0 obj

12 0 obj 11 0 obj 12 0 obj

8 0 obj 9 0 obj 9 0 obj

9 0 obj 12 0 obj 8 0 obj

5 0 obj 5 0 obj 5 0 obj

... ... ...

The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ... these were inserted randomly? if yes, why?

Alvaro

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threat landscape has changed and how IT managers can respond. Discussions
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_______________________________________________
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iText(R) is a registered trademark of 1T3XT BVBA.
Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

hello-signed-1.pdf (17K) Download Attachment

hello-signed-2.pdf (17K) Download Attachment

hello-signed-3.pdf (17K) Download Attachment

hello.pdf (1K) Download Attachment

Leonard Rosenthol-3

Re: are the dictionary elements randomly placed?

Because object numbering and their location in a PDF are completely free form – there are no requirements.

Why does it matter?

From: Alvaro Cuno <[hidden email]>
Reply-To: Post here <[hidden email]>
To: Post here <[hidden email]>
Subject: [iText-questions] are the dictionary elements randomly placed?

Hello all,

I signed a same file (hello.pdf) three times using the next code:

public static void sign(String src, String dest)

throws IOException, DocumentException, KeyStoreException,

NoSuchAlgorithmException, CertificateException, UnrecoverableKeyException {

Security.addProvider(new BouncyCastleProvider());

KeyStore ks = KeyStore.getInstance("pkcs12");

ks.load(new FileInputStream("citizen1.p12"), "password".toCharArray());

String alias = (String) ks.aliases().nextElement();

PrivateKey key = (PrivateKey) ks.getKey(alias, "password".toCharArray());

Certificate[] chain = ks.getCertificateChain(alias);

PdfReader reader = new PdfReader(src);

FileOutputStream os = new FileOutputStream(dest);

PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0', null, true);

PdfSignatureAppearance appearance = stamper.getSignatureAppearance();

appearance.setAcro6Layers(true);

appearance.setCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);

appearance.setVisibleSignature(new Rectangle(160, 732, 232, 780), 1, null);

Calendar cal = Calendar.getInstance();

cal.setTime(new Date(0));

appearance.setSignDate(cal);

stamper.close();

}

Everything is ok and all digital signatures are valid, however I don't understand why the internal structures of the signed documents (see attached files) are different?

hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf

... ... ...

%%EOF %%EOF %%EOF

... ... ...

10 0 obj 10 0 obj 10 0 obj

11 0 obj 8 0 obj 11 0 obj

12 0 obj 11 0 obj 12 0 obj

8 0 obj 9 0 obj 9 0 obj

9 0 obj 12 0 obj 8 0 obj

5 0 obj 5 0 obj 5 0 obj

... ... ...

The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ... these were inserted randomly? if yes, why?

Alvaro

iText Mailing List

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Op 10/09/2012 1:29, Alvaro Cuno schreef:
> Everything is ok and all digital signatures are valid, however I don't
> understand why the internal structures of the signed documents (see
> attached files) are different?
1. You're not using the most recent version of iText; the type of
signature you're using will be deprecated in PDF 2.0. ISO-32000-2
recommends: “To support backward compatibility, PDF readers should
process this value for the /SubFilter key but PDF writers shall not use
this value for that key.” Please upgrade to the latest iText version and
use a different type of signature.
2. The only thing you need to know, is this: you're using bad software
if you're able to produce two binary identical PDF files by running the
same program twice. Object numbers shouldn't matter.

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and
threat landscape has changed and how IT managers can respond. Discussions
will include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
iText-questions mailing list
[hidden email]
https://lists.sourceforge.net/lists/listinfo/itext-questions

iText(R) is a registered trademark of 1T3XT BVBA.
Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: are the dictionary elements randomly placed?

In reply to this post by Leonard Rosenthol-3

Ok, if not is a pdf standard requirement, how can I set the fixed form
instead of the free form? that is it possible? ... I noticed the fact
because I was experimenting implement digital signatures using
multiple machines so I can use only local variables.

Greats
-
Alvaro

On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]> wrote:

> Because object numbering and their location in a PDF are completely free
> form – there are no requirements.
>
> Why does it matter?
>
> From: Alvaro Cuno <[hidden email]>
> Reply-To: Post here <[hidden email]>
> To: Post here <[hidden email]>
> Subject: [iText-questions] are the dictionary elements randomly placed?
>
>
> Hello all,
>
> I signed a same file (hello.pdf) three times using the next code:
>
> public static void sign(String src, String dest)
> throws IOException, DocumentException, KeyStoreException,
> NoSuchAlgorithmException, CertificateException,
> UnrecoverableKeyException {
>
> Security.addProvider(new BouncyCastleProvider());
> KeyStore ks = KeyStore.getInstance("pkcs12");
> ks.load(new FileInputStream("citizen1.p12"),
> "password".toCharArray());
> String alias = (String) ks.aliases().nextElement();
> PrivateKey key = (PrivateKey) ks.getKey(alias,
> "password".toCharArray());
> Certificate[] chain = ks.getCertificateChain(alias);
>
> PdfReader reader = new PdfReader(src);
> FileOutputStream os = new FileOutputStream(dest);
> PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0',
> null, true);
> PdfSignatureAppearance appearance =
> stamper.getSignatureAppearance();
> appearance.setAcro6Layers(true);
> appearance.setCrypto(key, chain, null,
> PdfSignatureAppearance.WINCER_SIGNED);
> appearance.setVisibleSignature(new Rectangle(160, 732, 232, 780), 1,
> null);
> Calendar cal = Calendar.getInstance();
> cal.setTime(new Date(0));
> appearance.setSignDate(cal);
> stamper.close();
> }
>
> Everything is ok and all digital signatures are valid, however I don't
> understand why the internal structures of the signed documents (see attached
> files) are different?
>
>
> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
> ... ... ...
> %%EOF %%EOF %%EOF
> ... ... ...
> 10 0 obj 10 0 obj 10 0 obj
> 11 0 obj 8 0 obj 11 0 obj
> 12 0 obj 11 0 obj 12 0 obj
> 8 0 obj 9 0 obj 9 0 obj
> 9 0 obj 12 0 obj 8 0 obj
> 5 0 obj 5 0 obj 5 0 obj
> ... ... ...
>
>
> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ... these
> were inserted randomly? if yes, why?
>
> -
> Alvaro
>
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a
> reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples:
> http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: are the dictionary elements randomly placed?

In reply to this post by iText Mailing List

Thanks for your quick answer. I agree the first point, however the
second one it is not clear for me yet. I suppose it is for security
reasons. Would you said me what risks are mitigated with that feature?

Regards

-
Alvaro

On 10 September 2012 02:05, iText Info <[hidden email]> wrote:

> Op 10/09/2012 1:29, Alvaro Cuno schreef:
>> Everything is ok and all digital signatures are valid, however I don't
>> understand why the internal structures of the signed documents (see
>> attached files) are different?
> 1. You're not using the most recent version of iText; the type of
> signature you're using will be deprecated in PDF 2.0. ISO-32000-2
> recommends: “To support backward compatibility, PDF readers should
> process this value for the /SubFilter key but PDF writers shall not use
> this value for that key.” Please upgrade to the latest iText version and
> use a different type of signature.
> 2. The only thing you need to know, is this: you're using bad software
> if you're able to produce two binary identical PDF files by running the
> same program twice. Object numbers shouldn't matter.
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

mkl

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Alvaro,

Alvaro Cuno wrote

I noticed the fact because I was experimenting implement digital signatures using
multiple machines so I can use only local variables.

You will soon see that there are more differences than just the order of objects: dates and ids especially.

Please search the archives for "deferred signing".each time you create a stamper for signing, the hash of the bytes to sign is different. Some ideas on how to get around this problem have been presented on this list.

Regards, Michael

Leonard Rosenthol-3

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Neither iText nor any other PDF producer has such an option, because it
serves no useful purpose.

I still don't understand why it matters since the PDF is valid and
processes correctly.

Leonard

On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:

>Ok, if not is a pdf standard requirement, how can I set the fixed form
>instead of the free form? that is it possible? ... I noticed the fact
>because I was experimenting implement digital signatures using
>multiple machines so I can use only local variables.
>
>Greats
>-
>Alvaro
>
>
>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]> wrote:
>> Because object numbering and their location in a PDF are completely free
>> form there are no requirements.
>>
>> Why does it matter?
>>
>> From: Alvaro Cuno <[hidden email]>
>> Reply-To: Post here <[hidden email]>
>> To: Post here <[hidden email]>
>> Subject: [iText-questions] are the dictionary elements randomly placed?
>>
>>
>> Hello all,
>>
>> I signed a same file (hello.pdf) three times using the next code:
>>
>> public static void sign(String src, String dest)
>> throws IOException, DocumentException, KeyStoreException,
>> NoSuchAlgorithmException, CertificateException,
>> UnrecoverableKeyException {
>>
>> Security.addProvider(new BouncyCastleProvider());
>> KeyStore ks = KeyStore.getInstance("pkcs12");
>> ks.load(new FileInputStream("citizen1.p12"),
>> "password".toCharArray());
>> String alias = (String) ks.aliases().nextElement();
>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>> "password".toCharArray());
>> Certificate[] chain = ks.getCertificateChain(alias);
>>
>> PdfReader reader = new PdfReader(src);
>> FileOutputStream os = new FileOutputStream(dest);
>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>'\0',
>> null, true);
>> PdfSignatureAppearance appearance =
>> stamper.getSignatureAppearance();
>> appearance.setAcro6Layers(true);
>> appearance.setCrypto(key, chain, null,
>> PdfSignatureAppearance.WINCER_SIGNED);
>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>780), 1,
>> null);
>> Calendar cal = Calendar.getInstance();
>> cal.setTime(new Date(0));
>> appearance.setSignDate(cal);
>> stamper.close();
>> }
>>
>> Everything is ok and all digital signatures are valid, however I don't
>> understand why the internal structures of the signed documents (see
>>attached
>> files) are different?
>>
>>
>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>> ... ... ...
>> %%EOF %%EOF %%EOF
>> ... ... ...
>> 10 0 obj 10 0 obj 10 0 obj
>> 11 0 obj 8 0 obj 11 0 obj
>> 12 0 obj 11 0 obj 12 0 obj
>> 8 0 obj 9 0 obj 9 0 obj
>> 9 0 obj 12 0 obj 8 0 obj
>> 5 0 obj 5 0 obj 5 0 obj
>> ... ... ...
>>
>>
>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ... these
>> were inserted randomly? if yes, why?
>>
>> -
>> Alvaro
>>
>>
>>
>>-------------------------------------------------------------------------
>>-----
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond.
>>Discussions
>> will include endpoint security, mobile security and the latest in
>>malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> iText-questions mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
>> Many questions posted to this list can (and will) be answered with a
>> reference to the iText book: http://www.itextpdf.com/book/
>> Please check the keywords list before you ask for examples:
>> http://itextpdf.com/themes/keywords.php
>
>--------------------------------------------------------------------------
>----
>Live Security Virtual Conference
>Exclusive live event will cover all the ways today's security and
>threat landscape has changed and how IT managers can respond. Discussions
>will include endpoint security, mobile security and the latest in malware
>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>_______________________________________________
>iText-questions mailing list
>[hidden email]
>https://lists.sourceforge.net/lists/listinfo/itext-questions
>
>iText(R) is a registered trademark of 1T3XT BVBA.
>Many questions posted to this list can (and will) be answered with a
>reference to the iText book: http://www.itextpdf.com/book/
>Please check the keywords list before you ask for examples:
>http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by mkl

Hello Michel, thanks, I found some discussions about deferred signing:

http://itext-general.2136553.n4.nabble.com/How-to-get-same-hash-again-td4649641.html
http://itext-general.2136553.n4.nabble.com/Sign-with-external-hash-td3086546.html#a3088565
http://itext-general.2136553.n4.nabble.com/Hash-computation-problem-td2158378.html

Certainly, the FileID and the ModDate are mentioned but nothing about
the order of the objects is discussed. Where I can read about that? Is
this documented?

-
Alvaro

On 10 September 2012 23:57, mkl <[hidden email]> wrote:

> Alvaro,
>
> Alvaro Cuno wrote
>> I noticed the fact because I was experimenting implement digital
>> signatures using
>> multiple machines so I can use only local variables.
>
> You will soon see that there are more differences than just the order of
> objects: dates and ids especially.
>
> Please search the archives for "deferred signing".each time you create a
> stamper for signing, the hash of the bytes to sign is different. Some ideas
> on how to get around this problem have been presented on this list.
>
> Regards, Michael
>
>
>
> --
> View this message in context: http://itext-general.2136553.n4.nabble.com/are-the-dictionary-elements-randomly-placed-tp4656235p4656255.html
> Sent from the iText - General mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: are the dictionary elements randomly placed?

In reply to this post by Leonard Rosenthol-3

Hello, a useful example is on deferred signing ...

Alvaro

On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]> wrote:

> Neither iText nor any other PDF producer has such an option, because it
> serves no useful purpose.
>
> I still don't understand why it matters since the PDF is valid and
> processes correctly.
>
> Leonard
>
> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>
>>Ok, if not is a pdf standard requirement, how can I set the fixed form
>>instead of the free form? that is it possible? ... I noticed the fact
>>because I was experimenting implement digital signatures using
>>multiple machines so I can use only local variables.
>>
>>Greats
>>-
>>Alvaro
>>
>>
>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]> wrote:
>>> Because object numbering and their location in a PDF are completely free
>>> form there are no requirements.
>>>
>>> Why does it matter?
>>>
>>> From: Alvaro Cuno <[hidden email]>
>>> Reply-To: Post here <[hidden email]>
>>> To: Post here <[hidden email]>
>>> Subject: [iText-questions] are the dictionary elements randomly placed?
>>>
>>>
>>> Hello all,
>>>
>>> I signed a same file (hello.pdf) three times using the next code:
>>>
>>> public static void sign(String src, String dest)
>>> throws IOException, DocumentException, KeyStoreException,
>>> NoSuchAlgorithmException, CertificateException,
>>> UnrecoverableKeyException {
>>>
>>> Security.addProvider(new BouncyCastleProvider());
>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>> ks.load(new FileInputStream("citizen1.p12"),
>>> "password".toCharArray());
>>> String alias = (String) ks.aliases().nextElement();
>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>> "password".toCharArray());
>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>
>>> PdfReader reader = new PdfReader(src);
>>> FileOutputStream os = new FileOutputStream(dest);
>>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>>'\0',
>>> null, true);
>>> PdfSignatureAppearance appearance =
>>> stamper.getSignatureAppearance();
>>> appearance.setAcro6Layers(true);
>>> appearance.setCrypto(key, chain, null,
>>> PdfSignatureAppearance.WINCER_SIGNED);
>>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>>780), 1,
>>> null);
>>> Calendar cal = Calendar.getInstance();
>>> cal.setTime(new Date(0));
>>> appearance.setSignDate(cal);
>>> stamper.close();
>>> }
>>>
>>> Everything is ok and all digital signatures are valid, however I don't
>>> understand why the internal structures of the signed documents (see
>>>attached
>>> files) are different?
>>>
>>>
>>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>>> ... ... ...
>>> %%EOF %%EOF %%EOF
>>> ... ... ...
>>> 10 0 obj 10 0 obj 10 0 obj
>>> 11 0 obj 8 0 obj 11 0 obj
>>> 12 0 obj 11 0 obj 12 0 obj
>>> 8 0 obj 9 0 obj 9 0 obj
>>> 9 0 obj 12 0 obj 8 0 obj
>>> 5 0 obj 5 0 obj 5 0 obj
>>> ... ... ...
>>>
>>>
>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ... these
>>> were inserted randomly? if yes, why?
>>>
>>> -
>>> Alvaro
>>>
>>>
>>>
>>>-------------------------------------------------------------------------
>>>-----
>>> Live Security Virtual Conference
>>> Exclusive live event will cover all the ways today's security and
>>> threat landscape has changed and how IT managers can respond.
>>>Discussions
>>> will include endpoint security, mobile security and the latest in
>>>malware
>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>> _______________________________________________
>>> iText-questions mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>> Many questions posted to this list can (and will) be answered with a
>>> reference to the iText book: http://www.itextpdf.com/book/
>>> Please check the keywords list before you ask for examples:
>>> http://itextpdf.com/themes/keywords.php
>>
>>--------------------------------------------------------------------------
>>----
>>Live Security Virtual Conference
>>Exclusive live event will cover all the ways today's security and
>>threat landscape has changed and how IT managers can respond. Discussions
>>will include endpoint security, mobile security and the latest in malware
>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>_______________________________________________
>>iText-questions mailing list
>>[hidden email]
>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>>iText(R) is a registered trademark of 1T3XT BVBA.
>>Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>>Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Leonard Rosenthol-3

Re: are the dictionary elements randomly placed?

Deferred signing doesn't care about the order of the objects….

People have been implementing such for over a decade w/o any problems….

Leonard

On 9/12/12 6:00 AM, "Alvaro Cuno" <[hidden email]> wrote:

>Hello, a useful example is on deferred signing ...
>
>Alvaro
>
>On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]> wrote:
>> Neither iText nor any other PDF producer has such an option, because it
>> serves no useful purpose.
>>
>> I still don't understand why it matters since the PDF is valid and
>> processes correctly.
>>
>> Leonard
>>
>> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>
>>>Ok, if not is a pdf standard requirement, how can I set the fixed form
>>>instead of the free form? that is it possible? ... I noticed the fact
>>>because I was experimenting implement digital signatures using
>>>multiple machines so I can use only local variables.
>>>
>>>Greats
>>>-
>>>Alvaro
>>>
>>>
>>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]>
>>>wrote:
>>>> Because object numbering and their location in a PDF are completely
>>>>free
>>>> form there are no requirements.
>>>>
>>>> Why does it matter?
>>>>
>>>> From: Alvaro Cuno <[hidden email]>
>>>> Reply-To: Post here <[hidden email]>
>>>> To: Post here <[hidden email]>
>>>> Subject: [iText-questions] are the dictionary elements randomly
>>>>placed?
>>>>
>>>>
>>>> Hello all,
>>>>
>>>> I signed a same file (hello.pdf) three times using the next code:
>>>>
>>>> public static void sign(String src, String dest)
>>>> throws IOException, DocumentException, KeyStoreException,
>>>> NoSuchAlgorithmException, CertificateException,
>>>> UnrecoverableKeyException {
>>>>
>>>> Security.addProvider(new BouncyCastleProvider());
>>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>>> ks.load(new FileInputStream("citizen1.p12"),
>>>> "password".toCharArray());
>>>> String alias = (String) ks.aliases().nextElement();
>>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>>> "password".toCharArray());
>>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>>
>>>> PdfReader reader = new PdfReader(src);
>>>> FileOutputStream os = new FileOutputStream(dest);
>>>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>>>'\0',
>>>> null, true);
>>>> PdfSignatureAppearance appearance =
>>>> stamper.getSignatureAppearance();
>>>> appearance.setAcro6Layers(true);
>>>> appearance.setCrypto(key, chain, null,
>>>> PdfSignatureAppearance.WINCER_SIGNED);
>>>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>>>780), 1,
>>>> null);
>>>> Calendar cal = Calendar.getInstance();
>>>> cal.setTime(new Date(0));
>>>> appearance.setSignDate(cal);
>>>> stamper.close();
>>>> }
>>>>
>>>> Everything is ok and all digital signatures are valid, however I don't
>>>> understand why the internal structures of the signed documents (see
>>>>attached
>>>> files) are different?
>>>>
>>>>
>>>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>>>> ... ... ...
>>>> %%EOF %%EOF %%EOF
>>>> ... ... ...
>>>> 10 0 obj 10 0 obj 10 0 obj
>>>> 11 0 obj 8 0 obj 11 0 obj
>>>> 12 0 obj 11 0 obj 12 0 obj
>>>> 8 0 obj 9 0 obj 9 0
>>>>obj
>>>> 9 0 obj 12 0 obj 8 0 obj
>>>> 5 0 obj 5 0 obj 5 0
>>>>obj
>>>> ... ...
>>>>...
>>>>
>>>>
>>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ...
>>>>these
>>>> were inserted randomly? if yes, why?
>>>>
>>>> -
>>>> Alvaro
>>>>
>>>>
>>>>
>>>>-----------------------------------------------------------------------
>>>>--
>>>>-----
>>>> Live Security Virtual Conference
>>>> Exclusive live event will cover all the ways today's security and
>>>> threat landscape has changed and how IT managers can respond.
>>>>Discussions
>>>> will include endpoint security, mobile security and the latest in
>>>>malware
>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>> _______________________________________________
>>>> iText-questions mailing list
>>>> [hidden email]
>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>
>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>> Many questions posted to this list can (and will) be answered with a
>>>> reference to the iText book: http://www.itextpdf.com/book/
>>>> Please check the keywords list before you ask for examples:
>>>> http://itextpdf.com/themes/keywords.php
>>>
>>>------------------------------------------------------------------------
>>>--
>>>----
>>>Live Security Virtual Conference
>>>Exclusive live event will cover all the ways today's security and
>>>threat landscape has changed and how IT managers can respond.
>>>Discussions
>>>will include endpoint security, mobile security and the latest in
>>>malware
>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>_______________________________________________
>>>iText-questions mailing list
>>>[hidden email]
>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>>Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>
>>
>>-------------------------------------------------------------------------
>>-----
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond.
>>Discussions
>> will include endpoint security, mobile security and the latest in
>>malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> iText-questions mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
>> Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>> Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
>--------------------------------------------------------------------------
>----
>Live Security Virtual Conference
>Exclusive live event will cover all the ways today's security and
>threat landscape has changed and how IT managers can respond. Discussions
>will include endpoint security, mobile security and the latest in malware
>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>_______________________________________________
>iText-questions mailing list
>[hidden email]
>https://lists.sourceforge.net/lists/listinfo/itext-questions
>
>iText(R) is a registered trademark of 1T3XT BVBA.
>Many questions posted to this list can (and will) be answered with a
>reference to the iText book: http://www.itextpdf.com/book/
>Please check the keywords list before you ask for examples:
>http://itextpdf.com/themes/keywords.php

mkl

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Alvaro,

Alvaro Cuno wrote

I found some discussions about deferred signing:

Ok. So you do have some hints on how to continue.

Alvaro Cuno wrote

Certainly, the FileID and the ModDate are mentioned but nothing about the order of the objects is discussed. Where I can read about that? Is this documented?

More to the point: iText nowhere promisses or documents that running the same code produces PDFs with identical object IDs and identical order of objects. So why should it be expected to do so?

I have not yet noticed different orders of objects myself, but as I have not expected the order to be a constant, I might simply have overlooked it. It after all is irrelevant...

In my opinion you should try and check your use case. If I understand you correctly, you want to calculate the digest value of the document byte ranges to sign on one machine A, send that digest somewhere for signing, and receive the signature on yet another machine B to combine it with the original, unprocessed PDF.

As stated in the postings to this mailing list you already found, simply starting the integrated signing process independently on machines A and B does not work as long as you want to use an unpatched iText.

If those processes have to be separated that far, you instead have to store the result of the unfinished signing process (after maybe marking the signature value placeholder in some unique way) on machine A to some storage accessible from machine B, and on machine B you later have to insert the retrieved signature into that unfinished result.

On this mailing list Andreas Kühne numerous times pointed to an implementation of that process.

You actually can optimize that process somewhat: If signing in append mode, you only need to place the appended bytes into that storage, and you can also skip the placeholder as long as you remember its position and length. This way you may be able to restrict the intermediate storage requirements.

Regards, Michael

PS: You should consider updating the iText version you use and also select a different signature type: adbe.pkcs7.sha1 is a bad choice.

Alvaro Cuno

Re: are the dictionary elements randomly placed?

In reply to this post by Leonard Rosenthol-3

Sorry, I was too brief ... let me explain more in detail my use case:

Computer1 Computer2 Computer3
o----getMetahash(pdf, params)--->o
o<---------------metahash---------------o
o-------------------------------cipher(metahash)------------->o
o<----------------------------------signature----------------------o
o-------signDoc(pdf, signature)---->o
o<-----signedPdf-------------------------o

Notice that the only one needs to know about pdf processing is
Computer2, and because it can't store any intermediate results
Computer2 need to generate the same pdf structure twice. I think the
setting before is a deferred signing because the multiple steps.

However, if the placement of objects is random then I will have to
redesign the previous scenario.

Thanks for the advice

-
Alvaro

On 12 September 2012 00:37, Leonard Rosenthol <[hidden email]> wrote:

> Deferred signing doesn't care about the order of the objects….
>
> People have been implementing such for over a decade w/o any problems….
>
> Leonard
>
> On 9/12/12 6:00 AM, "Alvaro Cuno" <[hidden email]> wrote:
>
>>Hello, a useful example is on deferred signing ...
>>
>>Alvaro
>>
>>On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]> wrote:
>>> Neither iText nor any other PDF producer has such an option, because it
>>> serves no useful purpose.
>>>
>>> I still don't understand why it matters since the PDF is valid and
>>> processes correctly.
>>>
>>> Leonard
>>>
>>> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>
>>>>Ok, if not is a pdf standard requirement, how can I set the fixed form
>>>>instead of the free form? that is it possible? ... I noticed the fact
>>>>because I was experimenting implement digital signatures using
>>>>multiple machines so I can use only local variables.
>>>>
>>>>Greats
>>>>-
>>>>Alvaro
>>>>
>>>>
>>>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]>
>>>>wrote:
>>>>> Because object numbering and their location in a PDF are completely
>>>>>free
>>>>> form there are no requirements.
>>>>>
>>>>> Why does it matter?
>>>>>
>>>>> From: Alvaro Cuno <[hidden email]>
>>>>> Reply-To: Post here <[hidden email]>
>>>>> To: Post here <[hidden email]>
>>>>> Subject: [iText-questions] are the dictionary elements randomly
>>>>>placed?
>>>>>
>>>>>
>>>>> Hello all,
>>>>>
>>>>> I signed a same file (hello.pdf) three times using the next code:
>>>>>
>>>>> public static void sign(String src, String dest)
>>>>> throws IOException, DocumentException, KeyStoreException,
>>>>> NoSuchAlgorithmException, CertificateException,
>>>>> UnrecoverableKeyException {
>>>>>
>>>>> Security.addProvider(new BouncyCastleProvider());
>>>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>>>> ks.load(new FileInputStream("citizen1.p12"),
>>>>> "password".toCharArray());
>>>>> String alias = (String) ks.aliases().nextElement();
>>>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>>>> "password".toCharArray());
>>>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>>>
>>>>> PdfReader reader = new PdfReader(src);
>>>>> FileOutputStream os = new FileOutputStream(dest);
>>>>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>>>>'\0',
>>>>> null, true);
>>>>> PdfSignatureAppearance appearance =
>>>>> stamper.getSignatureAppearance();
>>>>> appearance.setAcro6Layers(true);
>>>>> appearance.setCrypto(key, chain, null,
>>>>> PdfSignatureAppearance.WINCER_SIGNED);
>>>>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>>>>780), 1,
>>>>> null);
>>>>> Calendar cal = Calendar.getInstance();
>>>>> cal.setTime(new Date(0));
>>>>> appearance.setSignDate(cal);
>>>>> stamper.close();
>>>>> }
>>>>>
>>>>> Everything is ok and all digital signatures are valid, however I don't
>>>>> understand why the internal structures of the signed documents (see
>>>>>attached
>>>>> files) are different?
>>>>>
>>>>>
>>>>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>>>>> ... ... ...
>>>>> %%EOF %%EOF %%EOF
>>>>> ... ... ...
>>>>> 10 0 obj 10 0 obj 10 0 obj
>>>>> 11 0 obj 8 0 obj 11 0 obj
>>>>> 12 0 obj 11 0 obj 12 0 obj
>>>>> 8 0 obj 9 0 obj 9 0
>>>>>obj
>>>>> 9 0 obj 12 0 obj 8 0 obj
>>>>> 5 0 obj 5 0 obj 5 0
>>>>>obj
>>>>> ... ...
>>>>>...
>>>>>
>>>>>
>>>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ...
>>>>>these
>>>>> were inserted randomly? if yes, why?
>>>>>
>>>>> -
>>>>> Alvaro
>>>>>
>>>>>
>>>>>
>>>>>-----------------------------------------------------------------------
>>>>>--
>>>>>-----
>>>>> Live Security Virtual Conference
>>>>> Exclusive live event will cover all the ways today's security and
>>>>> threat landscape has changed and how IT managers can respond.
>>>>>Discussions
>>>>> will include endpoint security, mobile security and the latest in
>>>>>malware
>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>> _______________________________________________
>>>>> iText-questions mailing list
>>>>> [hidden email]
>>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>
>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>> Many questions posted to this list can (and will) be answered with a
>>>>> reference to the iText book: http://www.itextpdf.com/book/
>>>>> Please check the keywords list before you ask for examples:
>>>>> http://itextpdf.com/themes/keywords.php
>>>>
>>>>------------------------------------------------------------------------
>>>>--
>>>>----
>>>>Live Security Virtual Conference
>>>>Exclusive live event will cover all the ways today's security and
>>>>threat landscape has changed and how IT managers can respond.
>>>>Discussions
>>>>will include endpoint security, mobile security and the latest in
>>>>malware
>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>_______________________________________________
>>>>iText-questions mailing list
>>>>[hidden email]
>>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>
>>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>>Many questions posted to this list can (and will) be answered with a
>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>Please check the keywords list before you ask for examples:
>>>>http://itextpdf.com/themes/keywords.php
>>>
>>>
>>>
>>>-------------------------------------------------------------------------
>>>-----
>>> Live Security Virtual Conference
>>> Exclusive live event will cover all the ways today's security and
>>> threat landscape has changed and how IT managers can respond.
>>>Discussions
>>> will include endpoint security, mobile security and the latest in
>>>malware
>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>> _______________________________________________
>>> iText-questions mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>> Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>> Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>--------------------------------------------------------------------------
>>----
>>Live Security Virtual Conference
>>Exclusive live event will cover all the ways today's security and
>>threat landscape has changed and how IT managers can respond. Discussions
>>will include endpoint security, mobile security and the latest in malware
>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>_______________________________________________
>>iText-questions mailing list
>>[hidden email]
>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>>iText(R) is a registered trademark of 1T3XT BVBA.
>>Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>>Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by mkl

Thanks you very much, now things are more clear for me. One last
question (I promise), the randomness of fileID, ModDate and placement
of the objects is for security reasons?

Thanks in advance.

On 12 September 2012 04:01, mkl <[hidden email]> wrote:

> Alvaro,
>
> Alvaro Cuno wrote
>> I found some discussions about deferred signing:
>
> Ok. So you do have some hints on how to continue.
>
> Alvaro Cuno wrote
>> Certainly, the FileID and the ModDate are mentioned but nothing about the
>> order of the objects is discussed. Where I can read about that? Is this
>> documented?
>
> More to the point: iText nowhere promisses or documents that running the
> same code produces PDFs with identical object IDs and identical order of
> objects. So why should it be expected to do so?
>
> I have not yet noticed different orders of objects myself, but as I have not
> expected the order to be a constant, I might simply have overlooked it. It
> after all is irrelevant...
>
> In my opinion you should try and check your use case. If I understand you
> correctly, you want to calculate the digest value of the document byte
> ranges to sign on one machine A, send that digest somewhere for signing, and
> receive the signature on yet another machine B to combine it with the
> original, unprocessed PDF.
>
> As stated in the postings to this mailing list you already found, simply
> starting the integrated signing process independently on machines A and B
> does not work as long as you want to use an unpatched iText.
>
> If those processes have to be separated that far, you instead have to store
> the result of the unfinished signing process (after maybe marking the
> signature value placeholder in some unique way) on machine A to some storage
> accessible from machine B, and on machine B you later have to insert the
> retrieved signature into that unfinished result.
>
> On this mailing list Andreas Kühne numerous times pointed to an
> implementation of that process.
>
> You actually can optimize that process somewhat: If signing in append mode,
> you only need to place the appended bytes into that storage, and you can
> also skip the placeholder as long as you remember its position and length.
> This way you may be able to restrict the intermediate storage requirements.
>
> Regards, Michael
>
> PS: You should consider updating the iText version you use and also select a
> different signature type: adbe.pkcs7.sha1 is a bad choice.
>
>
>
> --
> View this message in context: http://itext-general.2136553.n4.nabble.com/are-the-dictionary-elements-randomly-placed-tp4656235p4656285.html
> Sent from the iText - General mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Leonard Rosenthol-3

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Why would you ever want a scenario with three computers to do something as
simple as signing a file? This just seems like extreme overkill for no
practical reason.

As discussed, you will either need to cache the "prepared for signing"
file or modify the iText sources.

Leonard

On 9/13/12 5:42 AM, "Alvaro Cuno" <[hidden email]> wrote:

>Sorry, I was too brief ... let me explain more in detail my use case:
>
>Computer1 Computer2 Computer3
> o----getMetahash(pdf, params)--->o
> o<---------------metahash---------------o
> o-------------------------------cipher(metahash)------------->o
> o<----------------------------------signature----------------------o
> o-------signDoc(pdf, signature)---->o
> o<-----signedPdf-------------------------o
>
>Notice that the only one needs to know about pdf processing is
>Computer2, and because it can't store any intermediate results
>Computer2 need to generate the same pdf structure twice. I think the
>setting before is a deferred signing because the multiple steps.
>
>However, if the placement of objects is random then I will have to
>redesign the previous scenario.
>
>Thanks for the advice
>
>-
>Alvaro
>
>On 12 September 2012 00:37, Leonard Rosenthol <[hidden email]> wrote:
>> Deferred signing doesn't care about the order of the objects….
>>
>> People have been implementing such for over a decade w/o any problems….
>>
>> Leonard
>>
>> On 9/12/12 6:00 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>
>>>Hello, a useful example is on deferred signing ...
>>>
>>>Alvaro
>>>
>>>On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]>
>>>wrote:
>>>> Neither iText nor any other PDF producer has such an option, because
>>>>it
>>>> serves no useful purpose.
>>>>
>>>> I still don't understand why it matters since the PDF is valid and
>>>> processes correctly.
>>>>
>>>> Leonard
>>>>
>>>> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>>
>>>>>Ok, if not is a pdf standard requirement, how can I set the fixed form
>>>>>instead of the free form? that is it possible? ... I noticed the fact
>>>>>because I was experimenting implement digital signatures using
>>>>>multiple machines so I can use only local variables.
>>>>>
>>>>>Greats
>>>>>-
>>>>>Alvaro
>>>>>
>>>>>
>>>>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]>
>>>>>wrote:
>>>>>> Because object numbering and their location in a PDF are completely
>>>>>>free
>>>>>> form there are no requirements.
>>>>>>
>>>>>> Why does it matter?
>>>>>>
>>>>>> From: Alvaro Cuno <[hidden email]>
>>>>>> Reply-To: Post here <[hidden email]>
>>>>>> To: Post here <[hidden email]>
>>>>>> Subject: [iText-questions] are the dictionary elements randomly
>>>>>>placed?
>>>>>>
>>>>>>
>>>>>> Hello all,
>>>>>>
>>>>>> I signed a same file (hello.pdf) three times using the next code:
>>>>>>
>>>>>> public static void sign(String src, String dest)
>>>>>> throws IOException, DocumentException,
>>>>>>KeyStoreException,
>>>>>> NoSuchAlgorithmException, CertificateException,
>>>>>> UnrecoverableKeyException {
>>>>>>
>>>>>> Security.addProvider(new BouncyCastleProvider());
>>>>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>>>>> ks.load(new FileInputStream("citizen1.p12"),
>>>>>> "password".toCharArray());
>>>>>> String alias = (String) ks.aliases().nextElement();
>>>>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>>>>> "password".toCharArray());
>>>>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>>>>
>>>>>> PdfReader reader = new PdfReader(src);
>>>>>> FileOutputStream os = new FileOutputStream(dest);
>>>>>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>>>>>'\0',
>>>>>> null, true);
>>>>>> PdfSignatureAppearance appearance =
>>>>>> stamper.getSignatureAppearance();
>>>>>> appearance.setAcro6Layers(true);
>>>>>> appearance.setCrypto(key, chain, null,
>>>>>> PdfSignatureAppearance.WINCER_SIGNED);
>>>>>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>>>>>780), 1,
>>>>>> null);
>>>>>> Calendar cal = Calendar.getInstance();
>>>>>> cal.setTime(new Date(0));
>>>>>> appearance.setSignDate(cal);
>>>>>> stamper.close();
>>>>>> }
>>>>>>
>>>>>> Everything is ok and all digital signatures are valid, however I
>>>>>>don't
>>>>>> understand why the internal structures of the signed documents (see
>>>>>>attached
>>>>>> files) are different?
>>>>>>
>>>>>>
>>>>>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>>>>>> ... ...
>>>>>>...
>>>>>> %%EOF %%EOF %%EOF
>>>>>> ... ...
>>>>>>...
>>>>>> 10 0 obj 10 0 obj 10 0
>>>>>>obj
>>>>>> 11 0 obj 8 0 obj 11 0
>>>>>>obj
>>>>>> 12 0 obj 11 0 obj 12 0
>>>>>>obj
>>>>>> 8 0 obj 9 0 obj 9 0
>>>>>>obj
>>>>>> 9 0 obj 12 0 obj 8 0
>>>>>>obj
>>>>>> 5 0 obj 5 0 obj 5 0
>>>>>>obj
>>>>>> ... ...
>>>>>>...
>>>>>>
>>>>>>
>>>>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ...
>>>>>>these
>>>>>> were inserted randomly? if yes, why?
>>>>>>
>>>>>> -
>>>>>> Alvaro
>>>>>>
>>>>>>
>>>>>>
>>>>>>---------------------------------------------------------------------
>>>>>>--
>>>>>>--
>>>>>>-----
>>>>>> Live Security Virtual Conference
>>>>>> Exclusive live event will cover all the ways today's security and
>>>>>> threat landscape has changed and how IT managers can respond.
>>>>>>Discussions
>>>>>> will include endpoint security, mobile security and the latest in
>>>>>>malware
>>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>> _______________________________________________
>>>>>> iText-questions mailing list
>>>>>> [hidden email]
>>>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>>
>>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>> Many questions posted to this list can (and will) be answered with a
>>>>>> reference to the iText book: http://www.itextpdf.com/book/
>>>>>> Please check the keywords list before you ask for examples:
>>>>>> http://itextpdf.com/themes/keywords.php
>>>>>
>>>>>----------------------------------------------------------------------
>>>>>--
>>>>>--
>>>>>----
>>>>>Live Security Virtual Conference
>>>>>Exclusive live event will cover all the ways today's security and
>>>>>threat landscape has changed and how IT managers can respond.
>>>>>Discussions
>>>>>will include endpoint security, mobile security and the latest in
>>>>>malware
>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>_______________________________________________
>>>>>iText-questions mailing list
>>>>>[hidden email]
>>>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>
>>>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>Many questions posted to this list can (and will) be answered with a
>>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>>Please check the keywords list before you ask for examples:
>>>>>http://itextpdf.com/themes/keywords.php
>>>>
>>>>
>>>>
>>>>-----------------------------------------------------------------------
>>>>--
>>>>-----
>>>> Live Security Virtual Conference
>>>> Exclusive live event will cover all the ways today's security and
>>>> threat landscape has changed and how IT managers can respond.
>>>>Discussions
>>>> will include endpoint security, mobile security and the latest in
>>>>malware
>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>> _______________________________________________
>>>> iText-questions mailing list
>>>> [hidden email]
>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>
>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>> Many questions posted to this list can (and will) be answered with a
>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>> Please check the keywords list before you ask for examples:
>>>>http://itextpdf.com/themes/keywords.php
>>>
>>>------------------------------------------------------------------------
>>>--
>>>----
>>>Live Security Virtual Conference
>>>Exclusive live event will cover all the ways today's security and
>>>threat landscape has changed and how IT managers can respond.
>>>Discussions
>>>will include endpoint security, mobile security and the latest in
>>>malware
>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>_______________________________________________
>>>iText-questions mailing list
>>>[hidden email]
>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>>Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>
>>-------------------------------------------------------------------------
>>-----
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond.
>>Discussions
>> will include endpoint security, mobile security and the latest in
>>malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> iText-questions mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
>> Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>> Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
>--------------------------------------------------------------------------
>----
>Live Security Virtual Conference
>Exclusive live event will cover all the ways today's security and
>threat landscape has changed and how IT managers can respond. Discussions
>will include endpoint security, mobile security and the latest in malware
>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>_______________________________________________
>iText-questions mailing list
>[hidden email]
>https://lists.sourceforge.net/lists/listinfo/itext-questions
>
>iText(R) is a registered trademark of 1T3XT BVBA.
>Many questions posted to this list can (and will) be answered with a
>reference to the iText book: http://www.itextpdf.com/book/
>Please check the keywords list before you ask for examples:
>http://itextpdf.com/themes/keywords.php

Leonard Rosenthol-3

Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

ModDate is obvious - it's the date, so if you do something at a different
time, the value is different.

FileID uses various "random values", which also change with time or other
factors.

Object Ids and locations vary simply by design.

Leonard

On 9/13/12 5:58 AM, "Alvaro Cuno" <[hidden email]> wrote:

>Thanks you very much, now things are more clear for me. One last
>question (I promise), the randomness of fileID, ModDate and placement
>of the objects is for security reasons?
>
>Thanks in advance.
>
>
>On 12 September 2012 04:01, mkl <[hidden email]> wrote:
>> Alvaro,
>>
>> Alvaro Cuno wrote
>>> I found some discussions about deferred signing:
>>
>> Ok. So you do have some hints on how to continue.
>>
>> Alvaro Cuno wrote
>>> Certainly, the FileID and the ModDate are mentioned but nothing about
>>>the
>>> order of the objects is discussed. Where I can read about that? Is this
>>> documented?
>>
>> More to the point: iText nowhere promisses or documents that running the
>> same code produces PDFs with identical object IDs and identical order of
>> objects. So why should it be expected to do so?
>>
>> I have not yet noticed different orders of objects myself, but as I
>>have not
>> expected the order to be a constant, I might simply have overlooked it.
>>It
>> after all is irrelevant...
>>
>> In my opinion you should try and check your use case. If I understand
>>you
>> correctly, you want to calculate the digest value of the document byte
>> ranges to sign on one machine A, send that digest somewhere for
>>signing, and
>> receive the signature on yet another machine B to combine it with the
>> original, unprocessed PDF.
>>
>> As stated in the postings to this mailing list you already found, simply
>> starting the integrated signing process independently on machines A and
>>B
>> does not work as long as you want to use an unpatched iText.
>>
>> If those processes have to be separated that far, you instead have to
>>store
>> the result of the unfinished signing process (after maybe marking the
>> signature value placeholder in some unique way) on machine A to some
>>storage
>> accessible from machine B, and on machine B you later have to insert the
>> retrieved signature into that unfinished result.
>>
>> On this mailing list Andreas Kühne numerous times pointed to an
>> implementation of that process.
>>
>> You actually can optimize that process somewhat: If signing in append
>>mode,
>> you only need to place the appended bytes into that storage, and you can
>> also skip the placeholder as long as you remember its position and
>>length.
>> This way you may be able to restrict the intermediate storage
>>requirements.
>>
>> Regards, Michael
>>
>> PS: You should consider updating the iText version you use and also
>>select a
>> different signature type: adbe.pkcs7.sha1 is a bad choice.
>>
>>
>>
>> --
>> View this message in context:
>>http://itext-general.2136553.n4.nabble.com/are-the-dictionary-elements-ra
>>ndomly-placed-tp4656235p4656285.html
>> Sent from the iText - General mailing list archive at Nabble.com.
>>
>>
>>-------------------------------------------------------------------------
>>-----
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond.
>>Discussions
>> will include endpoint security, mobile security and the latest in
>>malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> iText-questions mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
>> Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>> Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
>--------------------------------------------------------------------------
>----
>Live Security Virtual Conference
>Exclusive live event will cover all the ways today's security and
>threat landscape has changed and how IT managers can respond. Discussions
>will include endpoint security, mobile security and the latest in malware
>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>_______________________________________________
>iText-questions mailing list
>[hidden email]
>https://lists.sourceforge.net/lists/listinfo/itext-questions
>
>iText(R) is a registered trademark of 1T3XT BVBA.
>Many questions posted to this list can (and will) be answered with a
>reference to the iText book: http://www.itextpdf.com/book/
>Please check the keywords list before you ask for examples:
>http://itextpdf.com/themes/keywords.php

mkl

Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

Alvaro,

Alvaro Cuno wrote

the randomness of fileID, ModDate and placement of the objects is for security reasons?

Each time you start to create a signature, you do start a new result document. Thus, the IDs by definition must differ. If those two processes didn't start at the time, the modification date must be different by definition. And the order of the object being of no relevance to the document may be random.

Regards, Michael

Alvaro Cuno

Re: are the dictionary elements randomly placed?

In reply to this post by Leonard Rosenthol-3

It seems an excessive setting but, for example, if Computer1 is a
mobile device, Computer2 is a server and Computer3 is a smartcard we
are in a real scenario.

On 13 September 2012 01:10, Leonard Rosenthol <[hidden email]> wrote:

> Why would you ever want a scenario with three computers to do something as
> simple as signing a file? This just seems like extreme overkill for no
> practical reason.
>
> As discussed, you will either need to cache the "prepared for signing"
> file or modify the iText sources.
>
> Leonard
>
> On 9/13/12 5:42 AM, "Alvaro Cuno" <[hidden email]> wrote:
>
>>Sorry, I was too brief ... let me explain more in detail my use case:
>>
>>Computer1 Computer2 Computer3
>> o----getMetahash(pdf, params)--->o
>> o<---------------metahash---------------o
>> o-------------------------------cipher(metahash)------------->o
>> o<----------------------------------signature----------------------o
>> o-------signDoc(pdf, signature)---->o
>> o<-----signedPdf-------------------------o
>>
>>Notice that the only one needs to know about pdf processing is
>>Computer2, and because it can't store any intermediate results
>>Computer2 need to generate the same pdf structure twice. I think the
>>setting before is a deferred signing because the multiple steps.
>>
>>However, if the placement of objects is random then I will have to
>>redesign the previous scenario.
>>
>>Thanks for the advice
>>
>>-
>>Alvaro
>>
>>On 12 September 2012 00:37, Leonard Rosenthol <[hidden email]> wrote:
>>> Deferred signing doesn't care about the order of the objects….
>>>
>>> People have been implementing such for over a decade w/o any problems….
>>>
>>> Leonard
>>>
>>> On 9/12/12 6:00 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>
>>>>Hello, a useful example is on deferred signing ...
>>>>
>>>>Alvaro
>>>>
>>>>On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]>
>>>>wrote:
>>>>> Neither iText nor any other PDF producer has such an option, because
>>>>>it
>>>>> serves no useful purpose.
>>>>>
>>>>> I still don't understand why it matters since the PDF is valid and
>>>>> processes correctly.
>>>>>
>>>>> Leonard
>>>>>
>>>>> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>>>
>>>>>>Ok, if not is a pdf standard requirement, how can I set the fixed form
>>>>>>instead of the free form? that is it possible? ... I noticed the fact
>>>>>>because I was experimenting implement digital signatures using
>>>>>>multiple machines so I can use only local variables.
>>>>>>
>>>>>>Greats
>>>>>>-
>>>>>>Alvaro
>>>>>>
>>>>>>
>>>>>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]>
>>>>>>wrote:
>>>>>>> Because object numbering and their location in a PDF are completely
>>>>>>>free
>>>>>>> form there are no requirements.
>>>>>>>
>>>>>>> Why does it matter?
>>>>>>>
>>>>>>> From: Alvaro Cuno <[hidden email]>
>>>>>>> Reply-To: Post here <[hidden email]>
>>>>>>> To: Post here <[hidden email]>
>>>>>>> Subject: [iText-questions] are the dictionary elements randomly
>>>>>>>placed?
>>>>>>>
>>>>>>>
>>>>>>> Hello all,
>>>>>>>
>>>>>>> I signed a same file (hello.pdf) three times using the next code:
>>>>>>>
>>>>>>> public static void sign(String src, String dest)
>>>>>>> throws IOException, DocumentException,
>>>>>>>KeyStoreException,
>>>>>>> NoSuchAlgorithmException, CertificateException,
>>>>>>> UnrecoverableKeyException {
>>>>>>>
>>>>>>> Security.addProvider(new BouncyCastleProvider());
>>>>>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>>>>>> ks.load(new FileInputStream("citizen1.p12"),
>>>>>>> "password".toCharArray());
>>>>>>> String alias = (String) ks.aliases().nextElement();
>>>>>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>>>>>> "password".toCharArray());
>>>>>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>>>>>
>>>>>>> PdfReader reader = new PdfReader(src);
>>>>>>> FileOutputStream os = new FileOutputStream(dest);
>>>>>>> PdfStamper stamper = PdfStamper.createSignature(reader, os,
>>>>>>>'\0',
>>>>>>> null, true);
>>>>>>> PdfSignatureAppearance appearance =
>>>>>>> stamper.getSignatureAppearance();
>>>>>>> appearance.setAcro6Layers(true);
>>>>>>> appearance.setCrypto(key, chain, null,
>>>>>>> PdfSignatureAppearance.WINCER_SIGNED);
>>>>>>> appearance.setVisibleSignature(new Rectangle(160, 732, 232,
>>>>>>>780), 1,
>>>>>>> null);
>>>>>>> Calendar cal = Calendar.getInstance();
>>>>>>> cal.setTime(new Date(0));
>>>>>>> appearance.setSignDate(cal);
>>>>>>> stamper.close();
>>>>>>> }
>>>>>>>
>>>>>>> Everything is ok and all digital signatures are valid, however I
>>>>>>>don't
>>>>>>> understand why the internal structures of the signed documents (see
>>>>>>>attached
>>>>>>> files) are different?
>>>>>>>
>>>>>>>
>>>>>>> hello-signed-1.pdf hello-signed-2.pdf hello-signed-3.pdf
>>>>>>> ... ...
>>>>>>>...
>>>>>>> %%EOF %%EOF %%EOF
>>>>>>> ... ...
>>>>>>>...
>>>>>>> 10 0 obj 10 0 obj 10 0
>>>>>>>obj
>>>>>>> 11 0 obj 8 0 obj 11 0
>>>>>>>obj
>>>>>>> 12 0 obj 11 0 obj 12 0
>>>>>>>obj
>>>>>>> 8 0 obj 9 0 obj 9 0
>>>>>>>obj
>>>>>>> 9 0 obj 12 0 obj 8 0
>>>>>>>obj
>>>>>>> 5 0 obj 5 0 obj 5 0
>>>>>>>obj
>>>>>>> ... ...
>>>>>>>...
>>>>>>>
>>>>>>>
>>>>>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ...
>>>>>>>these
>>>>>>> were inserted randomly? if yes, why?
>>>>>>>
>>>>>>> -
>>>>>>> Alvaro
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>---------------------------------------------------------------------
>>>>>>>--
>>>>>>>--
>>>>>>>-----
>>>>>>> Live Security Virtual Conference
>>>>>>> Exclusive live event will cover all the ways today's security and
>>>>>>> threat landscape has changed and how IT managers can respond.
>>>>>>>Discussions
>>>>>>> will include endpoint security, mobile security and the latest in
>>>>>>>malware
>>>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>>> _______________________________________________
>>>>>>> iText-questions mailing list
>>>>>>> [hidden email]
>>>>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>>>
>>>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>>> Many questions posted to this list can (and will) be answered with a
>>>>>>> reference to the iText book: http://www.itextpdf.com/book/
>>>>>>> Please check the keywords list before you ask for examples:
>>>>>>> http://itextpdf.com/themes/keywords.php
>>>>>>
>>>>>>----------------------------------------------------------------------
>>>>>>--
>>>>>>--
>>>>>>----
>>>>>>Live Security Virtual Conference
>>>>>>Exclusive live event will cover all the ways today's security and
>>>>>>threat landscape has changed and how IT managers can respond.
>>>>>>Discussions
>>>>>>will include endpoint security, mobile security and the latest in
>>>>>>malware
>>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>>_______________________________________________
>>>>>>iText-questions mailing list
>>>>>>[hidden email]
>>>>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>>
>>>>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>>Many questions posted to this list can (and will) be answered with a
>>>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>>>Please check the keywords list before you ask for examples:
>>>>>>http://itextpdf.com/themes/keywords.php
>>>>>
>>>>>
>>>>>
>>>>>-----------------------------------------------------------------------
>>>>>--
>>>>>-----
>>>>> Live Security Virtual Conference
>>>>> Exclusive live event will cover all the ways today's security and
>>>>> threat landscape has changed and how IT managers can respond.
>>>>>Discussions
>>>>> will include endpoint security, mobile security and the latest in
>>>>>malware
>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>> _______________________________________________
>>>>> iText-questions mailing list
>>>>> [hidden email]
>>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>
>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>> Many questions posted to this list can (and will) be answered with a
>>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>> Please check the keywords list before you ask for examples:
>>>>>http://itextpdf.com/themes/keywords.php
>>>>
>>>>------------------------------------------------------------------------
>>>>--
>>>>----
>>>>Live Security Virtual Conference
>>>>Exclusive live event will cover all the ways today's security and
>>>>threat landscape has changed and how IT managers can respond.
>>>>Discussions
>>>>will include endpoint security, mobile security and the latest in
>>>>malware
>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>_______________________________________________
>>>>iText-questions mailing list
>>>>[hidden email]
>>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>
>>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>>Many questions posted to this list can (and will) be answered with a
>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>Please check the keywords list before you ask for examples:
>>>>http://itextpdf.com/themes/keywords.php
>>>
>>>
>>>-------------------------------------------------------------------------
>>>-----
>>> Live Security Virtual Conference
>>> Exclusive live event will cover all the ways today's security and
>>> threat landscape has changed and how IT managers can respond.
>>>Discussions
>>> will include endpoint security, mobile security and the latest in
>>>malware
>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>> _______________________________________________
>>> iText-questions mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>> Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>> Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>--------------------------------------------------------------------------
>>----
>>Live Security Virtual Conference
>>Exclusive live event will cover all the ways today's security and
>>threat landscape has changed and how IT managers can respond. Discussions
>>will include endpoint security, mobile security and the latest in malware
>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>_______________________________________________
>>iText-questions mailing list
>>[hidden email]
>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>>iText(R) is a registered trademark of 1T3XT BVBA.
>>Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>>Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

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Alvaro Cuno

Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by Leonard Rosenthol-3

Discussions on http://itext-general.2136553.n4.nabble.com/Hash-computation-problem-td2158378.html
highlights aspects to be considered respect the FileID and ModDate
manipulation, but it can be done easily.

In reference to objects Ids and their locations, I don't have idea
where apply the patch. The PdfDictionary class doesn't have any random
method ...

On 13 September 2012 01:12, Leonard Rosenthol <[hidden email]> wrote:

> ModDate is obvious - it's the date, so if you do something at a different
> time, the value is different.
>
> FileID uses various "random values", which also change with time or other
> factors.
>
> Object Ids and locations vary simply by design.
>
> Leonard
>
>
> On 9/13/12 5:58 AM, "Alvaro Cuno" <[hidden email]> wrote:
>
>>Thanks you very much, now things are more clear for me. One last
>>question (I promise), the randomness of fileID, ModDate and placement
>>of the objects is for security reasons?
>>
>>Thanks in advance.
>>
>>
>>On 12 September 2012 04:01, mkl <[hidden email]> wrote:
>>> Alvaro,
>>>
>>> Alvaro Cuno wrote
>>>> I found some discussions about deferred signing:
>>>
>>> Ok. So you do have some hints on how to continue.
>>>
>>> Alvaro Cuno wrote
>>>> Certainly, the FileID and the ModDate are mentioned but nothing about
>>>>the
>>>> order of the objects is discussed. Where I can read about that? Is this
>>>> documented?
>>>
>>> More to the point: iText nowhere promisses or documents that running the
>>> same code produces PDFs with identical object IDs and identical order of
>>> objects. So why should it be expected to do so?
>>>
>>> I have not yet noticed different orders of objects myself, but as I
>>>have not
>>> expected the order to be a constant, I might simply have overlooked it.
>>>It
>>> after all is irrelevant...
>>>
>>> In my opinion you should try and check your use case. If I understand
>>>you
>>> correctly, you want to calculate the digest value of the document byte
>>> ranges to sign on one machine A, send that digest somewhere for
>>>signing, and
>>> receive the signature on yet another machine B to combine it with the
>>> original, unprocessed PDF.
>>>
>>> As stated in the postings to this mailing list you already found, simply
>>> starting the integrated signing process independently on machines A and
>>>B
>>> does not work as long as you want to use an unpatched iText.
>>>
>>> If those processes have to be separated that far, you instead have to
>>>store
>>> the result of the unfinished signing process (after maybe marking the
>>> signature value placeholder in some unique way) on machine A to some
>>>storage
>>> accessible from machine B, and on machine B you later have to insert the
>>> retrieved signature into that unfinished result.
>>>
>>> On this mailing list Andreas Kühne numerous times pointed to an
>>> implementation of that process.
>>>
>>> You actually can optimize that process somewhat: If signing in append
>>>mode,
>>> you only need to place the appended bytes into that storage, and you can
>>> also skip the placeholder as long as you remember its position and
>>>length.
>>> This way you may be able to restrict the intermediate storage
>>>requirements.
>>>
>>> Regards, Michael
>>>
>>> PS: You should consider updating the iText version you use and also
>>>select a
>>> different signature type: adbe.pkcs7.sha1 is a bad choice.
>>>
>>>
>>>
>>> --
>>> View this message in context:
>>>http://itext-general.2136553.n4.nabble.com/are-the-dictionary-elements-ra
>>>ndomly-placed-tp4656235p4656285.html
>>> Sent from the iText - General mailing list archive at Nabble.com.
>>>
>>>
>>>-------------------------------------------------------------------------
>>>-----
>>> Live Security Virtual Conference
>>> Exclusive live event will cover all the ways today's security and
>>> threat landscape has changed and how IT managers can respond.
>>>Discussions
>>> will include endpoint security, mobile security and the latest in
>>>malware
>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>> _______________________________________________
>>> iText-questions mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>> Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>> Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>--------------------------------------------------------------------------
>>----
>>Live Security Virtual Conference
>>Exclusive live event will cover all the ways today's security and
>>threat landscape has changed and how IT managers can respond. Discussions
>>will include endpoint security, mobile security and the latest in malware
>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>_______________________________________________
>>iText-questions mailing list
>>[hidden email]
>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>>iText(R) is a registered trademark of 1T3XT BVBA.
>>Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>>Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> iText-questions mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/itext-questions
>
> iText(R) is a registered trademark of 1T3XT BVBA.
> Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/
> Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php

Alvaro Cuno

Re: [SPAM] Re: [SPAM] Re: are the dictionary elements randomly placed?

In reply to this post by mkl

As far as I understand, ID and ModDate are regulated by the ISO PDF
specification, but the order of the object is a itext design
feature...

Regards

-
Alvaro

On 13 September 2012 10:16, mkl <[hidden email]> wrote:

> Alvaro,
>
> Alvaro Cuno wrote
>> the randomness of fileID, ModDate and placement of the objects is for
>> security reasons?
>
> Each time you start to create a signature, you do start a new result
> document. Thus, the IDs by definition must differ. If those two processes
> didn't start at the time, the modification date must be different by
> definition. And the order of the object being of no relevance to the
> document may be random.
>
> Regards, Michael
>
>
>
> --
> View this message in context: http://itext-general.2136553.n4.nabble.com/are-the-dictionary-elements-randomly-placed-tp4656235p4656317.html
> Sent from the iText - General mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
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Leonard Rosenthol-3

Re: are the dictionary elements randomly placed?

In reply to this post by Alvaro Cuno

In the mobile scenario, you simply ship the PDF up to the server where all
the work takes place - no problem.

Leonard

On 9/14/12 4:54 AM, "Alvaro Cuno" <[hidden email]> wrote:

>It seems an excessive setting but, for example, if Computer1 is a
>mobile device, Computer2 is a server and Computer3 is a smartcard we
>are in a real scenario.
>
>On 13 September 2012 01:10, Leonard Rosenthol <[hidden email]> wrote:
>> Why would you ever want a scenario with three computers to do something
>>as
>> simple as signing a file? This just seems like extreme overkill for no
>> practical reason.
>>
>> As discussed, you will either need to cache the "prepared for signing"
>> file or modify the iText sources.
>>
>> Leonard
>>
>> On 9/13/12 5:42 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>
>>>Sorry, I was too brief ... let me explain more in detail my use case:
>>>
>>>Computer1 Computer2 Computer3
>>> o----getMetahash(pdf, params)--->o
>>> o<---------------metahash---------------o
>>> o-------------------------------cipher(metahash)------------->o
>>> o<----------------------------------signature----------------------o
>>> o-------signDoc(pdf, signature)---->o
>>> o<-----signedPdf-------------------------o
>>>
>>>Notice that the only one needs to know about pdf processing is
>>>Computer2, and because it can't store any intermediate results
>>>Computer2 need to generate the same pdf structure twice. I think the
>>>setting before is a deferred signing because the multiple steps.
>>>
>>>However, if the placement of objects is random then I will have to
>>>redesign the previous scenario.
>>>
>>>Thanks for the advice
>>>
>>>-
>>>Alvaro
>>>
>>>On 12 September 2012 00:37, Leonard Rosenthol <[hidden email]>
>>>wrote:
>>>> Deferred signing doesn't care about the order of the objects….
>>>>
>>>> People have been implementing such for over a decade w/o any
>>>>problems….
>>>>
>>>> Leonard
>>>>
>>>> On 9/12/12 6:00 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>>
>>>>>Hello, a useful example is on deferred signing ...
>>>>>
>>>>>Alvaro
>>>>>
>>>>>On 11 September 2012 02:00, Leonard Rosenthol <[hidden email]>
>>>>>wrote:
>>>>>> Neither iText nor any other PDF producer has such an option, because
>>>>>>it
>>>>>> serves no useful purpose.
>>>>>>
>>>>>> I still don't understand why it matters since the PDF is valid and
>>>>>> processes correctly.
>>>>>>
>>>>>> Leonard
>>>>>>
>>>>>> On 9/11/12 5:30 AM, "Alvaro Cuno" <[hidden email]> wrote:
>>>>>>
>>>>>>>Ok, if not is a pdf standard requirement, how can I set the fixed
>>>>>>>form
>>>>>>>instead of the free form? that is it possible? ... I noticed the
>>>>>>>fact
>>>>>>>because I was experimenting implement digital signatures using
>>>>>>>multiple machines so I can use only local variables.
>>>>>>>
>>>>>>>Greats
>>>>>>>-
>>>>>>>Alvaro
>>>>>>>
>>>>>>>
>>>>>>>On 10 September 2012 01:58, Leonard Rosenthol <[hidden email]>
>>>>>>>wrote:
>>>>>>>> Because object numbering and their location in a PDF are
>>>>>>>>completely
>>>>>>>>free
>>>>>>>> form there are no requirements.
>>>>>>>>
>>>>>>>> Why does it matter?
>>>>>>>>
>>>>>>>> From: Alvaro Cuno <[hidden email]>
>>>>>>>> Reply-To: Post here <[hidden email]>
>>>>>>>> To: Post here <[hidden email]>
>>>>>>>> Subject: [iText-questions] are the dictionary elements randomly
>>>>>>>>placed?
>>>>>>>>
>>>>>>>>
>>>>>>>> Hello all,
>>>>>>>>
>>>>>>>> I signed a same file (hello.pdf) three times using the next code:
>>>>>>>>
>>>>>>>> public static void sign(String src, String dest)
>>>>>>>> throws IOException, DocumentException,
>>>>>>>>KeyStoreException,
>>>>>>>> NoSuchAlgorithmException, CertificateException,
>>>>>>>> UnrecoverableKeyException {
>>>>>>>>
>>>>>>>> Security.addProvider(new BouncyCastleProvider());
>>>>>>>> KeyStore ks = KeyStore.getInstance("pkcs12");
>>>>>>>> ks.load(new FileInputStream("citizen1.p12"),
>>>>>>>> "password".toCharArray());
>>>>>>>> String alias = (String) ks.aliases().nextElement();
>>>>>>>> PrivateKey key = (PrivateKey) ks.getKey(alias,
>>>>>>>> "password".toCharArray());
>>>>>>>> Certificate[] chain = ks.getCertificateChain(alias);
>>>>>>>>
>>>>>>>> PdfReader reader = new PdfReader(src);
>>>>>>>> FileOutputStream os = new FileOutputStream(dest);
>>>>>>>> PdfStamper stamper = PdfStamper.createSignature(reader,
>>>>>>>>os,
>>>>>>>>'\0',
>>>>>>>> null, true);
>>>>>>>> PdfSignatureAppearance appearance =
>>>>>>>> stamper.getSignatureAppearance();
>>>>>>>> appearance.setAcro6Layers(true);
>>>>>>>> appearance.setCrypto(key, chain, null,
>>>>>>>> PdfSignatureAppearance.WINCER_SIGNED);
>>>>>>>> appearance.setVisibleSignature(new Rectangle(160, 732,
>>>>>>>>232,
>>>>>>>>780), 1,
>>>>>>>> null);
>>>>>>>> Calendar cal = Calendar.getInstance();
>>>>>>>> cal.setTime(new Date(0));
>>>>>>>> appearance.setSignDate(cal);
>>>>>>>> stamper.close();
>>>>>>>> }
>>>>>>>>
>>>>>>>> Everything is ok and all digital signatures are valid, however I
>>>>>>>>don't
>>>>>>>> understand why the internal structures of the signed documents
>>>>>>>>(see
>>>>>>>>attached
>>>>>>>> files) are different?
>>>>>>>>
>>>>>>>>
>>>>>>>> hello-signed-1.pdf hello-signed-2.pdf
>>>>>>>>hello-signed-3.pdf
>>>>>>>> ... ...
>>>>>>>>...
>>>>>>>> %%EOF %%EOF %%EOF
>>>>>>>> ... ...
>>>>>>>>...
>>>>>>>> 10 0 obj 10 0 obj 10 0
>>>>>>>>obj
>>>>>>>> 11 0 obj 8 0 obj 11 0
>>>>>>>>obj
>>>>>>>> 12 0 obj 11 0 obj 12 0
>>>>>>>>obj
>>>>>>>> 8 0 obj 9 0 obj 9
>>>>>>>>0
>>>>>>>>obj
>>>>>>>> 9 0 obj 12 0 obj 8 0
>>>>>>>>obj
>>>>>>>> 5 0 obj 5 0 obj 5
>>>>>>>>0
>>>>>>>>obj
>>>>>>>> ... ...
>>>>>>>>...
>>>>>>>>
>>>>>>>>
>>>>>>>> The objects 8, 9 and 11 are related to /n0, /n2, /FRM fields, ...
>>>>>>>>these
>>>>>>>> were inserted randomly? if yes, why?
>>>>>>>>
>>>>>>>> -
>>>>>>>> Alvaro
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>-------------------------------------------------------------------
>>>>>>>>--
>>>>>>>>--
>>>>>>>>--
>>>>>>>>-----
>>>>>>>> Live Security Virtual Conference
>>>>>>>> Exclusive live event will cover all the ways today's security and
>>>>>>>> threat landscape has changed and how IT managers can respond.
>>>>>>>>Discussions
>>>>>>>> will include endpoint security, mobile security and the latest in
>>>>>>>>malware
>>>>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>>>> _______________________________________________
>>>>>>>> iText-questions mailing list
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>>>>>>>>
>>>>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>>>> Many questions posted to this list can (and will) be answered
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>>>>>>>> reference to the iText book: http://www.itextpdf.com/book/
>>>>>>>> Please check the keywords list before you ask for examples:
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>>>>>>>
>>>>>>>--------------------------------------------------------------------
>>>>>>>--
>>>>>>>--
>>>>>>>--
>>>>>>>----
>>>>>>>Live Security Virtual Conference
>>>>>>>Exclusive live event will cover all the ways today's security and
>>>>>>>threat landscape has changed and how IT managers can respond.
>>>>>>>Discussions
>>>>>>>will include endpoint security, mobile security and the latest in
>>>>>>>malware
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>>>>>>>_______________________________________________
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>>>>>>>
>>>>>>>iText(R) is a registered trademark of 1T3XT BVBA.
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>>>>>>
>>>>>>
>>>>>>
>>>>>>---------------------------------------------------------------------
>>>>>>--
>>>>>>--
>>>>>>-----
>>>>>> Live Security Virtual Conference
>>>>>> Exclusive live event will cover all the ways today's security and
>>>>>> threat landscape has changed and how IT managers can respond.
>>>>>>Discussions
>>>>>> will include endpoint security, mobile security and the latest in
>>>>>>malware
>>>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>> _______________________________________________
>>>>>> iText-questions mailing list
>>>>>> [hidden email]
>>>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>>
>>>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>> Many questions posted to this list can (and will) be answered with a
>>>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>>> Please check the keywords list before you ask for examples:
>>>>>>http://itextpdf.com/themes/keywords.php
>>>>>
>>>>>----------------------------------------------------------------------
>>>>>--
>>>>>--
>>>>>----
>>>>>Live Security Virtual Conference
>>>>>Exclusive live event will cover all the ways today's security and
>>>>>threat landscape has changed and how IT managers can respond.
>>>>>Discussions
>>>>>will include endpoint security, mobile security and the latest in
>>>>>malware
>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>_______________________________________________
>>>>>iText-questions mailing list
>>>>>[hidden email]
>>>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>>
>>>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>>>Many questions posted to this list can (and will) be answered with a
>>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>>>Please check the keywords list before you ask for examples:
>>>>>http://itextpdf.com/themes/keywords.php
>>>>
>>>>
>>>>-----------------------------------------------------------------------
>>>>--
>>>>-----
>>>> Live Security Virtual Conference
>>>> Exclusive live event will cover all the ways today's security and
>>>> threat landscape has changed and how IT managers can respond.
>>>>Discussions
>>>> will include endpoint security, mobile security and the latest in
>>>>malware
>>>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>> _______________________________________________
>>>> iText-questions mailing list
>>>> [hidden email]
>>>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>>
>>>> iText(R) is a registered trademark of 1T3XT BVBA.
>>>> Many questions posted to this list can (and will) be answered with a
>>>>reference to the iText book: http://www.itextpdf.com/book/
>>>> Please check the keywords list before you ask for examples:
>>>>http://itextpdf.com/themes/keywords.php
>>>
>>>------------------------------------------------------------------------
>>>--
>>>----
>>>Live Security Virtual Conference
>>>Exclusive live event will cover all the ways today's security and
>>>threat landscape has changed and how IT managers can respond.
>>>Discussions
>>>will include endpoint security, mobile security and the latest in
>>>malware
>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>_______________________________________________
>>>iText-questions mailing list
>>>[hidden email]
>>>https://lists.sourceforge.net/lists/listinfo/itext-questions
>>>
>>>iText(R) is a registered trademark of 1T3XT BVBA.
>>>Many questions posted to this list can (and will) be answered with a
>>>reference to the iText book: http://www.itextpdf.com/book/
>>>Please check the keywords list before you ask for examples:
>>>http://itextpdf.com/themes/keywords.php
>>
>>
>>-------------------------------------------------------------------------
>>-----
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond.
>>Discussions
>> will include endpoint security, mobile security and the latest in
>>malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> iText-questions mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/itext-questions
>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
>> Many questions posted to this list can (and will) be answered with a
>>reference to the iText book: http://www.itextpdf.com/book/
>> Please check the keywords list before you ask for examples:
>>http://itextpdf.com/themes/keywords.php
>
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