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From "Tilman Hausherr (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PDFBOX-2456) create TestSymmetricKeyEncryption.java
Date Mon, 10 Nov 2014 17:24:34 GMT

    [ https://issues.apache.org/jira/browse/PDFBOX-2456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14205031#comment-14205031
] 

Tilman Hausherr commented on PDFBOX-2456:
-----------------------------------------

Hello [~leonardr]... in the 1.7 spec, there is this in 7.6.3.4:
{quote}
c)(Security handlers of revision 3 or greater) Do the following 50 times: Take the output
from the previous MD5 hash and pass it as input into a new MD5 hash.
{quote}
at another place (7.6.3.3), it says 
{quote}
(Security handlers of revision 3 or greater) Do the following 50 times: Take the output from
the previous MD5 hash and pass the first n bytes of the output as input into a new MD5 hash,
where n is the number of bytes of the encryption key as defined by the value of the encryption
dictionary’s Length entry.
{quote}
Could you look whether this been changed in the upcoming 2.0 version? I'd suspect that the
short version is wrong. I'm having trouble with PDF files with 40bit encryption, i.e. PDFBox
claims that the owner password doesn't match although it should. When changing one line in
our code so that the key length is considered in the MD5 hash, it works.

> create TestSymmetricKeyEncryption.java
> --------------------------------------
>
>                 Key: PDFBOX-2456
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-2456
>             Project: PDFBox
>          Issue Type: Improvement
>          Components: Utilities
>    Affects Versions: 2.0.0
>         Environment: java7 debian7
>            Reporter: Ralf Hauser
>              Labels: AES256
>             Fix For: 2.0.0
>
>         Attachments: AES256.diff, TestSymmetricKeyEncryption.java, enc128bit_20141025_115145.pdf,
enc256bit_20141025_105451.pdf, preEnc_20141025_105451.pdf, preEnc_20141025_115145.pdf
>
>
> similarly to org.apache.pdfbox.encryption.TestPublicKeyEncryption, also test password
based encryption 
> 1) 128bit
> 2) 256bit AES PDFBOX-1594



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