the acrobat 9.0 support AES 256 bits encryption. Does any one know what Hash function did they use to generate the encryption key? Is that SHA-256? The old AES 128 bit encryption use MD5 Hash, which only support 128 bit has value.
BTW, who know where can we get a copy of Adobe 1.8(acrobat 9.0) spec.
AES 256 bit encryption question
2008-08-13 10:57:17
My Product Information:
Reader 9.0, Unix/Linux
Reader 9.0, Unix/Linux
256 bit AES is the default encryption algorithm for Acrobat 9. SHA256 is the standard hash algorithm for signature digest. Not sure about encryption key generation. Algorithms are discussed in the Acrobat Security Administration guide available at http://www.adobe.com/go/acrobat_security. Unfortunately, the Acrobat 9 version of the document is not out yet.
Since PDF is now an ISO standard, ISO owns the specification and it is available (for sale) from ISO. The URL appears to be http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=51502 but you can just go to www.iso.org and search for standard 32000.