Date: Mon, 31 Dec 2012 05:22:46 +0100 From: magnum <john.magnum@...hmail.com> To: john-dev@...ts.openwall.com Subject: Re: Formats dmg, encfs and strip crash on longer passwords On 31 Dec, 2012, at 5:03 , Dhiru Kholia <dhiru.kholia@...il.com> wrote: > On Monday 31 December 2012 09:11 AM, magnum wrote: >> I have now modified Lukas' pbkdf2-hmac-sha1 so it can handle a max. length of 64. I see we have some formats that use Gladman's derive_key() instead. This is slower. I tried changing ODF to keychain.h and pbkdf2() and got a 60% boost but I'm not sure it supports all variants (if there are any?) so I did not commit that. Gladman's function has one more parameter and I'm not sure if it matters. I also tried SXC but got no boost, no idea why. Finally, I tried ZIP but that did not even pass self-test. > > 1. AES support in ODF format required Gladman's code earlier (due to usage of longer salt / password size). This format can now be switched to newer and faster PBKDF2 code. ODF CPU format supports both Blowfish and AES encryption. I did not look at Lukas' code's salt length now but I think it handles 52 characters as-is (just adjust structs if needed). > 2. Gladman's function's extra parameter is a 2-byte verifier which is used in ZIP AES format. This extra parameter is not used by other formats. Great, then we can have the 60% boost for ODF. I can commit it, I still have it handy. Also, I just noticed I missed fixing odf-opencl. I'll fix that. > 3. SXC and no boost is a mystery. I will take a look. Tell me you did re-compile ;) Pretty sure I did. Let's hope I just screwed it up. > 4. ZIP files using AES 256-bit encryption require very long PBKDF2 output (upto 66 bytes). Can the new PBKDF2 code do this? Strangely the zip OpenCL handles this just fine! As-is, it produces 40 bytes but only 32 are used. It can output up to 40 bytes with a super trivial modification. How do they do more, another bunch of iterations? magnum
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