Date: Tue, 5 Apr 2011 02:47:33 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: Using DES_bs On Mon, Apr 04, 2011 at 10:35:15AM -0500, Daniel Beard wrote: > 1) What's the difference between DES_bs and DES_bs_c? I assume, you ask about DES_bs.c and DES_bs_b.c, correct? These are two components of the bitslice DES implementation. In fact, DES_bs.h (the header file) includes prototypes for functions exported by both of the C files at once. DES_bs.c defines many small functions, which implement DES key setup and comparison of computed hashes against those loaded for cracking. DES_bs_b.c defines three DES_bs_crypt*() functions, of which only one is used at a time (for a given hash type). It also #include's one of the DES S-box files (nonstd.c, sboxes.c, or sboxes-s.c) and normally has the S-boxes inlined into the three functions. A primary reason for this split is that DES_bs_b.c is sometimes compiled with different optimization flags to force function inlining. This is no longer needed with __attribute__((always_inline)) on gcc 3.1+, but it was needed with older versions of gcc and it is still needed with other C compilers. Also, DES_bs_b.c grew quite large - the current version (in the CVS repository) is over 1000 lines, two thirds of which are the v*() macro definitions (different kinds of them) for use by the S-boxes. The corresponding version of DES_bs.c is under 500 lines, and it contains many small and non-redundant functions. Thus, this split helps readability, and I am considering a further split of DES_bs_b.c (move the macros into an include file). > 2) I understand how to set a salt for DES_bs, but I'm totally confused as to > how to which function or combination to use on a plaintext key. It depends on hash type. Since you mention a salt, you're probably not talking about LM hashes (which are saltless), so the functions to use are DES_bs_clear_keys(), DES_bs_set_key(), and then DES_bs_expand_keys(). See DES_bs.h (the header file) and DES_fmt.c for some usage hints. Don't forget to call DES_bs_init(0). Alexander
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