From dd6e81bfa4a7b9003a799cdcc4eb212ecbd93d8f Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Fri, 7 Nov 2014 15:12:31 +0100 Subject: check that word size is a multiple of 8 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- src/libkeccak/spec.h | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/libkeccak/spec.h b/src/libkeccak/spec.h index bc5f6c3..06e250b 100644 --- a/src/libkeccak/spec.h +++ b/src/libkeccak/spec.h @@ -82,6 +82,13 @@ */ #define LIBKECCAK_SPEC_ERROR_WORD_NON_2_POTENT 8 +/** + * Invalid `libkeccak_spec_t` values: `.bitrate + `.capacity` + * is a not multiple of 100, and thus the word size is not + * a multiple of 8 + */ +#define LIBKECCAK_SPEC_ERROR_WORD_MOD_8 9 + /** @@ -159,7 +166,8 @@ void libkeccak_spec_rawshake(libkeccak_spec_t* restrict spec, long x, long d) static inline __attribute__((nonnull, nothrow, unused, warn_unused_result, pure)) int libkeccak_spec_check(const libkeccak_spec_t* restrict spec) { - long state_size = spec->capacity + spec->bitrate, n_state_size; + long state_size = spec->capacity + spec->bitrate; + long word_size = state_size / 25, n_word_size; if (spec->bitrate <= 0) return LIBKECCAK_SPEC_ERROR_BITRATE_NONPOSITIVE; if (spec->bitrate % 8) return LIBKECCAK_SPEC_ERROR_BITRATE_MOD_8; if (spec->capacity <= 0) return LIBKECCAK_SPEC_ERROR_CAPACITY_NONPOSITIVE; @@ -167,12 +175,12 @@ int libkeccak_spec_check(const libkeccak_spec_t* restrict spec) if (spec->output <= 0) return LIBKECCAK_SPEC_ERROR_OUTPUT_NONPOSITIVE; if (state_size > 1600) return LIBKECCAK_SPEC_ERROR_STATE_TOO_LARGE; if (state_size % 25) return LIBKECCAK_SPEC_ERROR_STATE_MOD_25; - state_size /= 25; + if (word_size % 8) return LIBKECCAK_SPEC_ERROR_WORD_MOD_8; /* This is a portable implementation of `(x & -x) != x` which assumes * two's complement, which of course is always satisfied by GCC, but anyway... */ - n_state_size = ((~state_size) ^ (LONG_MIN & ~LONG_MAX)) + 1; - if ((state_size & n_state_size) != state_size) + n_word_size = ((~word_size) ^ (LONG_MIN & ~LONG_MAX)) + 1; + if ((word_size & n_word_size) != word_size) return LIBKECCAK_SPEC_ERROR_WORD_NON_2_POTENT; return 0; -- cgit v1.2.3-70-g09d2