110 lines
4 KiB
C
110 lines
4 KiB
C
/***
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* Copyright 2017 Marc Stevens <marc@marc-stevens.nl>, Dan Shumow <danshu@microsoft.com>
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* Distributed under the MIT Software License.
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* See accompanying file LICENSE.txt or copy at
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* https://opensource.org/licenses/MIT
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***/
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#ifndef SHA1DC_SHA1_H
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#define SHA1DC_SHA1_H
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#if defined(__cplusplus)
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extern "C" {
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#endif
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#ifndef SHA1DC_NO_STANDARD_INCLUDES
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#include <stdint.h>
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#endif
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/* sha-1 compression function that takes an already expanded message, and additionally store intermediate states */
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/* only stores states ii (the state between step ii-1 and step ii) when DOSTORESTATEii is defined in ubc_check.h */
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void sha1_compression_states(uint32_t[5], const uint32_t[16], uint32_t[80], uint32_t[80][5]);
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/*
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// Function type for sha1_recompression_step_T (uint32_t ihvin[5], uint32_t ihvout[5], const uint32_t me2[80], const uint32_t state[5]).
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// Where 0 <= T < 80
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// me2 is an expanded message (the expansion of an original message block XOR'ed with a disturbance vector's message block difference.)
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// state is the internal state (a,b,c,d,e) before step T of the SHA-1 compression function while processing the original message block.
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// The function will return:
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// ihvin: The reconstructed input chaining value.
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// ihvout: The reconstructed output chaining value.
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*/
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typedef void(*sha1_recompression_type)(uint32_t*, uint32_t*, const uint32_t*, const uint32_t*);
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/* A callback function type that can be set to be called when a collision block has been found: */
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/* void collision_block_callback(uint64_t byteoffset, const uint32_t ihvin1[5], const uint32_t ihvin2[5], const uint32_t m1[80], const uint32_t m2[80]) */
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typedef void(*collision_block_callback)(uint64_t, const uint32_t*, const uint32_t*, const uint32_t*, const uint32_t*);
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/* The SHA-1 context. */
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typedef struct {
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uint64_t total;
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uint32_t ihv[5];
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unsigned char buffer[64];
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int found_collision;
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int safe_hash;
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int detect_coll;
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int ubc_check;
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int reduced_round_coll;
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collision_block_callback callback;
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uint32_t ihv1[5];
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uint32_t ihv2[5];
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uint32_t m1[80];
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uint32_t m2[80];
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uint32_t states[80][5];
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} SHA1_CTX;
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/* Initialize SHA-1 context. */
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void SHA1DCInit(SHA1_CTX*);
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/*
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Function to enable safe SHA-1 hashing:
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Collision attacks are thwarted by hashing a detected near-collision block 3 times.
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Think of it as extending SHA-1 from 80-steps to 240-steps for such blocks:
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The best collision attacks against SHA-1 have complexity about 2^60,
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thus for 240-steps an immediate lower-bound for the best cryptanalytic attacks would be 2^180.
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An attacker would be better off using a generic birthday search of complexity 2^80.
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Enabling safe SHA-1 hashing will result in the correct SHA-1 hash for messages where no collision attack was detected,
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but it will result in a different SHA-1 hash for messages where a collision attack was detected.
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This will automatically invalidate SHA-1 based digital signature forgeries.
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Enabled by default.
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*/
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void SHA1DCSetSafeHash(SHA1_CTX*, int);
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/*
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Function to disable or enable the use of Unavoidable Bitconditions (provides a significant speed up).
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Enabled by default
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*/
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void SHA1DCSetUseUBC(SHA1_CTX*, int);
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/*
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Function to disable or enable the use of Collision Detection.
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Enabled by default.
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*/
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void SHA1DCSetUseDetectColl(SHA1_CTX*, int);
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/* function to disable or enable the detection of reduced-round SHA-1 collisions */
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/* disabled by default */
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void SHA1DCSetDetectReducedRoundCollision(SHA1_CTX*, int);
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/* function to set a callback function, pass NULL to disable */
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/* by default no callback set */
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void SHA1DCSetCallback(SHA1_CTX*, collision_block_callback);
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/* update SHA-1 context with buffer contents */
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void SHA1DCUpdate(SHA1_CTX*, const char*, size_t);
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/* obtain SHA-1 hash from SHA-1 context */
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/* returns: 0 = no collision detected, otherwise = collision found => warn user for active attack */
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int SHA1DCFinal(unsigned char[20], SHA1_CTX*);
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#if defined(__cplusplus)
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}
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#endif
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#ifdef SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H
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#include SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H
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#endif
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#endif
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