@ -4,6 +4,7 @@
@@ -4,6 +4,7 @@
* See accompanying file LICENSE.txt or copy at
* https://opensource.org/licenses/MIT
***/
#ifndef SHA1DC_SHA1_H
#define SHA1DC_SHA1_H
@ -11,36 +12,30 @@
@@ -11,36 +12,30 @@
extern "C" {
#endif
/* uses SHA-1 message expansion to expand the first 16 words of W[] to 80 words */
/* void sha1_message_expansion(uint32_t W[80]); */
/* sha-1 compression function; first version takes a message block pre-parsed as 16 32-bit integers, second version takes an already expanded message) */
/* void sha1_compression(uint32_t ihv[5], const uint32_t m[16]);
void sha1_compression_W(uint32_t ihv[5], const uint32_t W[80]); */
#ifndef SHA1DC_NO_STANDARD_INCLUDES
#include <stdint.h>
#endif
/* same as sha1_compression_W, but additionally store intermediate states */
/* sha-1 compression function that takes an already expanded message, and additionally store intermediate states */
/* only stores states ii (the state between step ii-1 and step ii) when DOSTORESTATEii is defined in ubc_check.h */
void sha1_compression_states(uint32_t[5], const uint32_t[16], uint32_t[80], uint32_t[80][5]);
/*
// 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])
// where 0 <= T < 80
// me2 is an expanded message (the expansion of an original message block XOR'ed with a disturbance vector's message block difference)
// 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
// the function will return:
// ihvin: the reconstructed input chaining value
// ihvout: the reconstructed output chaining value
// 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]).
// Where 0 <= T < 80
// me2 is an expanded message (the expansion of an original message block XOR'ed with a disturbance vector's message block difference.)
// 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.
// The function will return:
// ihvin: The reconstructed input chaining value.
// ihvout: The reconstructed output chaining value.
*/
typedef void(*sha1_recompression_type)(uint32_t*, uint32_t*, const uint32_t*, const uint32_t*);
/* table of sha1_recompression_step_0, ... , sha1_recompression_step_79 */
/* extern sha1_recompression_type sha1_recompression_step[80];*/
/* a callback function type that can be set to be called when a collision block has been found: */
/* A callback function type that can be set to be called when a collision block has been found: */
/* 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]) */
typedef void(*collision_block_callback)(uint64_t, const uint32_t*, const uint32_t*, const uint32_t*, const uint32_t*);
/* the SHA-1 context */
/* The SHA-1 context. */
typedef struct {
uint64_t total;
uint32_t ihv[5];
@ -59,30 +54,34 @@ typedef struct {
@@ -59,30 +54,34 @@ typedef struct {
uint32_t states[80][5];
} SHA1_CTX;
/* initialize SHA-1 context */
/* Initialize SHA-1 context. */
void SHA1DCInit(SHA1_CTX*);
/*
// function to enable safe SHA-1 hashing:
// collision attacks are thwarted by hashing a detected near-collision block 3 times
// think of it as extending SHA-1 from 80-steps to 240-steps for such blocks:
// the best collision attacks against SHA-1 have complexity about 2^60,
// thus for 240-steps an immediate lower-bound for the best cryptanalytic attacks would 2^180
// an attacker would be better off using a generic birthday search of complexity 2^80
//
// enabling safe SHA-1 hashing will result in the correct SHA-1 hash for messages where no collision attack was detected
// but it will result in a different SHA-1 hash for messages where a collision attack was detected
// this will automatically invalidate SHA-1 based digital signature forgeries
// enabled by default
Function to enable safe SHA-1 hashing:
Collision attacks are thwarted by hashing a detected near-collision block 3 times.
Think of it as extending SHA-1 from 80-steps to 240-steps for such blocks:
The best collision attacks against SHA-1 have complexity about 2^60,
thus for 240-steps an immediate lower-bound for the best cryptanalytic attacks would be 2^180.
An attacker would be better off using a generic birthday search of complexity 2^80.
Enabling safe SHA-1 hashing will result in the correct SHA-1 hash for messages where no collision attack was detected,
but it will result in a different SHA-1 hash for messages where a collision attack was detected.
This will automatically invalidate SHA-1 based digital signature forgeries.
Enabled by default.
*/
void SHA1DCSetSafeHash(SHA1_CTX*, int);
/* function to disable or enable the use of Unavoidable Bitconditions (provides a significant speed up) */
/* enabled by default */
/*
Function to disable or enable the use of Unavoidable Bitconditions (provides a significant speed up).
Enabled by default
*/
void SHA1DCSetUseUBC(SHA1_CTX*, int);
/* function to disable or enable the use of Collision Detection */
/* enabled by default */
/*
Function to disable or enable the use of Collision Detection.
Enabled by default.
*/
void SHA1DCSetUseDetectColl(SHA1_CTX*, int);
/* function to disable or enable the detection of reduced-round SHA-1 collisions */
@ -100,23 +99,12 @@ void SHA1DCUpdate(SHA1_CTX*, const char*, size_t);
@@ -100,23 +99,12 @@ void SHA1DCUpdate(SHA1_CTX*, const char*, size_t);
/* returns: 0 = no collision detected, otherwise = collision found => warn user for active attack */
int SHA1DCFinal(unsigned char[20], SHA1_CTX*);
/*
* Same as SHA1DCFinal, but convert collision attack case into a verbose die().
*/
void git_SHA1DCFinal(unsigned char [20], SHA1_CTX *);
/*
* Same as SHA1DCUpdate, but adjust types to match git's usual interface.
*/
void git_SHA1DCUpdate(SHA1_CTX *ctx, const void *data, unsigned long len);
#define platform_SHA_CTX SHA1_CTX
#define platform_SHA1_Init SHA1DCInit
#define platform_SHA1_Update git_SHA1DCUpdate
#define platform_SHA1_Final git_SHA1DCFinal
#if defined(__cplusplus)
}
#endif
#endif /* SHA1DC_SHA1_H */
#ifdef SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H
#include SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H
#endif
#endif
Junio C Hamano
8 years ago