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Merge branch 'ab/sha1dc-maint' into maint

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The "collision detecting" SHA-1 implementation shipped with 2.13
was quite broken on some big-endian platforms and/or platforms that
do not like unaligned fetches.  Update to the upstream code which
has already fixed these issues.

* ab/sha1dc-maint:
  sha1dc: update from upstream
This commit is contained in:
Junio C Hamano 2017-06-05 09:03:15 +09:00
commit d0506fc419
7 changed files with 173 additions and 89 deletions
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9
Makefile
View File

@ -1414,7 +1414,14 @@ else
DC_SHA1 := YesPlease
LIB_OBJS += sha1dc/sha1.o
LIB_OBJS += sha1dc/ubc_check.o
BASIC_CFLAGS += -DSHA1_DC
BASIC_CFLAGS += \
-DSHA1_DC \
-DSHA1DC_NO_STANDARD_INCLUDES \
-DSHA1DC_INIT_SAFE_HASH_DEFAULT=0 \
-DSHA1DC_CUSTOM_INCLUDE_SHA1_C="\"cache.h\"" \
-DSHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_C="\"sha1dc_git.c\"" \
-DSHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H="\"sha1dc_git.h\"" \
-DSHA1DC_CUSTOM_INCLUDE_UBC_CHECK_C="\"git-compat-util.h\""
endif
endif
endif

93
sha1dc/sha1.c
View File

@ -5,9 +5,23 @@
* https://opensource.org/licenses/MIT
***/
#include "cache.h"
#include "sha1dc/sha1.h"
#include "sha1dc/ubc_check.h"
#ifndef SHA1DC_NO_STANDARD_INCLUDES
#include <string.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#endif
#ifdef SHA1DC_CUSTOM_INCLUDE_SHA1_C
#include SHA1DC_CUSTOM_INCLUDE_SHA1_C
#endif
#ifndef SHA1DC_INIT_SAFE_HASH_DEFAULT
#define SHA1DC_INIT_SAFE_HASH_DEFAULT 1
#endif
#include "sha1.h"
#include "ubc_check.h"
/*
@ -18,16 +32,31 @@
If you are compiling on a big endian platform and your compiler does not define one of these,
you will have to add whatever macros your tool chain defines to indicate Big-Endianness.
*/
#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || \
(defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __BIG_ENDIAN__)) || \
defined(__BIG_ENDIAN__) || defined(__ARMEB__) || defined(__THUMBEB__) || defined(__AARCH64EB__) || \
defined(_MIPSEB) || defined(__MIPSEB) || defined(__MIPSEB__)
#define SHA1DC_BIGENDIAN 1
#else
#ifdef SHA1DC_BIGENDIAN
#undef SHA1DC_BIGENDIAN
#endif
#if (!defined SHA1DC_FORCE_LITTLEENDIAN) && \
((defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || \
(defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __BIG_ENDIAN__)) || \
defined(_BIG_ENDIAN) || defined(__BIG_ENDIAN__) || defined(__ARMEB__) || defined(__THUMBEB__) || defined(__AARCH64EB__) || \
defined(_MIPSEB) || defined(__MIPSEB) || defined(__MIPSEB__) || defined(SHA1DC_FORCE_BIGENDIAN))
#define SHA1DC_BIGENDIAN
#endif /*ENDIANNESS SELECTION*/
#if (defined SHA1DC_FORCE_UNALIGNED_ACCESS || \
defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || \
defined(i386) || defined(__i386) || defined(__i386__) || defined(__i486__) || \
defined(__i586__) || defined(__i686__) || defined(_M_IX86) || defined(__X86__) || \
defined(_X86_) || defined(__THW_INTEL__) || defined(__I86__) || defined(__INTEL__) || \
defined(__386) || defined(_M_X64) || defined(_M_AMD64))
#define SHA1DC_ALLOW_UNALIGNED_ACCESS
#endif /*UNALIGNMENT DETECTION*/
#define rotate_right(x,n) (((x)>>(n))|((x)<<(32-(n))))
#define rotate_left(x,n) (((x)<<(n))|((x)>>(32-(n))))
@ -36,11 +65,11 @@
#define sha1_mix(W, t) (rotate_left(W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16], 1))
#if defined(SHA1DC_BIGENDIAN)
#ifdef SHA1DC_BIGENDIAN
#define sha1_load(m, t, temp) { temp = m[t]; }
#else
#define sha1_load(m, t, temp) { temp = m[t]; sha1_bswap32(temp); }
#endif /* !defined(SHA1DC_BIGENDIAN) */
#endif
#define sha1_store(W, t, x) *(volatile uint32_t *)&W[t] = x
@ -869,6 +898,11 @@ static void sha1recompress_fast_ ## t (uint32_t ihvin[5], uint32_t ihvout[5], co
ihvout[0] = ihvin[0] + a; ihvout[1] = ihvin[1] + b; ihvout[2] = ihvin[2] + c; ihvout[3] = ihvin[3] + d; ihvout[4] = ihvin[4] + e; \
}
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4127) /* Complier complains about the checks in the above macro being constant. */
#endif
#ifdef DOSTORESTATE0
SHA1_RECOMPRESS(0)
#endif
@ -1189,6 +1223,10 @@ SHA1_RECOMPRESS(78)
SHA1_RECOMPRESS(79)
#endif
#ifdef _MSC_VER
#pragma warning(pop)
#endif
static void sha1_recompression_step(uint32_t step, uint32_t ihvin[5], uint32_t ihvout[5], const uint32_t me2[80], const uint32_t state[5])
{
switch (step)
@ -1662,7 +1700,7 @@ void SHA1DCInit(SHA1_CTX* ctx)
ctx->ihv[3] = 0x10325476;
ctx->ihv[4] = 0xC3D2E1F0;
ctx->found_collision = 0;
ctx->safe_hash = 0;
ctx->safe_hash = SHA1DC_INIT_SAFE_HASH_DEFAULT;
ctx->ubc_check = 1;
ctx->detect_coll = 1;
ctx->reduced_round_coll = 0;
@ -1710,6 +1748,7 @@ void SHA1DCSetCallback(SHA1_CTX* ctx, collision_block_callback callback)
void SHA1DCUpdate(SHA1_CTX* ctx, const char* buf, size_t len)
{
unsigned left, fill;
if (len == 0)
return;
@ -1728,7 +1767,13 @@ void SHA1DCUpdate(SHA1_CTX* ctx, const char* buf, size_t len)
while (len >= 64)
{
ctx->total += 64;
#if defined(SHA1DC_ALLOW_UNALIGNED_ACCESS)
sha1_process(ctx, (uint32_t*)(buf));
#else
memcpy(ctx->buffer, buf, 64);
sha1_process(ctx, (uint32_t*)(ctx->buffer));
#endif /* defined(SHA1DC_ALLOW_UNALIGNED_ACCESS) */
buf += 64;
len -= 64;
}
@ -1788,22 +1833,6 @@ int SHA1DCFinal(unsigned char output[20], SHA1_CTX *ctx)
return ctx->found_collision;
}
void git_SHA1DCFinal(unsigned char hash[20], SHA1_CTX *ctx)
{
if (!SHA1DCFinal(hash, ctx))
return;
die("SHA-1 appears to be part of a collision attack: %s",
sha1_to_hex(hash));
}
void git_SHA1DCUpdate(SHA1_CTX *ctx, const void *vdata, unsigned long len)
{
const char *data = vdata;
/* We expect an unsigned long, but sha1dc only takes an int */
while (len > INT_MAX) {
SHA1DCUpdate(ctx, data, INT_MAX);
data += INT_MAX;
len -= INT_MAX;
}
SHA1DCUpdate(ctx, data, len);
}
#ifdef SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_C
#include SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_C
#endif

90
sha1dc/sha1.h
View File

@ -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 @@
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]); */
#ifndef SHA1DC_NO_STANDARD_INCLUDES
#include <stdint.h>
#endif
/* 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]); */
/* 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 {
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);
/* 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

13
sha1dc/ubc_check.c
View File

@ -24,8 +24,13 @@
// ubc_check has been verified against ubc_check_verify using the 'ubc_check_test' program in the tools section
*/
#include "git-compat-util.h"
#include "sha1dc/ubc_check.h"
#ifndef SHA1DC_NO_STANDARD_INCLUDES
#include <stdint.h>
#endif
#ifdef SHA1DC_CUSTOM_INCLUDE_UBC_CHECK_C
#include SHA1DC_CUSTOM_INCLUDE_UBC_CHECK_C
#endif
#include "ubc_check.h"
static const uint32_t DV_I_43_0_bit = (uint32_t)(1) << 0;
static const uint32_t DV_I_44_0_bit = (uint32_t)(1) << 1;
@ -361,3 +366,7 @@ if (mask) {
dvmask[0]=mask;
}
#ifdef SHA1DC_CUSTOM_TRAILING_INCLUDE_UBC_CHECK_C
#include SHA1DC_CUSTOM_TRAILING_INCLUDE_UBC_CHECK_C
#endif

14
sha1dc/ubc_check.h
View File

@ -20,13 +20,17 @@
// thus one needs to do the recompression check for each DV that has its bit set
*/
#ifndef UBC_CHECK_H
#define UBC_CHECK_H
#ifndef SHA1DC_UBC_CHECK_H
#define SHA1DC_UBC_CHECK_H
#if defined(__cplusplus)
extern "C" {
#endif
#ifndef SHA1DC_NO_STANDARD_INCLUDES
#include <stdint.h>
#endif
#define DVMASKSIZE 1
typedef struct { int dvType; int dvK; int dvB; int testt; int maski; int maskb; uint32_t dm[80]; } dv_info_t;
extern dv_info_t sha1_dvs[];
@ -41,4 +45,8 @@ void ubc_check(const uint32_t W[80], uint32_t dvmask[DVMASKSIZE]);
}
#endif
#endif /* UBC_CHECK_H */
#ifdef SHA1DC_CUSTOM_TRAILING_INCLUDE_UBC_CHECK_H
#include SHA1DC_CUSTOM_TRAILING_INCLUDE_UBC_CHECK_H
#endif
#endif

24
sha1dc_git.c Normal file
View File

@ -0,0 +1,24 @@
/*
* This code is included at the end of sha1dc/sha1.c with the
* SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_C macro.
*/
void git_SHA1DCFinal(unsigned char hash[20], SHA1_CTX *ctx)
{
if (!SHA1DCFinal(hash, ctx))
return;
die("SHA-1 appears to be part of a collision attack: %s",
sha1_to_hex(hash));
}
void git_SHA1DCUpdate(SHA1_CTX *ctx, const void *vdata, unsigned long len)
{
const char *data = vdata;
/* We expect an unsigned long, but sha1dc only takes an int */
while (len > INT_MAX) {
SHA1DCUpdate(ctx, data, INT_MAX);
data += INT_MAX;
len -= INT_MAX;
}
SHA1DCUpdate(ctx, data, len);
}

19
sha1dc_git.h Normal file
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@ -0,0 +1,19 @@
/*
* This code is included at the end of sha1dc/sha1.h with the
* SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_H macro.
*/
/*
* 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