gosthash.c
/**********************************************************************
* gosthash.c *
* Copyright (c) 2005-2006 Cryptocom LTD *
* This file is distributed under the same license as OpenSSL *
* *
* Implementation of GOST R 34.11-94 hash function *
* uses on gost89.c and gost89.h Doesn't need OpenSSL *
**********************************************************************/
#include <string.h>
#include "gost89.h"
#include "gosthash.h"
/*
* Use OPENSSL_malloc for memory allocation if compiled with
* -DOPENSSL_BUILD, and libc malloc otherwise
*/
#ifndef MYALLOC
# ifdef OPENSSL_BUILD
# include <openssl/crypto.h>
# define MYALLOC(size) OPENSSL_malloc(size)
# define MYFREE(ptr) OPENSSL_free(ptr)
# else
# define MYALLOC(size) malloc(size)
# define MYFREE(ptr) free(ptr)
# endif
#endif
/*
* Following functions are various bit meshing routines used in GOST R
* 34.11-94 algorithms
*/
static void swap_bytes(byte * w, byte * k)
{
int i, j;
for (i = 0; i < 4; i++)
for (j = 0; j < 8; j++)
k[i + 4 * j] = w[8 * i + j];
}
/* was A_A */
static void circle_xor8(const byte * w, byte * k)
{
byte buf[8];
int i;
memcpy(buf, w, 8);
memmove(k, w + 8, 24);
for (i = 0; i < 8; i++)
k[i + 24] = buf[i] ^ k[i];
}
/* was R_R */
static void transform_3(byte * data)
{
unsigned short int acc;
acc = (data[0] ^ data[2] ^ data[4] ^ data[6] ^ data[24] ^ data[30]) |
((data[1] ^ data[3] ^ data[5] ^ data[7] ^ data[25] ^ data[31]) << 8);
memmove(data, data + 2, 30);
data[30] = acc & 0xff;
data[31] = acc >> 8;
}
/* Adds blocks of N bytes modulo 2**(8*n). Returns carry*/
static int add_blocks(int n, byte * left, const byte * right)
{
int i;
int carry = 0;
int sum;
for (i = 0; i < n; i++) {
sum = (int)left[i] + (int)right[i] + carry;
left[i] = sum & 0xff;
carry = sum >> 8;
}
return carry;
}
/* Xor two sequences of bytes */
static void xor_blocks(byte * result, const byte * a, const byte * b,
size_t len)
{
size_t i;
for (i = 0; i < len; i++)
result[i] = a[i] ^ b[i];
}
/*
* Calculate H(i+1) = Hash(Hi,Mi)
* Where H and M are 32 bytes long
*/
static int hash_step(gost_ctx * c, byte * H, const byte * M)
{
byte U[32], W[32], V[32], S[32], Key[32];
int i;
/* Compute first key */
xor_blocks(W, H, M, 32);
swap_bytes(W, Key);
/* Encrypt first 8 bytes of H with first key */
gost_enc_with_key(c, Key, H, S);
/* Compute second key */
circle_xor8(H, U);
circle_xor8(M, V);
circle_xor8(V, V);
xor_blocks(W, U, V, 32);
swap_bytes(W, Key);
/* encrypt second 8 bytes of H with second key */
gost_enc_with_key(c, Key, H + 8, S + 8);
/* compute third key */
circle_xor8(U, U);
U[31] = ~U[31];
U[29] = ~U[29];
U[28] = ~U[28];
U[24] = ~U[24];
U[23] = ~U[23];
U[20] = ~U[20];
U[18] = ~U[18];
U[17] = ~U[17];
U[14] = ~U[14];
U[12] = ~U[12];
U[10] = ~U[10];
U[8] = ~U[8];
U[7] = ~U[7];
U[5] = ~U[5];
U[3] = ~U[3];
U[1] = ~U[1];
circle_xor8(V, V);
circle_xor8(V, V);
xor_blocks(W, U, V, 32);
swap_bytes(W, Key);
/* encrypt third 8 bytes of H with third key */
gost_enc_with_key(c, Key, H + 16, S + 16);
/* Compute fourth key */
circle_xor8(U, U);
circle_xor8(V, V);
circle_xor8(V, V);
xor_blocks(W, U, V, 32);
swap_bytes(W, Key);
/* Encrypt last 8 bytes with fourth key */
gost_enc_with_key(c, Key, H + 24, S + 24);
for (i = 0; i < 12; i++)
transform_3(S);
xor_blocks(S, S, M, 32);
transform_3(S);
xor_blocks(S, S, H, 32);
for (i = 0; i < 61; i++)
transform_3(S);
memcpy(H, S, 32);
return 1;
}
/*
* Initialize gost_hash ctx - cleans up temporary structures and set up
* substitution blocks
*/
int init_gost_hash_ctx(gost_hash_ctx * ctx,
const gost_subst_block * subst_block)
{
memset(ctx, 0, sizeof(gost_hash_ctx));
ctx->cipher_ctx = (gost_ctx *) MYALLOC(sizeof(gost_ctx));
if (!ctx->cipher_ctx) {
return 0;
}
gost_init(ctx->cipher_ctx, subst_block);
return 1;
}
/*
* Free cipher CTX if it is dynamically allocated. Do not use
* if cipher ctx is statically allocated as in OpenSSL implementation of
* GOST hash algroritm
*
*/
void done_gost_hash_ctx(gost_hash_ctx * ctx)
{
/*
* No need to use gost_destroy, because cipher keys are not really secret
* when hashing
*/
MYFREE(ctx->cipher_ctx);
}
/*
* reset state of hash context to begin hashing new message
*/
int start_hash(gost_hash_ctx * ctx)
{
if (!ctx->cipher_ctx)
return 0;
memset(&(ctx->H), 0, 32);
memset(&(ctx->S), 0, 32);
ctx->len = 0L;
ctx->left = 0;
return 1;
}
/*
* Hash block of arbitrary length
*
*
*/
int hash_block(gost_hash_ctx * ctx, const byte * block, size_t length)
{
if (ctx->left) {
/*
* There are some bytes from previous step
*/
unsigned int add_bytes = 32 - ctx->left;
if (add_bytes > length) {
add_bytes = length;
}
memcpy(&(ctx->remainder[ctx->left]), block, add_bytes);
ctx->left += add_bytes;
if (ctx->left < 32) {
return 1;
}
block += add_bytes;
length -= add_bytes;
hash_step(ctx->cipher_ctx, ctx->H, ctx->remainder);
add_blocks(32, ctx->S, ctx->remainder);
ctx->len += 32;
ctx->left = 0;
}
while (length >= 32) {
hash_step(ctx->cipher_ctx, ctx->H, block);
add_blocks(32, ctx->S, block);
ctx->len += 32;
block += 32;
length -= 32;
}
if (length) {
memcpy(ctx->remainder, block, ctx->left = length);
}
return 1;
}
/*
* Compute hash value from current state of ctx
* state of hash ctx becomes invalid and cannot be used for further
* hashing.
*/
int finish_hash(gost_hash_ctx * ctx, byte * hashval)
{
byte buf[32];
byte H[32];
byte S[32];
ghosthash_len fin_len = ctx->len;
byte *bptr;
memcpy(H, ctx->H, 32);
memcpy(S, ctx->S, 32);
if (ctx->left) {
memset(buf, 0, 32);
memcpy(buf, ctx->remainder, ctx->left);
hash_step(ctx->cipher_ctx, H, buf);
add_blocks(32, S, buf);
fin_len += ctx->left;
}
memset(buf, 0, 32);
bptr = buf;
fin_len <<= 3; /* Hash length in BITS!! */
while (fin_len > 0) {
*(bptr++) = (byte) (fin_len & 0xFF);
fin_len >>= 8;
};
hash_step(ctx->cipher_ctx, H, buf);
hash_step(ctx->cipher_ctx, H, S);
memcpy(hashval, H, 32);
return 1;
}
