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/*
* SHA-256 algorithm as described at
*
* http://csrc.nist.gov/cryptval/shs.html
*/
#include "ssh.h"
/* ----------------------------------------------------------------------
* Core SHA256 algorithm: processes 16-word blocks into a message digest.
*/
#define ror(x,y) ( ((x) << (32-y)) | (((uint32)(x)) >> (y)) )
#define shr(x,y) ( (((uint32)(x)) >> (y)) )
#define Ch(x,y,z) ( ((x) & (y)) ^ (~(x) & (z)) )
#define Maj(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) )
#define bigsigma0(x) ( ror((x),2) ^ ror((x),13) ^ ror((x),22) )
#define bigsigma1(x) ( ror((x),6) ^ ror((x),11) ^ ror((x),25) )
#define smallsigma0(x) ( ror((x),7) ^ ror((x),18) ^ shr((x),3) )
#define smallsigma1(x) ( ror((x),17) ^ ror((x),19) ^ shr((x),10) )
void SHA256_Core_Init(SHA256_State *s) {
s->h[0] = 0x6a09e667;
s->h[1] = 0xbb67ae85;
s->h[2] = 0x3c6ef372;
s->h[3] = 0xa54ff53a;
s->h[4] = 0x510e527f;
s->h[5] = 0x9b05688c;
s->h[6] = 0x1f83d9ab;
s->h[7] = 0x5be0cd19;
}
void SHA256_Block(SHA256_State *s, uint32 *block) {
uint32 w[80];
uint32 a,b,c,d,e,f,g,h;
static const int k[] = {
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
};
int t;
for (t = 0; t < 16; t++)
w[t] = block[t];
for (t = 16; t < 64; t++)
w[t] = smallsigma1(w[t-2]) + w[t-7] + smallsigma0(w[t-15]) + w[t-16];
a = s->h[0]; b = s->h[1]; c = s->h[2]; d = s->h[3];
e = s->h[4]; f = s->h[5]; g = s->h[6]; h = s->h[7];
for (t = 0; t < 64; t+=8) {
uint32 t1, t2;
#define ROUND(j,a,b,c,d,e,f,g,h) \
t1 = h + bigsigma1(e) + Ch(e,f,g) + k[j] + w[j]; \
t2 = bigsigma0(a) + Maj(a,b,c); \
d = d + t1; h = t1 + t2;
ROUND(t+0, a,b,c,d,e,f,g,h);
ROUND(t+1, h,a,b,c,d,e,f,g);
ROUND(t+2, g,h,a,b,c,d,e,f);
ROUND(t+3, f,g,h,a,b,c,d,e);
ROUND(t+4, e,f,g,h,a,b,c,d);
ROUND(t+5, d,e,f,g,h,a,b,c);
ROUND(t+6, c,d,e,f,g,h,a,b);
ROUND(t+7, b,c,d,e,f,g,h,a);
}
s->h[0] += a; s->h[1] += b; s->h[2] += c; s->h[3] += d;
s->h[4] += e; s->h[5] += f; s->h[6] += g; s->h[7] += h;
}
/* ----------------------------------------------------------------------
* Outer SHA256 algorithm: take an arbitrary length byte string,
* convert it into 16-word blocks with the prescribed padding at
* the end, and pass those blocks to the core SHA256 algorithm.
*/
#define BLKSIZE 64
void SHA256_Init(SHA256_State *s) {
SHA256_Core_Init(s);
s->blkused = 0;
s->lenhi = s->lenlo = 0;
}
void SHA256_Bytes(SHA256_State *s, const void *p, int len) {
unsigned char *q = (unsigned char *)p;
uint32 wordblock[16];
uint32 lenw = len;
int i;
/*
* Update the length field.
*/
s->lenlo += lenw;
s->lenhi += (s->lenlo < lenw);
if (s->blkused && s->blkused+len < BLKSIZE) {
/*
* Trivial case: just add to the block.
*/
memcpy(s->block + s->blkused, q, len);
s->blkused += len;
} else {
/*
* We must complete and process at least one block.
*/
while (s->blkused + len >= BLKSIZE) {
memcpy(s->block + s->blkused, q, BLKSIZE - s->blkused);
q += BLKSIZE - s->blkused;
len -= BLKSIZE - s->blkused;
/* Now process the block. Gather bytes big-endian into words */
for (i = 0; i < 16; i++) {
wordblock[i] =
( ((uint32)s->block[i*4+0]) << 24 ) |
( ((uint32)s->block[i*4+1]) << 16 ) |
( ((uint32)s->block[i*4+2]) << 8 ) |
( ((uint32)s->block[i*4+3]) << 0 );
}
SHA256_Block(s, wordblock);
s->blkused = 0;
}
memcpy(s->block, q, len);
s->blkused = len;
}
}
void SHA256_Final(SHA256_State *s, unsigned char *digest) {
int i;
int pad;
unsigned char c[64];
uint32 lenhi, lenlo;
if (s->blkused >= 56)
pad = 56 + 64 - s->blkused;
else
pad = 56 - s->blkused;
lenhi = (s->lenhi << 3) | (s->lenlo >> (32-3));
lenlo = (s->lenlo << 3);
memset(c, 0, pad);
c[0] = 0x80;
SHA256_Bytes(s, &c, pad);
c[0] = (lenhi >> 24) & 0xFF;
c[1] = (lenhi >> 16) & 0xFF;
c[2] = (lenhi >> 8) & 0xFF;
c[3] = (lenhi >> 0) & 0xFF;
c[4] = (lenlo >> 24) & 0xFF;
c[5] = (lenlo >> 16) & 0xFF;
c[6] = (lenlo >> 8) & 0xFF;
c[7] = (lenlo >> 0) & 0xFF;
SHA256_Bytes(s, &c, 8);
for (i = 0; i < 8; i++) {
digest[i*4+0] = (s->h[i] >> 24) & 0xFF;
digest[i*4+1] = (s->h[i] >> 16) & 0xFF;
digest[i*4+2] = (s->h[i] >> 8) & 0xFF;
digest[i*4+3] = (s->h[i] >> 0) & 0xFF;
}
}
void SHA256_Simple(const void *p, int len, unsigned char *output) {
SHA256_State s;
SHA256_Init(&s);
SHA256_Bytes(&s, p, len);
SHA256_Final(&s, output);
}
/*
* Thin abstraction for things where hashes are pluggable.
*/
static void *sha256_init(void)
{
SHA256_State *s;
s = snew(SHA256_State);
SHA256_Init(s);
return s;
}
static void sha256_bytes(void *handle, void *p, int len)
{
SHA256_State *s = handle;
SHA256_Bytes(s, p, len);
}
static void sha256_final(void *handle, unsigned char *output)
{
SHA256_State *s = handle;
SHA256_Final(s, output);
sfree(s);
}
const struct ssh_hash ssh_sha256 = {
sha256_init, sha256_bytes, sha256_final, 32, "SHA-256"
};
/* ----------------------------------------------------------------------
* The above is the SHA-256 algorithm itself. Now we implement the
* HMAC wrapper on it.
*/
static void *sha256_make_context(void)
{
return snewn(3, SHA256_State);
}
static void sha256_free_context(void *handle)
{
sfree(handle);
}
static void sha256_key_internal(void *handle, unsigned char *key, int len)
{
SHA256_State *keys = (SHA256_State *)handle;
unsigned char foo[64];
int i;
memset(foo, 0x36, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA256_Init(&keys[0]);
SHA256_Bytes(&keys[0], foo, 64);
memset(foo, 0x5C, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA256_Init(&keys[1]);
SHA256_Bytes(&keys[1], foo, 64);
smemclr(foo, 64); /* burn the evidence */
}
static void sha256_key(void *handle, unsigned char *key)
{
sha256_key_internal(handle, key, 32);
}
static void hmacsha256_start(void *handle)
{
SHA256_State *keys = (SHA256_State *)handle;
keys[2] = keys[0]; /* structure copy */
}
static void hmacsha256_bytes(void *handle, unsigned char const *blk, int len)
{
SHA256_State *keys = (SHA256_State *)handle;
SHA256_Bytes(&keys[2], (void *)blk, len);
}
static void hmacsha256_genresult(void *handle, unsigned char *hmac)
{
SHA256_State *keys = (SHA256_State *)handle;
SHA256_State s;
unsigned char intermediate[32];
s = keys[2]; /* structure copy */
SHA256_Final(&s, intermediate);
s = keys[1]; /* structure copy */
SHA256_Bytes(&s, intermediate, 32);
SHA256_Final(&s, hmac);
}
static void sha256_do_hmac(void *handle, unsigned char *blk, int len,
unsigned long seq, unsigned char *hmac)
{
unsigned char seqbuf[4];
PUT_32BIT_MSB_FIRST(seqbuf, seq);
hmacsha256_start(handle);
hmacsha256_bytes(handle, seqbuf, 4);
hmacsha256_bytes(handle, blk, len);
hmacsha256_genresult(handle, hmac);
}
static void sha256_generate(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
sha256_do_hmac(handle, blk, len, seq, blk + len);
}
static int hmacsha256_verresult(void *handle, unsigned char const *hmac)
{
unsigned char correct[32];
hmacsha256_genresult(handle, correct);
return !memcmp(correct, hmac, 32);
}
static int sha256_verify(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
unsigned char correct[32];
sha256_do_hmac(handle, blk, len, seq, correct);
return !memcmp(correct, blk + len, 32);
}
const struct ssh_mac ssh_hmac_sha256 = {
sha256_make_context, sha256_free_context, sha256_key,
sha256_generate, sha256_verify,
hmacsha256_start, hmacsha256_bytes,
hmacsha256_genresult, hmacsha256_verresult,
"hmac-sha2-256",
32,
"HMAC-SHA-256"
};
#ifdef TEST
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
int main(void) {
unsigned char digest[32];
int i, j, errors;
struct {
const char *teststring;
unsigned char digest[32];
} tests[] = {
{ "abc", {
0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad,
} },
{ "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", {
0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1,
} },
};
errors = 0;
for (i = 0; i < sizeof(tests) / sizeof(*tests); i++) {
SHA256_Simple(tests[i].teststring,
strlen(tests[i].teststring), digest);
for (j = 0; j < 32; j++) {
if (digest[j] != tests[i].digest[j]) {
fprintf(stderr,
"\"%s\" digest byte %d should be 0x%02x, is 0x%02x\n",
tests[i].teststring, j, tests[i].digest[j], digest[j]);
errors++;
}
}
}
printf("%d errors\n", errors);
return 0;
}
#endif
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