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/*
* SHA1 hash algorithm. Used in SSH-2 as a MAC, and the transform is
* also used as a `stirring' function for the PuTTY random number
* pool. Implemented directly from the specification by Simon
* Tatham.
*/
#include "ssh.h"
/* ----------------------------------------------------------------------
* Core SHA algorithm: processes 16-word blocks into a message digest.
*/
#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
static void SHA_Core_Init(uint32 h[5])
{
h[0] = 0x67452301;
h[1] = 0xefcdab89;
h[2] = 0x98badcfe;
h[3] = 0x10325476;
h[4] = 0xc3d2e1f0;
}
void SHATransform(word32 * digest, word32 * block)
{
word32 w[80];
word32 a, b, c, d, e;
int t;
for (t = 0; t < 16; t++)
w[t] = block[t];
for (t = 16; t < 80; t++) {
word32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
w[t] = rol(tmp, 1);
}
a = digest[0];
b = digest[1];
c = digest[2];
d = digest[3];
e = digest[4];
for (t = 0; t < 20; t++) {
word32 tmp =
rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
e = d;
d = c;
c = rol(b, 30);
b = a;
a = tmp;
}
for (t = 20; t < 40; t++) {
word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
e = d;
d = c;
c = rol(b, 30);
b = a;
a = tmp;
}
for (t = 40; t < 60; t++) {
word32 tmp = rol(a,
5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
0x8f1bbcdc;
e = d;
d = c;
c = rol(b, 30);
b = a;
a = tmp;
}
for (t = 60; t < 80; t++) {
word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
e = d;
d = c;
c = rol(b, 30);
b = a;
a = tmp;
}
digest[0] += a;
digest[1] += b;
digest[2] += c;
digest[3] += d;
digest[4] += e;
}
/* ----------------------------------------------------------------------
* Outer SHA 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 SHA algorithm.
*/
void SHA_Init(SHA_State * s)
{
SHA_Core_Init(s->h);
s->blkused = 0;
s->lenhi = s->lenlo = 0;
}
void SHA_Bytes(SHA_State * s, 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 < 64) {
/*
* 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 >= 64) {
memcpy(s->block + s->blkused, q, 64 - s->blkused);
q += 64 - s->blkused;
len -= 64 - 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);
}
SHATransform(s->h, wordblock);
s->blkused = 0;
}
memcpy(s->block, q, len);
s->blkused = len;
}
}
void SHA_Final(SHA_State * s, unsigned char *output)
{
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;
SHA_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;
SHA_Bytes(s, &c, 8);
for (i = 0; i < 5; i++) {
output[i * 4] = (s->h[i] >> 24) & 0xFF;
output[i * 4 + 1] = (s->h[i] >> 16) & 0xFF;
output[i * 4 + 2] = (s->h[i] >> 8) & 0xFF;
output[i * 4 + 3] = (s->h[i]) & 0xFF;
}
}
void SHA_Simple(void *p, int len, unsigned char *output)
{
SHA_State s;
SHA_Init(&s);
SHA_Bytes(&s, p, len);
SHA_Final(&s, output);
}
/*
* Thin abstraction for things where hashes are pluggable.
*/
static void *sha1_init(void)
{
SHA_State *s;
s = snew(SHA_State);
SHA_Init(s);
return s;
}
static void sha1_bytes(void *handle, void *p, int len)
{
SHA_State *s = handle;
SHA_Bytes(s, p, len);
}
static void sha1_final(void *handle, unsigned char *output)
{
SHA_State *s = handle;
SHA_Final(s, output);
sfree(s);
}
const struct ssh_hash ssh_sha1 = {
sha1_init, sha1_bytes, sha1_final, 20, "SHA-1"
};
/* ----------------------------------------------------------------------
* The above is the SHA-1 algorithm itself. Now we implement the
* HMAC wrapper on it.
*/
static void *sha1_make_context(void)
{
return snewn(3, SHA_State);
}
static void sha1_free_context(void *handle)
{
sfree(handle);
}
static void sha1_key_internal(void *handle, unsigned char *key, int len)
{
SHA_State *keys = (SHA_State *)handle;
unsigned char foo[64];
int i;
memset(foo, 0x36, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA_Init(&keys[0]);
SHA_Bytes(&keys[0], foo, 64);
memset(foo, 0x5C, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA_Init(&keys[1]);
SHA_Bytes(&keys[1], foo, 64);
memset(foo, 0, 64); /* burn the evidence */
}
static void sha1_key(void *handle, unsigned char *key)
{
sha1_key_internal(handle, key, 20);
}
static void sha1_key_buggy(void *handle, unsigned char *key)
{
sha1_key_internal(handle, key, 16);
}
static void hmacsha1_start(void *handle)
{
SHA_State *keys = (SHA_State *)handle;
keys[2] = keys[0]; /* structure copy */
}
static void hmacsha1_bytes(void *handle, unsigned char const *blk, int len)
{
SHA_State *keys = (SHA_State *)handle;
SHA_Bytes(&keys[2], (void *)blk, len);
}
static void hmacsha1_genresult(void *handle, unsigned char *hmac)
{
SHA_State *keys = (SHA_State *)handle;
SHA_State s;
unsigned char intermediate[20];
s = keys[2]; /* structure copy */
SHA_Final(&s, intermediate);
s = keys[1]; /* structure copy */
SHA_Bytes(&s, intermediate, 20);
SHA_Final(&s, hmac);
}
static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
unsigned long seq, unsigned char *hmac)
{
unsigned char seqbuf[4];
seqbuf[0] = (unsigned char) ((seq >> 24) & 0xFF);
seqbuf[1] = (unsigned char) ((seq >> 16) & 0xFF);
seqbuf[2] = (unsigned char) ((seq >> 8) & 0xFF);
seqbuf[3] = (unsigned char) ((seq) & 0xFF);
hmacsha1_start(handle);
hmacsha1_bytes(handle, seqbuf, 4);
hmacsha1_bytes(handle, blk, len);
hmacsha1_genresult(handle, hmac);
}
static void sha1_generate(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
sha1_do_hmac(handle, blk, len, seq, blk + len);
}
static int hmacsha1_verresult(void *handle, unsigned char const *hmac)
{
unsigned char correct[20];
hmacsha1_genresult(handle, correct);
return !memcmp(correct, hmac, 20);
}
static int sha1_verify(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
unsigned char correct[20];
sha1_do_hmac(handle, blk, len, seq, correct);
return !memcmp(correct, blk + len, 20);
}
static void hmacsha1_96_genresult(void *handle, unsigned char *hmac)
{
unsigned char full[20];
hmacsha1_genresult(handle, full);
memcpy(hmac, full, 12);
}
static void sha1_96_generate(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
unsigned char full[20];
sha1_do_hmac(handle, blk, len, seq, full);
memcpy(blk + len, full, 12);
}
static int hmacsha1_96_verresult(void *handle, unsigned char const *hmac)
{
unsigned char correct[20];
hmacsha1_genresult(handle, correct);
return !memcmp(correct, hmac, 12);
}
static int sha1_96_verify(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
unsigned char correct[20];
sha1_do_hmac(handle, blk, len, seq, correct);
return !memcmp(correct, blk + len, 12);
}
void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
unsigned char *output) {
SHA_State states[2];
unsigned char intermediate[20];
sha1_key_internal(states, key, keylen);
SHA_Bytes(&states[0], data, datalen);
SHA_Final(&states[0], intermediate);
SHA_Bytes(&states[1], intermediate, 20);
SHA_Final(&states[1], output);
}
const struct ssh_mac ssh_hmac_sha1 = {
sha1_make_context, sha1_free_context, sha1_key,
sha1_generate, sha1_verify,
hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
"hmac-sha1",
20,
"HMAC-SHA1"
};
const struct ssh_mac ssh_hmac_sha1_96 = {
sha1_make_context, sha1_free_context, sha1_key,
sha1_96_generate, sha1_96_verify,
hmacsha1_start, hmacsha1_bytes,
hmacsha1_96_genresult, hmacsha1_96_verresult,
"hmac-sha1-96",
12,
"HMAC-SHA1-96"
};
const struct ssh_mac ssh_hmac_sha1_buggy = {
sha1_make_context, sha1_free_context, sha1_key_buggy,
sha1_generate, sha1_verify,
hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
"hmac-sha1",
20,
"bug-compatible HMAC-SHA1"
};
const struct ssh_mac ssh_hmac_sha1_96_buggy = {
sha1_make_context, sha1_free_context, sha1_key_buggy,
sha1_96_generate, sha1_96_verify,
hmacsha1_start, hmacsha1_bytes,
hmacsha1_96_genresult, hmacsha1_96_verresult,
"hmac-sha1-96",
12,
"bug-compatible HMAC-SHA1-96"
};
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