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Second attempt. Can successfully decrypt the _first block_ of a packet.

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[originally from svn r570]
This commit is contained in:
Simon Tatham
2000-09-05 16:23:36 +00:00
parent 35205e5cb7
commit 36a499a7f1
5 changed files with 169 additions and 37 deletions
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35
sshsha.c
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@ -170,28 +170,39 @@ void SHA_Simple(void *p, int len, unsigned char *output) {
* HMAC wrapper on it.
*/
static SHA_State sha1_mac_s1, sha1_mac_s2;
static SHA_State sha1_cs_mac_s1, sha1_cs_mac_s2;
static SHA_State sha1_sc_mac_s1, sha1_sc_mac_s2;
static void sha1_sesskey(unsigned char *key, int len) {
static void sha1_key(SHA_State *s1, SHA_State *s2,
unsigned char *key, int len) {
unsigned char foo[64];
int i;
memset(foo, 0x36, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA_Init(&sha1_mac_s1);
SHA_Bytes(&sha1_mac_s1, foo, 64);
SHA_Init(s1);
SHA_Bytes(s1, foo, 64);
memset(foo, 0x5C, 64);
for (i = 0; i < len && i < 64; i++)
foo[i] ^= key[i];
SHA_Init(&sha1_mac_s2);
SHA_Bytes(&sha1_mac_s2, foo, 64);
SHA_Init(s2);
SHA_Bytes(s2, foo, 64);
memset(foo, 0, 64); /* burn the evidence */
}
static void sha1_do_hmac(unsigned char *blk, int len, unsigned long seq,
static void sha1_cskey(unsigned char *key) {
sha1_key(&sha1_cs_mac_s1, &sha1_cs_mac_s2, key, 20);
}
static void sha1_sckey(unsigned char *key) {
sha1_key(&sha1_sc_mac_s1, &sha1_sc_mac_s2, key, 20);
}
static void sha1_do_hmac(SHA_State *s1, SHA_State *s2,
unsigned char *blk, int len, unsigned long seq,
unsigned char *hmac) {
SHA_State s;
unsigned char intermediate[20];
@ -201,27 +212,27 @@ static void sha1_do_hmac(unsigned char *blk, int len, unsigned long seq,
intermediate[2] = (unsigned char)((seq >> 8) & 0xFF);
intermediate[3] = (unsigned char)((seq ) & 0xFF);
s = sha1_mac_s1; /* structure copy */
s = *s1; /* structure copy */
SHA_Bytes(&s, intermediate, 4);
SHA_Bytes(&s, blk, len);
SHA_Final(&s, intermediate);
s = sha1_mac_s2; /* structure copy */
s = *s2; /* structure copy */
SHA_Bytes(&s, intermediate, 20);
SHA_Final(&s, hmac);
}
static void sha1_generate(unsigned char *blk, int len, unsigned long seq) {
sha1_do_hmac(blk, len, seq, blk+len);
sha1_do_hmac(&sha1_cs_mac_s1, &sha1_cs_mac_s2, blk, len, seq, blk+len);
}
static int sha1_verify(unsigned char *blk, int len, unsigned long seq) {
unsigned char correct[20];
sha1_do_hmac(blk, len, seq, correct);
sha1_do_hmac(&sha1_sc_mac_s1, &sha1_sc_mac_s2, blk, len, seq, correct);
return !memcmp(correct, blk+len, 20);
}
struct ssh_mac ssh_sha1 = {
sha1_sesskey,
sha1_cskey, sha1_sckey,
sha1_generate,
sha1_verify,
"hmac-sha1",