j3d1/tinc
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Proper use of PRF.

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This commit is contained in:
Guus Sliepen 2011-07-03 16:30:49 +02:00
parent 82f00ea07b
commit ac163120d7
1 changed files with 24 additions and 24 deletions
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48
src/protocol_key.c
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@ -279,11 +279,8 @@ bool ans_key_h(connection_t *c, char *request) {
from->outcompression = compression; from->outcompression = compression;
/* ECDH or old-style key exchange? */ /* ECDH or old-style key exchange? */
/* TODO: look at SSH and TLS to see how they derive cipher and HMAC keys from shared secret properly */
if(!strncmp(key, "ECDH:", 5)) { if(!strncmp(key, "ECDH:", 5)) {
logger(LOG_DEBUG, "Got ECDH key from %s", from->name);
keylen = (strlen(key) - 5) / 2; keylen = (strlen(key) - 5) / 2;
if(keylen != ECDH_SIZE) { if(keylen != ECDH_SIZE) {
@ -297,7 +294,6 @@ bool ans_key_h(connection_t *c, char *request) {
} }
if(!from->ecdh) { if(!from->ecdh) {
logger(LOG_DEBUG, "Woops, we didn't generate our public key yet");
from->status.ecdh = true; from->status.ecdh = true;
if(!send_ans_key(from)) if(!send_ans_key(from))
return false; return false;
@ -313,22 +309,23 @@ bool ans_key_h(connection_t *c, char *request) {
/* Update our crypto end */ /* Update our crypto end */
size_t mykeylen = cipher_keylength(&myself->incipher); size_t mykeylen = cipher_keylength(&myself->incipher);
keylen = cipher_keylength(&from->outcipher); size_t hiskeylen = cipher_keylength(&from->outcipher);
char *mykey; char *mykey;
char *seed = NULL; char *hiskey;
char *seed;
if(strcmp(myself->name, from->name) < 0) { if(strcmp(myself->name, from->name) < 0) {
logger(LOG_DEBUG, "Using left half of shared secret");
mykey = key; mykey = key;
xasprintf(&seed, "tinc key expansion %s %s", myself->name, from->name); hiskey = key + mykeylen * 2;
xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
} else { } else {
logger(LOG_DEBUG, "Using right half of shared secret"); mykey = key + hiskeylen * 2;
mykey = key + keylen; hiskey = key;
xasprintf(&seed, "tinc key expansion %s %s", from->name, myself->name); xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name);
} }
if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, keylen + mykeylen)) if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
return false; return false;
free(seed); free(seed);
@ -338,7 +335,10 @@ bool ans_key_h(connection_t *c, char *request) {
from->incompression = myself->incompression; from->incompression = myself->incompression;
cipher_set_key(&from->incipher, mykey, true); cipher_set_key(&from->incipher, mykey, true);
digest_set_key(&from->indigest, mykey, mykeylen); digest_set_key(&from->indigest, mykey + mykeylen, mykeylen);
cipher_set_key(&from->outcipher, hiskey, false);
digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen);
// Reset sequence number and late packet window // Reset sequence number and late packet window
mykeyused = true; mykeyused = true;
@ -347,22 +347,22 @@ bool ans_key_h(connection_t *c, char *request) {
memset(from->late, 0, replaywin); memset(from->late, 0, replaywin);
if(strcmp(myself->name, from->name) < 0) if(strcmp(myself->name, from->name) < 0)
memmove(key, key + mykeylen, keylen); memmove(key, key + mykeylen * 2, hiskeylen * 2);
} else { } else {
keylen = strlen(key) / 2; keylen = strlen(key) / 2;
hex2bin(key, key, keylen); hex2bin(key, key, keylen);
if(keylen != cipher_keylength(&from->outcipher)) {
logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
return false;
}
/* Update our copy of the origin's packet key */
cipher_set_key(&from->outcipher, key, false);
digest_set_key(&from->outdigest, key, keylen);
} }
/* Update our copy of the origin's packet key */
if(keylen != cipher_keylength(&from->outcipher)) {
logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
return false;
}
cipher_set_key(&from->outcipher, key, false);
digest_set_key(&from->outdigest, key, keylen);
from->status.validkey = true; from->status.validkey = true;
from->sent_seqno = 0; from->sent_seqno = 0;