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/* tlsprfalg.c - TLS Pseudo Random Function (PRF) implementation
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif
#include "blapi.h"
#include "hasht.h"
#include "alghmac.h"
#define PHASH_STATE_MAX_LEN HASH_LENGTH_MAX
/* TLS P_hash function */
SECStatus
TLS_P_hash(HASH_HashType hashType, const SECItem *secret, const char *label,
SECItem *seed, SECItem *result, PRBool isFIPS)
{
unsigned char state[PHASH_STATE_MAX_LEN];
unsigned char outbuf[PHASH_STATE_MAX_LEN];
unsigned int state_len = 0, label_len = 0, outbuf_len = 0, chunk_size;
unsigned int remaining;
unsigned char *res;
SECStatus status;
HMACContext *cx;
SECStatus rv = SECFailure;
const SECHashObject *hashObj = HASH_GetRawHashObject(hashType);
PORT_Assert((secret != NULL) && (secret->data != NULL || !secret->len));
PORT_Assert((seed != NULL) && (seed->data != NULL));
PORT_Assert((result != NULL) && (result->data != NULL));
remaining = result->len;
res = result->data;
if (label != NULL)
label_len = PORT_Strlen(label);
cx = HMAC_Create(hashObj, secret->data, secret->len, isFIPS);
if (cx == NULL)
goto loser;
/* initialize the state = A(1) = HMAC_hash(secret, seed) */
HMAC_Begin(cx);
HMAC_Update(cx, (unsigned char *)label, label_len);
HMAC_Update(cx, seed->data, seed->len);
status = HMAC_Finish(cx, state, &state_len, sizeof(state));
if (status != SECSuccess)
goto loser;
/* generate a block at a time until we're done */
while (remaining > 0) {
HMAC_Begin(cx);
HMAC_Update(cx, state, state_len);
if (label_len)
HMAC_Update(cx, (unsigned char *)label, label_len);
HMAC_Update(cx, seed->data, seed->len);
status = HMAC_Finish(cx, outbuf, &outbuf_len, sizeof(outbuf));
if (status != SECSuccess)
goto loser;
/* Update the state = A(i) = HMAC_hash(secret, A(i-1)) */
HMAC_Begin(cx);
HMAC_Update(cx, state, state_len);
status = HMAC_Finish(cx, state, &state_len, sizeof(state));
if (status != SECSuccess)
goto loser;
chunk_size = PR_MIN(outbuf_len, remaining);
PORT_Memcpy(res, &outbuf, chunk_size);
res += chunk_size;
remaining -= chunk_size;
}
rv = SECSuccess;
loser:
/* clear out state so it's not left on the stack */
if (cx)
HMAC_Destroy(cx, PR_TRUE);
PORT_Memset(state, 0, sizeof(state));
PORT_Memset(outbuf, 0, sizeof(outbuf));
return rv;
}
SECStatus
TLS_PRF(const SECItem *secret, const char *label, SECItem *seed,
SECItem *result, PRBool isFIPS)
{
SECStatus rv = SECFailure, status;
unsigned int i;
SECItem tmp = { siBuffer, NULL, 0 };
SECItem S1;
SECItem S2;
PORT_Assert((secret != NULL) && (secret->data != NULL || !secret->len));
PORT_Assert((seed != NULL) && (seed->data != NULL));
PORT_Assert((result != NULL) && (result->data != NULL));
S1.type = siBuffer;
S1.len = (secret->len / 2) + (secret->len & 1);
S1.data = secret->data;
S2.type = siBuffer;
S2.len = S1.len;
S2.data = secret->data + (secret->len - S2.len);
tmp.data = (unsigned char *)PORT_Alloc(result->len);
if (tmp.data == NULL)
goto loser;
tmp.len = result->len;
status = TLS_P_hash(HASH_AlgMD5, &S1, label, seed, result, isFIPS);
if (status != SECSuccess)
goto loser;
status = TLS_P_hash(HASH_AlgSHA1, &S2, label, seed, &tmp, isFIPS);
if (status != SECSuccess)
goto loser;
for (i = 0; i < result->len; i++)
result->data[i] ^= tmp.data[i];
rv = SECSuccess;
loser:
if (tmp.data != NULL)
PORT_ZFree(tmp.data, tmp.len);
return rv;
}