/* 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

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#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_SafeZero(state, sizeof(state));

    PORT_SafeZero(outbuf, 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;

}