tls1_prf.c

/*
 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
 * 2016.
 */
/* ====================================================================
 * Copyright (c) 2015 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/kdf.h>
#include <openssl/evp.h>
#include "internal/evp_int.h"

static int tls1_prf_alg(const EVP_MD *md,
                        const unsigned char *sec, size_t slen,
                        const unsigned char *seed, size_t seed_len,
                        unsigned char *out, size_t olen);

#define TLS1_PRF_MAXBUF 1024

/* TLS KDF pkey context structure */

typedef struct {
    /* Digest to use for PRF */
    const EVP_MD *md;
    /* Secret value to use for PRF */
    unsigned char *sec;
    size_t seclen;
    /* Buffer of concatenated seed data */
    unsigned char seed[TLS1_PRF_MAXBUF];
    size_t seedlen;
} TLS1_PRF_PKEY_CTX;

static int pkey_tls1_prf_init(EVP_PKEY_CTX *ctx)
{
    TLS1_PRF_PKEY_CTX *kctx;

    kctx = OPENSSL_zalloc(sizeof(*kctx));
    if (kctx == NULL)
        return 0;
    ctx->data = kctx;

    return 1;
}

static void pkey_tls1_prf_cleanup(EVP_PKEY_CTX *ctx)
{
    TLS1_PRF_PKEY_CTX *kctx = ctx->data;
    OPENSSL_clear_free(kctx->sec, kctx->seclen);
    OPENSSL_cleanse(kctx->seed, kctx->seedlen);
    OPENSSL_free(kctx);
}

static int pkey_tls1_prf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
    TLS1_PRF_PKEY_CTX *kctx = ctx->data;
    switch (type) {
    case EVP_PKEY_CTRL_TLS_MD:
        kctx->md = p2;
        return 1;

    case EVP_PKEY_CTRL_TLS_SECRET:
        if (p1 < 0)
            return 0;
        if (kctx->sec != NULL)
            OPENSSL_clear_free(kctx->sec, kctx->seclen);
        OPENSSL_cleanse(kctx->seed, kctx->seedlen);
        kctx->seedlen = 0;
        kctx->sec = OPENSSL_memdup(p2, p1);
        if (kctx->sec == NULL)
            return 0;
        kctx->seclen  = p1;
        return 1;

    case EVP_PKEY_CTRL_TLS_SEED:
        if (p1 == 0 || p2 == NULL)
            return 1;
        if (p1 < 0 || p1 > (int)(TLS1_PRF_MAXBUF - kctx->seedlen))
            return 0;
        memcpy(kctx->seed + kctx->seedlen, p2, p1);
        kctx->seedlen += p1;
        return 1;

    default:
        return -2;

    }
}

static int pkey_tls1_prf_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
                                size_t *keylen)
{
    TLS1_PRF_PKEY_CTX *kctx = ctx->data;
    if (kctx->md == NULL || kctx->sec == NULL || kctx->seedlen == 0)
        return 0;
    return tls1_prf_alg(kctx->md, kctx->sec, kctx->seclen,
                        kctx->seed, kctx->seedlen,
                        key, *keylen);
}

const EVP_PKEY_METHOD tls1_prf_pkey_meth = {
    EVP_PKEY_TLS1_PRF,
    0,
    pkey_tls1_prf_init,
    0,
    pkey_tls1_prf_cleanup,

    0, 0,
    0, 0,

    0,
    0,

    0,
    0,

    0, 0,

    0, 0, 0, 0,

    0, 0,

    0, 0,

    0,
    pkey_tls1_prf_derive,
    pkey_tls1_prf_ctrl,
    0
};

static int tls1_prf_P_hash(const EVP_MD *md,
                           const unsigned char *sec, size_t sec_len,
                           const unsigned char *seed, size_t seed_len,
                           unsigned char *out, size_t olen)
{
    int chunk;
    EVP_MD_CTX *ctx = NULL, *ctx_tmp = NULL, *ctx_init = NULL;
    EVP_PKEY *mac_key = NULL;
    unsigned char A1[EVP_MAX_MD_SIZE];
    size_t A1_len;
    int ret = 0;

    chunk = EVP_MD_size(md);
    OPENSSL_assert(chunk >= 0);

    ctx = EVP_MD_CTX_new();
    ctx_tmp = EVP_MD_CTX_new();
    ctx_init = EVP_MD_CTX_new();
    if (ctx == NULL || ctx_tmp == NULL || ctx_init == NULL)
        goto err;
    EVP_MD_CTX_set_flags(ctx_init, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);
    mac_key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, sec, sec_len);
    if (mac_key == NULL)
        goto err;
    if (!EVP_DigestSignInit(ctx_init, NULL, md, NULL, mac_key))
        goto err;
    if (!EVP_MD_CTX_copy_ex(ctx, ctx_init))
        goto err;
    if (seed != NULL && !EVP_DigestSignUpdate(ctx, seed, seed_len))
        goto err;
    if (!EVP_DigestSignFinal(ctx, A1, &A1_len))
        goto err;

    for (;;) {
        /* Reinit mac contexts */
        if (!EVP_MD_CTX_copy_ex(ctx, ctx_init))
            goto err;
        if (!EVP_DigestSignUpdate(ctx, A1, A1_len))
            goto err;
        if (olen > (size_t)chunk && !EVP_MD_CTX_copy_ex(ctx_tmp, ctx))
            goto err;
        if (seed && !EVP_DigestSignUpdate(ctx, seed, seed_len))
            goto err;

        if (olen > (size_t)chunk) {
            size_t mac_len;
            if (!EVP_DigestSignFinal(ctx, out, &mac_len))
                goto err;
            out += mac_len;
            olen -= mac_len;
            /* calc the next A1 value */
            if (!EVP_DigestSignFinal(ctx_tmp, A1, &A1_len))
                goto err;
        } else {                /* last one */

            if (!EVP_DigestSignFinal(ctx, A1, &A1_len))
                goto err;
            memcpy(out, A1, olen);
            break;
        }
    }
    ret = 1;
 err:
    EVP_PKEY_free(mac_key);
    EVP_MD_CTX_free(ctx);
    EVP_MD_CTX_free(ctx_tmp);
    EVP_MD_CTX_free(ctx_init);
    OPENSSL_cleanse(A1, sizeof(A1));
    return ret;
}

static int tls1_prf_alg(const EVP_MD *md,
                        const unsigned char *sec, size_t slen,
                        const unsigned char *seed, size_t seed_len,
                        unsigned char *out, size_t olen)
{

    if (EVP_MD_type(md) == NID_md5_sha1) {
        size_t i;
        unsigned char *tmp;
        if (!tls1_prf_P_hash(EVP_md5(), sec, slen/2 + (slen & 1),
                         seed, seed_len, out, olen))
            return 0;

        tmp = OPENSSL_malloc(olen);
        if (tmp == NULL)
            return 0;
        if (!tls1_prf_P_hash(EVP_sha1(), sec + slen/2, slen/2 + (slen & 1),
                         seed, seed_len, tmp, olen)) {
            OPENSSL_clear_free(tmp, olen);
            return 0;
        }
        for (i = 0; i < olen; i++)
            out[i] ^= tmp[i];
        OPENSSL_clear_free(tmp, olen);
        return 1;
    }
    if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))
        return 0;

    return 1;
}