/* crypto/srp/srp_lib.c */

/*

 * Written by Christophe Renou (christophe.renou@edelweb.fr) with the

 * precious help of Peter Sylvester (peter.sylvester@edelweb.fr) for the

 * EdelKey project and contributed to the OpenSSL project 2004.

 */

/* ====================================================================

 * Copyright (c) 2004 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).

 *

 */

#ifndef OPENSSL_NO_SRP

# include "cryptlib.h"

# include "srp_lcl.h"

# include <openssl/srp.h>

# include <openssl/evp.h>

# if (BN_BYTES == 8)

#  if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__)

#   define bn_pack4(a1,a2,a3,a4) ((a1##UI64<<48)|(a2##UI64<<32)|(a3##UI64<<16)|a4##UI64)

#  elif defined(__arch64__)

#   define bn_pack4(a1,a2,a3,a4) ((a1##UL<<48)|(a2##UL<<32)|(a3##UL<<16)|a4##UL)

#  else

#   define bn_pack4(a1,a2,a3,a4) ((a1##ULL<<48)|(a2##ULL<<32)|(a3##ULL<<16)|a4##ULL)

#  endif

# elif (BN_BYTES == 4)

#  define bn_pack4(a1,a2,a3,a4)  ((a3##UL<<16)|a4##UL), ((a1##UL<<16)|a2##UL)

# else

#  error "unsupported BN_BYTES"

# endif

# include "srp_grps.h"

static BIGNUM *srp_Calc_k(BIGNUM *N, BIGNUM *g)

{

    /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */

    unsigned char digest[SHA_DIGEST_LENGTH];

    unsigned char *tmp;

    EVP_MD_CTX ctxt;

    int longg;

    int longN = BN_num_bytes(N);

    if (BN_ucmp(g, N) >= 0)

        return NULL;

    if ((tmp = OPENSSL_malloc(longN)) == NULL)

        return NULL;

    BN_bn2bin(N, tmp);

    EVP_MD_CTX_init(&ctxt);

    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);

    EVP_DigestUpdate(&ctxt, tmp, longN);

    memset(tmp, 0, longN);

    longg = BN_bn2bin(g, tmp);

    /* use the zeros behind to pad on left */

    EVP_DigestUpdate(&ctxt, tmp + longg, longN - longg);

    EVP_DigestUpdate(&ctxt, tmp, longg);

    OPENSSL_free(tmp);

    EVP_DigestFinal_ex(&ctxt, digest, NULL);

    EVP_MD_CTX_cleanup(&ctxt);

    return BN_bin2bn(digest, sizeof(digest), NULL);

}

BIGNUM *SRP_Calc_u(BIGNUM *A, BIGNUM *B, BIGNUM *N)

{

    /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */

    BIGNUM *u;

    unsigned char cu[SHA_DIGEST_LENGTH];

    unsigned char *cAB;

    EVP_MD_CTX ctxt;

    int longN;

    if ((A == NULL) || (B == NULL) || (N == NULL))

        return NULL;

    if (BN_ucmp(A, N) >= 0 || BN_ucmp(B, N) >= 0)

        return NULL;

    longN = BN_num_bytes(N);

    if ((cAB = OPENSSL_malloc(2 * longN)) == NULL)

        return NULL;

    memset(cAB, 0, longN);

    EVP_MD_CTX_init(&ctxt);

    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);

    EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(A, cAB + longN), longN);

    EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(B, cAB + longN), longN);

    OPENSSL_free(cAB);

    EVP_DigestFinal_ex(&ctxt, cu, NULL);

    EVP_MD_CTX_cleanup(&ctxt);

    if (!(u = BN_bin2bn(cu, sizeof(cu), NULL)))

        return NULL;

    if (!BN_is_zero(u))

        return u;

    BN_free(u);

    return NULL;

}

BIGNUM *SRP_Calc_server_key(BIGNUM *A, BIGNUM *v, BIGNUM *u, BIGNUM *b,

                            BIGNUM *N)

{

    BIGNUM *tmp = NULL, *S = NULL;

    BN_CTX *bn_ctx;

    if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)

        return NULL;

    if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)

        goto err;

    /* S = (A*v**u) ** b */

    if (!BN_mod_exp(tmp, v, u, N, bn_ctx))

        goto err;

    if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))

        goto err;

    S = BN_new();

    if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {

        BN_free(S);

        S = NULL;

    }

 err:

    BN_CTX_free(bn_ctx);

    BN_clear_free(tmp);

    return S;

}

BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, BIGNUM *v)

{

    BIGNUM *kv = NULL, *gb = NULL;

    BIGNUM *B = NULL, *k = NULL;

    BN_CTX *bn_ctx;

    if (b == NULL || N == NULL || g == NULL || v == NULL ||

        (bn_ctx = BN_CTX_new()) == NULL)

        return NULL;

    if ((kv = BN_new()) == NULL ||

        (gb = BN_new()) == NULL || (B = BN_new()) == NULL)

        goto err;

    /* B = g**b + k*v */

    if (!BN_mod_exp(gb, g, b, N, bn_ctx) ||

        !(k = srp_Calc_k(N, g)) ||

        !BN_mod_mul(kv, v, k, N, bn_ctx) ||

        !BN_mod_add(B, gb, kv, N, bn_ctx)) {

        BN_free(B);

        B = NULL;

    }

 err:

    BN_CTX_free(bn_ctx);

    BN_clear_free(kv);

    BN_clear_free(gb);

    BN_free(k);

    return B;

}

BIGNUM *SRP_Calc_x(BIGNUM *s, const char *user, const char *pass)

{

    unsigned char dig[SHA_DIGEST_LENGTH];

    EVP_MD_CTX ctxt;

    unsigned char *cs;

    if ((s == NULL) || (user == NULL) || (pass == NULL))

        return NULL;

    if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)

        return NULL;

    EVP_MD_CTX_init(&ctxt);

    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);

    EVP_DigestUpdate(&ctxt, user, strlen(user));

    EVP_DigestUpdate(&ctxt, ":", 1);

    EVP_DigestUpdate(&ctxt, pass, strlen(pass));

    EVP_DigestFinal_ex(&ctxt, dig, NULL);

    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);

    BN_bn2bin(s, cs);

    EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s));

    OPENSSL_free(cs);

    EVP_DigestUpdate(&ctxt, dig, sizeof(dig));

    EVP_DigestFinal_ex(&ctxt, dig, NULL);

    EVP_MD_CTX_cleanup(&ctxt);

    return BN_bin2bn(dig, sizeof(dig), NULL);

}

BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, BIGNUM *g)

{

    BN_CTX *bn_ctx;

    BIGNUM *A = NULL;

    if (a == NULL || N == NULL || g == NULL ||

        (bn_ctx = BN_CTX_new()) == NULL)

        return NULL;

    if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {

        BN_free(A);

        A = NULL;

    }

    BN_CTX_free(bn_ctx);

    return A;

}

BIGNUM *SRP_Calc_client_key(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x,

                            BIGNUM *a, BIGNUM *u)

{

    BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;

    BN_CTX *bn_ctx;

    if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL

        || a == NULL || (bn_ctx = BN_CTX_new()) == NULL)

        return NULL;

    if ((tmp = BN_new()) == NULL ||

        (tmp2 = BN_new()) == NULL ||

        (tmp3 = BN_new()) == NULL)

        goto err;

    if (!BN_mod_exp(tmp, g, x, N, bn_ctx))

        goto err;

    if (!(k = srp_Calc_k(N, g)))

        goto err;

    if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))

        goto err;

    if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))

        goto err;

    if (!BN_mul(tmp3, u, x, bn_ctx))

        goto err;

    if (!BN_add(tmp2, a, tmp3))

        goto err;

    K = BN_new();

    if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {

        BN_free(K);

        K = NULL;

    }

 err:

    BN_CTX_free(bn_ctx);

    BN_clear_free(tmp);

    BN_clear_free(tmp2);

    BN_clear_free(tmp3);

    BN_free(k);

    return K;

}

int SRP_Verify_B_mod_N(BIGNUM *B, BIGNUM *N)

{

    BIGNUM *r;

    BN_CTX *bn_ctx;

    int ret = 0;

    if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)

        return 0;

    if ((r = BN_new()) == NULL)

        goto err;

    /* Checks if B % N == 0 */

    if (!BN_nnmod(r, B, N, bn_ctx))

        goto err;

    ret = !BN_is_zero(r);

 err:

    BN_CTX_free(bn_ctx);

    BN_free(r);

    return ret;

}

int SRP_Verify_A_mod_N(BIGNUM *A, BIGNUM *N)

{

    /* Checks if A % N == 0 */

    return SRP_Verify_B_mod_N(A, N);

}

/*

 * Check if G and N are kwown parameters. The values have been generated

 * from the ietf-tls-srp draft version 8

 */

char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N)

{

    size_t i;

    if ((g == NULL) || (N == NULL))

        return 0;

    srp_bn_print(g);

    srp_bn_print(N);

    for (i = 0; i < KNOWN_GN_NUMBER; i++) {

        if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)

            return knowngN[i].id;

    }

    return NULL;

}

SRP_gN *SRP_get_default_gN(const char *id)

{

    size_t i;

    if (id == NULL)

        return knowngN;

    for (i = 0; i < KNOWN_GN_NUMBER; i++) {

        if (strcmp(knowngN[i].id, id) == 0)

            return knowngN + i;

    }

    return NULL;

}

#endif