/* crypto/srp/srp_vfy.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>

# include <openssl/buffer.h>

# include <openssl/rand.h>

# include <openssl/txt_db.h>

# define SRP_RANDOM_SALT_LEN 20

# define MAX_LEN 2500

static char b64table[] =

    "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";

/*

 * the following two conversion routines have been inspired by code from

 * Stanford

 */

/*

 * Convert a base64 string into raw byte array representation.

 */

static int t_fromb64(unsigned char *a, size_t alen, const char *src)

{

    char *loc;

    int i, j;

    int size;

    if (alen == 0 || alen > INT_MAX)

        return -1;

    while (*src && (*src == ' ' || *src == '\t' || *src == '\n'))

        ++src;

    size = strlen(src);

    if (size < 0 || size >= (int)alen)

        return -1;

    i = 0;

    while (i < size) {

        loc = strchr(b64table, src[i]);

        if (loc == (char *)0)

            break;

        else

            a[i] = loc - b64table;

        ++i;

    }

    /* if nothing valid to process we have a zero length response */

    if (i == 0)

        return 0;

    size = i;

    i = size - 1;

    j = size;

    while (1) {

        a[j] = a[i];

        if (--i < 0)

            break;

        a[j] |= (a[i] & 3) << 6;

        --j;

        a[j] = (unsigned char)((a[i] & 0x3c) >> 2);

        if (--i < 0)

            break;

        a[j] |= (a[i] & 0xf) << 4;

        --j;

        a[j] = (unsigned char)((a[i] & 0x30) >> 4);

        if (--i < 0)

            break;

        a[j] |= (a[i] << 2);

        a[--j] = 0;

        if (--i < 0)

            break;

    }

    while (j <= size && a[j] == 0)

        ++j;

    i = 0;

    while (j <= size)

        a[i++] = a[j++];

    return i;

}

/*

 * Convert a raw byte string into a null-terminated base64 ASCII string.

 */

static char *t_tob64(char *dst, const unsigned char *src, int size)

{

    int c, pos = size % 3;

    unsigned char b0 = 0, b1 = 0, b2 = 0, notleading = 0;

    char *olddst = dst;

    switch (pos) {

    case 1:

        b2 = src[0];

        break;

    case 2:

        b1 = src[0];

        b2 = src[1];

        break;

    }

    while (1) {

        c = (b0 & 0xfc) >> 2;

        if (notleading || c != 0) {

            *dst++ = b64table[c];

            notleading = 1;

        }

        c = ((b0 & 3) << 4) | ((b1 & 0xf0) >> 4);

        if (notleading || c != 0) {

            *dst++ = b64table[c];

            notleading = 1;

        }

        c = ((b1 & 0xf) << 2) | ((b2 & 0xc0) >> 6);

        if (notleading || c != 0) {

            *dst++ = b64table[c];

            notleading = 1;

        }

        c = b2 & 0x3f;

        if (notleading || c != 0) {

            *dst++ = b64table[c];

            notleading = 1;

        }

        if (pos >= size)

            break;

        else {

            b0 = src[pos++];

            b1 = src[pos++];

            b2 = src[pos++];

        }

    }

    *dst++ = '\0';

    return olddst;

}

void SRP_user_pwd_free(SRP_user_pwd *user_pwd)

{

    if (user_pwd == NULL)

        return;

    BN_free(user_pwd->s);

    BN_clear_free(user_pwd->v);

    OPENSSL_free(user_pwd->id);

    OPENSSL_free(user_pwd->info);

    OPENSSL_free(user_pwd);

}

static SRP_user_pwd *SRP_user_pwd_new()

{

    SRP_user_pwd *ret = OPENSSL_malloc(sizeof(SRP_user_pwd));

    if (ret == NULL)

        return NULL;

    ret->N = NULL;

    ret->g = NULL;

    ret->s = NULL;

    ret->v = NULL;

    ret->id = NULL;

    ret->info = NULL;

    return ret;

}

static void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,

                                const BIGNUM *N)

{

    vinfo->N = N;

    vinfo->g = g;

}

static int SRP_user_pwd_set_ids(SRP_user_pwd *vinfo, const char *id,

                                const char *info)

{

    if (id != NULL && NULL == (vinfo->id = BUF_strdup(id)))

        return 0;

    return (info == NULL || NULL != (vinfo->info = BUF_strdup(info)));

}

static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,

                               const char *v)

{

    unsigned char tmp[MAX_LEN];

    int len;

    vinfo->v = NULL;

    vinfo->s = NULL;

    len = t_fromb64(tmp, sizeof(tmp), v);

    if (len < 0)

        return 0;

    if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))

        return 0;

    len = t_fromb64(tmp, sizeof(tmp), s);

    if (len < 0)

        goto err;

    vinfo->s = BN_bin2bn(tmp, len, NULL);

    if (vinfo->s == NULL)

        goto err;

    return 1;

 err:

    BN_free(vinfo->v);

    vinfo->v = NULL;

    return 0;

}

static int SRP_user_pwd_set_sv_BN(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)

{

    vinfo->v = v;

    vinfo->s = s;

    return (vinfo->s != NULL && vinfo->v != NULL);

}

static SRP_user_pwd *srp_user_pwd_dup(SRP_user_pwd *src)

{

    SRP_user_pwd *ret;

    if (src == NULL)

        return NULL;

    if ((ret = SRP_user_pwd_new()) == NULL)

        return NULL;

    SRP_user_pwd_set_gN(ret, src->g, src->N);

    if (!SRP_user_pwd_set_ids(ret, src->id, src->info)

        || !SRP_user_pwd_set_sv_BN(ret, BN_dup(src->s), BN_dup(src->v))) {

            SRP_user_pwd_free(ret);

            return NULL;

    }

    return ret;

}

SRP_VBASE *SRP_VBASE_new(char *seed_key)

{

    SRP_VBASE *vb = (SRP_VBASE *)OPENSSL_malloc(sizeof(SRP_VBASE));

    if (vb == NULL)

        return NULL;

    if (!(vb->users_pwd = sk_SRP_user_pwd_new_null()) ||

        !(vb->gN_cache = sk_SRP_gN_cache_new_null())) {

        OPENSSL_free(vb);

        return NULL;

    }

    vb->default_g = NULL;

    vb->default_N = NULL;

    vb->seed_key = NULL;

    if ((seed_key != NULL) && (vb->seed_key = BUF_strdup(seed_key)) == NULL) {

        sk_SRP_user_pwd_free(vb->users_pwd);

        sk_SRP_gN_cache_free(vb->gN_cache);

        OPENSSL_free(vb);

        return NULL;

    }

    return vb;

}

int SRP_VBASE_free(SRP_VBASE *vb)

{

    sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);

    sk_SRP_gN_cache_free(vb->gN_cache);

    OPENSSL_free(vb->seed_key);

    OPENSSL_free(vb);

    return 0;

}

static SRP_gN_cache *SRP_gN_new_init(const char *ch)

{

    unsigned char tmp[MAX_LEN];

    int len;

    SRP_gN_cache *newgN =

        (SRP_gN_cache *)OPENSSL_malloc(sizeof(SRP_gN_cache));

    if (newgN == NULL)

        return NULL;

    len = t_fromb64(tmp, sizeof(tmp), ch);

    if (len < 0)

        goto err;

    if ((newgN->b64_bn = BUF_strdup(ch)) == NULL)

        goto err;

    if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))

        return newgN;

    OPENSSL_free(newgN->b64_bn);

 err:

    OPENSSL_free(newgN);

    return NULL;

}

static void SRP_gN_free(SRP_gN_cache *gN_cache)

{

    if (gN_cache == NULL)

        return;

    OPENSSL_free(gN_cache->b64_bn);

    BN_free(gN_cache->bn);

    OPENSSL_free(gN_cache);

}

static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)

{

    int i;

    SRP_gN *gN;

    if (gN_tab != NULL)

        for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {

            gN = sk_SRP_gN_value(gN_tab, i);

            if (gN && (id == NULL || strcmp(gN->id, id) == 0))

                return gN;

        }

    return SRP_get_default_gN(id);

}

static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)

{

    int i;

    if (gN_cache == NULL)

        return NULL;

    /* search if we have already one... */

    for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {

        SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);

        if (strcmp(cache->b64_bn, ch) == 0)

            return cache->bn;

    }

    {                           /* it is the first time that we find it */

        SRP_gN_cache *newgN = SRP_gN_new_init(ch);

        if (newgN) {

            if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)

                return newgN->bn;

            SRP_gN_free(newgN);

        }

    }

    return NULL;

}

/*

 * this function parses verifier file. Format is:

 * string(index):base64(N):base64(g):0

 * string(username):base64(v):base64(salt):int(index)

 */

int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)

{

    int error_code;

    STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();

    char *last_index = NULL;

    int i;

    char **pp;

    SRP_gN *gN = NULL;

    SRP_user_pwd *user_pwd = NULL;

    TXT_DB *tmpdb = NULL;

    BIO *in = BIO_new(BIO_s_file());

    error_code = SRP_ERR_OPEN_FILE;

    if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)

        goto err;

    error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;

    if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)

        goto err;

    error_code = SRP_ERR_MEMORY;

    if (vb->seed_key) {

        last_index = SRP_get_default_gN(NULL)->id;

    }

    for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {

        pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);

        if (pp[DB_srptype][0] == DB_SRP_INDEX) {

            /*

             * we add this couple in the internal Stack

             */

            if ((gN = (SRP_gN *) OPENSSL_malloc(sizeof(SRP_gN))) == NULL)

                goto err;

            if (!(gN->id = BUF_strdup(pp[DB_srpid]))

                || !(gN->N =

                     SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))

                || !(gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))

                || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)

                goto err;

            gN = NULL;

            if (vb->seed_key != NULL) {

                last_index = pp[DB_srpid];

            }

        } else if (pp[DB_srptype][0] == DB_SRP_VALID) {

            /* it is a user .... */

            SRP_gN *lgN;

            if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {

                error_code = SRP_ERR_MEMORY;

                if ((user_pwd = SRP_user_pwd_new()) == NULL)

                    goto err;

                SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);

                if (!SRP_user_pwd_set_ids

                    (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))

                    goto err;

                error_code = SRP_ERR_VBASE_BN_LIB;

                if (!SRP_user_pwd_set_sv

                    (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))

                    goto err;

                if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)

                    goto err;

                user_pwd = NULL; /* abandon responsability */

            }

        }

    }

    if (last_index != NULL) {

        /* this means that we want to simulate a default user */

        if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {

            error_code = SRP_ERR_VBASE_BN_LIB;

            goto err;

        }

        vb->default_g = gN->g;

        vb->default_N = gN->N;

        gN = NULL;

    }

    error_code = SRP_NO_ERROR;

 err:

    /*

     * there may be still some leaks to fix, if this fails, the application

     * terminates most likely

     */

    if (gN != NULL) {

        OPENSSL_free(gN->id);

        OPENSSL_free(gN);

    }

    SRP_user_pwd_free(user_pwd);

    if (tmpdb)

        TXT_DB_free(tmpdb);

    if (in)

        BIO_free_all(in);

    sk_SRP_gN_free(SRP_gN_tab);

    return error_code;

}

static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)

{

    int i;

    SRP_user_pwd *user;

    if (vb == NULL)

        return NULL;

    for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {

        user = sk_SRP_user_pwd_value(vb->users_pwd, i);

        if (strcmp(user->id, username) == 0)

            return user;

    }

    return NULL;

}

/*

 * This method ignores the configured seed and fails for an unknown user.

 * Ownership of the returned pointer is not released to the caller.

 * In other words, caller must not free the result.

 */

SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)

{

    return find_user(vb, username);

}

/*

 * Ownership of the returned pointer is released to the caller.

 * In other words, caller must free the result once done.

 */

SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username)

{

    SRP_user_pwd *user;

    unsigned char digv[SHA_DIGEST_LENGTH];

    unsigned char digs[SHA_DIGEST_LENGTH];

    EVP_MD_CTX ctxt;

    if (vb == NULL)

        return NULL;

    if ((user = find_user(vb, username)) != NULL)

        return srp_user_pwd_dup(user);

    if ((vb->seed_key == NULL) ||

        (vb->default_g == NULL) || (vb->default_N == NULL))

        return NULL;

/* if the user is unknown we set parameters as well if we have a seed_key */

    if ((user = SRP_user_pwd_new()) == NULL)

        return NULL;

    SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);

    if (!SRP_user_pwd_set_ids(user, username, NULL))

        goto err;

    if (RAND_bytes(digv, SHA_DIGEST_LENGTH) <= 0)

        goto err;

    EVP_MD_CTX_init(&ctxt);

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

    EVP_DigestUpdate(&ctxt, vb->seed_key, strlen(vb->seed_key));

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

    EVP_DigestFinal_ex(&ctxt, digs, NULL);

    EVP_MD_CTX_cleanup(&ctxt);

    if (SRP_user_pwd_set_sv_BN

        (user, BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),

         BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))

        return user;

 err:SRP_user_pwd_free(user);

    return NULL;

}

/*

 * create a verifier (*salt,*verifier,g and N are in base64)

 */

char *SRP_create_verifier(const char *user, const char *pass, char **salt,

                          char **verifier, const char *N, const char *g)

{

    int len;

    char *result = NULL, *vf = NULL;

    BIGNUM *N_bn = NULL, *g_bn = NULL, *s = NULL, *v = NULL;

    unsigned char tmp[MAX_LEN];

    unsigned char tmp2[MAX_LEN];

    char *defgNid = NULL;

    int vfsize = 0;

    if ((user == NULL) ||

        (pass == NULL) || (salt == NULL) || (verifier == NULL))

        goto err;

    if (N) {

        if (!(len = t_fromb64(tmp, sizeof(tmp), N)))

            goto err;

        N_bn = BN_bin2bn(tmp, len, NULL);

        if (!(len = t_fromb64(tmp, sizeof(tmp), g)))

            goto err;

        g_bn = BN_bin2bn(tmp, len, NULL);

        defgNid = "*";

    } else {

        SRP_gN *gN = SRP_get_gN_by_id(g, NULL);

        if (gN == NULL)

            goto err;

        N_bn = gN->N;

        g_bn = gN->g;

        defgNid = gN->id;

    }

    if (*salt == NULL) {

        if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)

            goto err;

        s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);

    } else {

        if (!(len = t_fromb64(tmp2, sizeof(tmp2), *salt)))

            goto err;

        s = BN_bin2bn(tmp2, len, NULL);

    }

    if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))

        goto err;

    BN_bn2bin(v, tmp);

    vfsize = BN_num_bytes(v) * 2;

    if (((vf = OPENSSL_malloc(vfsize)) == NULL))

        goto err;

    t_tob64(vf, tmp, BN_num_bytes(v));

    if (*salt == NULL) {

        char *tmp_salt;

        if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {

            goto err;

        }

        t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN);

        *salt = tmp_salt;

    }

    *verifier = vf;

    vf = NULL;

    result = defgNid;

 err:

    if (N) {

        BN_free(N_bn);

        BN_free(g_bn);

    }

    if (vf != NULL)

        OPENSSL_cleanse(vf, vfsize);

    OPENSSL_free(vf);

    BN_clear_free(s);

    BN_clear_free(v);

    return result;

}

/*

 * create a verifier (*salt,*verifier,g and N are BIGNUMs). If *salt != NULL

 * then the provided salt will be used. On successful exit *verifier will point

 * to a newly allocated BIGNUM containing the verifier and (if a salt was not

 * provided) *salt will be populated with a newly allocated BIGNUM containing a

 * random salt.

 * The caller is responsible for freeing the allocated *salt and *verifier

 * BIGNUMS.

 */

int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,

                           BIGNUM **verifier, BIGNUM *N, BIGNUM *g)

{

    int result = 0;

    BIGNUM *x = NULL;

    BN_CTX *bn_ctx = BN_CTX_new();

    unsigned char tmp2[MAX_LEN];

    BIGNUM *salttmp = NULL;

    if ((user == NULL) ||

        (pass == NULL) ||

        (salt == NULL) ||

        (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))

        goto err;

    srp_bn_print(N);

    srp_bn_print(g);

    if (*salt == NULL) {

        if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)

            goto err;

        salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);

    } else {

        salttmp = *salt;

    }

    x = SRP_Calc_x(salttmp, user, pass);

    *verifier = BN_new();

    if (*verifier == NULL)

        goto err;

    if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {

        BN_clear_free(*verifier);

        goto err;

    }

    srp_bn_print(*verifier);

    result = 1;

    *salt = salttmp;

 err:

    if (*salt != salttmp)

        BN_clear_free(salttmp);

    BN_clear_free(x);

    BN_CTX_free(bn_ctx);

    return result;

}

#endif