srp_vfy.c

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/* crypto/srp/srp_vfy.c */
/* Written by Christophe Renou ([email protected]) with 
 * the precious help of Peter Sylvester ([email protected]) 
 * 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
 *    [email protected].
 *
 * 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
 * ([email protected]).  This product includes software written by Tim
 * Hudson ([email protected]).
 *
 */
#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, const char *src)
    {
    char *loc;
    int i, j;
    int size;

    while(*src && (*src == ' ' || *src == '\t' || *src == '\n'))
        ++src;
    size = strlen(src);
    i = 0;
    while(i < size)
        {
        loc = strchr(b64table, src[i]);
        if(loc == (char *) 0) break;
        else a[i] = loc - b64table;
        ++i;
        }
    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(a[j] == 0 && j <= size) ++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;
    }

static 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;

    if (strlen(s) > MAX_LEN || strlen(v) > MAX_LEN) 
        return 0; 
    len = t_fromb64(tmp, v);
    if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)) )
        return 0;
    len = t_fromb64(tmp, s);
    return ((vinfo->s = BN_bin2bn(tmp, len, NULL)) != NULL) ;
    }

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) ;
    }

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;

    if ((newgN->b64_bn = BUF_strdup(ch)) == NULL)
        goto err;

    len = t_fromb64(tmp, ch);
    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 = (char **)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;

    }


SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
    {
    int i;
    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;
    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;
        }
    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;
        
    RAND_pseudo_bytes(digv, SHA_DIGEST_LENGTH);
    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;
    char *vf;
    BIGNUM *N_bn = NULL, *g_bn = NULL, *s = NULL, *v = NULL;
    unsigned char tmp[MAX_LEN];
    unsigned char tmp2[MAX_LEN];
    char * defgNid = NULL;

    if ((user == NULL)||
        (pass == NULL)||
        (salt == NULL)||
        (verifier == NULL))
        goto err;

    if (N)
        {
        if (!(len = t_fromb64(tmp, N))) goto err;
        N_bn = BN_bin2bn(tmp, len, NULL);
        if (!(len = t_fromb64(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)
        {
        RAND_pseudo_bytes(tmp2, SRP_RANDOM_SALT_LEN);

        s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
        }
    else
        {
        if (!(len = t_fromb64(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);
    if (((vf = OPENSSL_malloc(BN_num_bytes(v)*2)) == NULL))
        goto err;
    t_tob64(vf, tmp, BN_num_bytes(v));

    *verifier = vf;
    if (*salt == NULL)
        {
        char *tmp_salt;
        if ((tmp_salt = (char *)OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL)
            {
            OPENSSL_free(vf);
            goto err;
            }
        t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN);
        *salt = tmp_salt;
        }

    result=defgNid;

err:
    if(N)
        {
        BN_free(N_bn);
        BN_free(g_bn);
        }
    return result;
    }

/*
   create a verifier (*salt,*verifier,g and N are 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];

    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)
        {
        RAND_pseudo_bytes(tmp2, SRP_RANDOM_SALT_LEN);

        *salt = BN_bin2bn(tmp2,SRP_RANDOM_SALT_LEN,NULL);
        }

    x = SRP_Calc_x(*salt,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;

err:

    BN_clear_free(x);
    BN_CTX_free(bn_ctx);
    return result;
    }



#endif