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openssl/crypto/srp/srp_vfy.c

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/*
* Copyright 2004-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2004, EdelKey Project. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*
* Originally written by Christophe Renou and Peter Sylvester,
* for the EdelKey project.
*/
#ifndef OPENSSL_NO_SRP
# include "internal/cryptlib.h"
# include "crypto/evp.h"
# include <openssl/sha.h>
# include <openssl/srp.h>
# include <openssl/evp.h>
# include <openssl/buffer.h>
# include <openssl/rand.h>
# include <openssl/txt_db.h>
# include <openssl/err.h>
# define SRP_RANDOM_SALT_LEN 20
# define MAX_LEN 2500
/*
* Note that SRP uses its own variant of base 64 encoding. A different base64
* alphabet is used and no padding '=' characters are added. Instead we pad to
* the front with 0 bytes and subsequently strip off leading encoded padding.
* This variant is used for compatibility with other SRP implementations -
* notably libsrp, but also others. It is also required for backwards
* compatibility in order to load verifier files from other OpenSSL versions.
*/
/*
* Convert a base64 string into raw byte array representation.
* Returns the length of the decoded data, or -1 on error.
*/
static int t_fromb64(unsigned char *a, size_t alen, const char *src)
{
EVP_ENCODE_CTX *ctx;
int outl = 0, outl2 = 0;
size_t size, padsize;
const unsigned char *pad = (const unsigned char *)"00";
while (*src == ' ' || *src == '\t' || *src == '\n')
++src;
size = strlen(src);
padsize = 4 - (size & 3);
padsize &= 3;
/* Four bytes in src become three bytes output. */
if (size > INT_MAX || ((size + padsize) / 4) * 3 > alen)
return -1;
ctx = EVP_ENCODE_CTX_new();
if (ctx == NULL)
return -1;
/*
* This should never occur because 1 byte of data always requires 2 bytes of
* encoding, i.e.
* 0 bytes unencoded = 0 bytes encoded
* 1 byte unencoded = 2 bytes encoded
* 2 bytes unencoded = 3 bytes encoded
* 3 bytes unencoded = 4 bytes encoded
* 4 bytes unencoded = 6 bytes encoded
* etc
*/
if (padsize == 3) {
outl = -1;
goto err;
}
/* Valid padsize values are now 0, 1 or 2 */
EVP_DecodeInit(ctx);
evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_USE_SRP_ALPHABET);
/* Add any encoded padding that is required */
if (padsize != 0
&& EVP_DecodeUpdate(ctx, a, &outl, pad, padsize) < 0) {
outl = -1;
goto err;
}
if (EVP_DecodeUpdate(ctx, a, &outl2, (const unsigned char *)src, size) < 0) {
outl = -1;
goto err;
}
outl += outl2;
EVP_DecodeFinal(ctx, a + outl, &outl2);
outl += outl2;
/* Strip off the leading padding */
if (padsize != 0) {
if ((int)padsize >= outl) {
outl = -1;
goto err;
}
/*
* If we added 1 byte of padding prior to encoding then we have 2 bytes
* of "real" data which gets spread across 4 encoded bytes like this:
* (6 bits pad)(2 bits pad | 4 bits data)(6 bits data)(6 bits data)
* So 1 byte of pre-encoding padding results in 1 full byte of encoded
* padding.
* If we added 2 bytes of padding prior to encoding this gets encoded
* as:
* (6 bits pad)(6 bits pad)(4 bits pad | 2 bits data)(6 bits data)
* So 2 bytes of pre-encoding padding results in 2 full bytes of encoded
* padding, i.e. we have to strip the same number of bytes of padding
* from the encoded data as we added to the pre-encoded data.
*/
memmove(a, a + padsize, outl - padsize);
outl -= padsize;
}
err:
EVP_ENCODE_CTX_free(ctx);
return outl;
}
/*
* Convert a raw byte string into a null-terminated base64 ASCII string.
* Returns 1 on success or 0 on error.
*/
static int t_tob64(char *dst, const unsigned char *src, int size)
{
EVP_ENCODE_CTX *ctx = EVP_ENCODE_CTX_new();
int outl = 0, outl2 = 0;
unsigned char pad[2] = {0, 0};
size_t leadz = 0;
if (ctx == NULL)
return 0;
EVP_EncodeInit(ctx);
evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_NO_NEWLINES
| EVP_ENCODE_CTX_USE_SRP_ALPHABET);
/*
* We pad at the front with zero bytes until the length is a multiple of 3
* so that EVP_EncodeUpdate/EVP_EncodeFinal does not add any of its own "="
* padding
*/
leadz = 3 - (size % 3);
if (leadz != 3
&& !EVP_EncodeUpdate(ctx, (unsigned char *)dst, &outl, pad,
leadz)) {
EVP_ENCODE_CTX_free(ctx);
return 0;
}
if (!EVP_EncodeUpdate(ctx, (unsigned char *)dst + outl, &outl2, src,
size)) {
EVP_ENCODE_CTX_free(ctx);
return 0;
}
outl += outl2;
EVP_EncodeFinal(ctx, (unsigned char *)dst + outl, &outl2);
outl += outl2;
/* Strip the encoded padding at the front */
if (leadz != 3) {
memmove(dst, dst + leadz, outl - leadz);
dst[outl - leadz] = '\0';
}
EVP_ENCODE_CTX_free(ctx);
return 1;
}
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(void)
{
SRP_user_pwd *ret;
if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
/* SRPerr(SRP_F_SRP_USER_PWD_NEW, ERR_R_MALLOC_FAILURE); */ /*ckerr_ignore*/
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 = OPENSSL_strdup(id)))
return 0;
return (info == NULL || NULL != (vinfo->info = OPENSSL_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 = OPENSSL_malloc(sizeof(*vb));
if (vb == NULL)
return NULL;
if ((vb->users_pwd = sk_SRP_user_pwd_new_null()) == NULL
|| (vb->gN_cache = sk_SRP_gN_cache_new_null()) == 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 = OPENSSL_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;
}
void SRP_VBASE_free(SRP_VBASE *vb)
{
if (!vb)
return;
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);
}
static SRP_gN_cache *SRP_gN_new_init(const char *ch)
{
unsigned char tmp[MAX_LEN];
int len;
SRP_gN_cache *newgN = OPENSSL_malloc(sizeof(*newgN));
if (newgN == NULL)
return NULL;
len = t_fromb64(tmp, sizeof(tmp), ch);
if (len < 0)
goto err;
if ((newgN->b64_bn = OPENSSL_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 = OPENSSL_malloc(sizeof(*gN))) == NULL)
goto err;
if ((gN->id = OPENSSL_strdup(pp[DB_srpid])) == NULL
|| (gN->N = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
== NULL
|| (gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
== NULL
|| 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 .... */
const 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 responsibility */
}
}
}
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);
TXT_DB_free(tmpdb);
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;
}
# if OPENSSL_API_COMPAT < 0x10100000L
/*
* DEPRECATED: use SRP_VBASE_get1_by_user instead.
* 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);
}
# endif
/*
* 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 = NULL;
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_priv_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
goto err;
ctxt = EVP_MD_CTX_new();
if (ctxt == NULL
|| !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))
goto err;
EVP_MD_CTX_free(ctxt);
ctxt = NULL;
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:
EVP_MD_CTX_free(ctxt);
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;
const BIGNUM *N_bn = NULL, *g_bn = NULL;
BIGNUM *N_bn_alloc = NULL, *g_bn_alloc = 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)) <= 0)
goto err;
N_bn_alloc = BN_bin2bn(tmp, len, NULL);
if (N_bn_alloc == NULL)
goto err;
N_bn = N_bn_alloc;
if ((len = t_fromb64(tmp, sizeof(tmp) ,g)) <= 0)
goto err;
g_bn_alloc = BN_bin2bn(tmp, len, NULL);
if (g_bn_alloc == NULL)
goto err;
g_bn = g_bn_alloc;
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)) <= 0)
goto err;
s = BN_bin2bn(tmp2, len, NULL);
}
if (s == NULL)
goto err;
if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))
goto err;
if (BN_bn2bin(v, tmp) < 0)
goto err;
vfsize = BN_num_bytes(v) * 2;
if (((vf = OPENSSL_malloc(vfsize)) == NULL))
goto err;
if (!t_tob64(vf, tmp, BN_num_bytes(v)))
goto err;
if (*salt == NULL) {
char *tmp_salt;
if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
goto err;
}
if (!t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN)) {
OPENSSL_free(tmp_salt);
goto err;
}
*salt = tmp_salt;
}
*verifier = vf;
vf = NULL;
result = defgNid;
err:
BN_free(N_bn_alloc);
BN_free(g_bn_alloc);
OPENSSL_clear_free(vf, vfsize);
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, const BIGNUM *N,
const BIGNUM *g)
{
int result = 0;
BIGNUM *x = NULL;
BN_CTX *bn_ctx = BN_CTX_new();
unsigned char tmp2[MAX_LEN];
BIGNUM *salttmp = NULL, *verif;
if ((user == NULL) ||
(pass == NULL) ||
(salt == NULL) ||
(verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
goto err;
if (*salt == NULL) {
if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
goto err;
salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
if (salttmp == NULL)
goto err;
} else {
salttmp = *salt;
}
x = SRP_Calc_x(salttmp, user, pass);
if (x == NULL)
goto err;
verif = BN_new();
if (verif == NULL)
goto err;
if (!BN_mod_exp(verif, g, x, N, bn_ctx)) {
BN_clear_free(verif);
goto err;
}
result = 1;
*salt = salttmp;
*verifier = verif;
err:
if (salt != NULL && *salt != salttmp)
BN_clear_free(salttmp);
BN_clear_free(x);
BN_CTX_free(bn_ctx);
return result;
}
#endif
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