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openssl/crypto/dsa/dsa_gen.c
Matt Caswell 1ff7425d61 Fix a missing NULL check in dsa_builtin_paramgen 
We should check the last BN_CTX_get() call to ensure that it isn't NULL
before we try and use any of the allocated BIGNUMs.

Issue reported by Shi Lei.

Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-09-21 13:32:30 +01:00

599 lines
16 KiB
C
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/*
* Copyright 1995-2016 The OpenSSL Project Authors. 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
*/
/*
* Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
* also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in FIPS PUB
* 180-1)
*/
#define xxxHASH EVP_sha1()
#include <openssl/opensslconf.h>
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/sha.h>
#include "dsa_locl.h"
int DSA_generate_parameters_ex(DSA *ret, int bits,
const unsigned char *seed_in, int seed_len,
int *counter_ret, unsigned long *h_ret,
BN_GENCB *cb)
{
if (ret->meth->dsa_paramgen)
return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
counter_ret, h_ret, cb);
else {
const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1();
size_t qbits = EVP_MD_size(evpmd) * 8;
return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
seed_in, seed_len, NULL, counter_ret,
h_ret, cb);
}
}
int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
const EVP_MD *evpmd, const unsigned char *seed_in,
size_t seed_len, unsigned char *seed_out,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
{
int ok = 0;
unsigned char seed[SHA256_DIGEST_LENGTH];
unsigned char md[SHA256_DIGEST_LENGTH];
unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
BIGNUM *r0, *W, *X, *c, *test;
BIGNUM *g = NULL, *q = NULL, *p = NULL;
BN_MONT_CTX *mont = NULL;
int i, k, n = 0, m = 0, qsize = qbits >> 3;
int counter = 0;
int r = 0;
BN_CTX *ctx = NULL;
unsigned int h = 2;
if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
qsize != SHA256_DIGEST_LENGTH)
/* invalid q size */
return 0;
if (evpmd == NULL)
/* use SHA1 as default */
evpmd = EVP_sha1();
if (bits < 512)
bits = 512;
bits = (bits + 63) / 64 * 64;
if (seed_in != NULL) {
if (seed_len < (size_t)qsize)
return 0;
if (seed_len > (size_t)qsize) {
/* Only consume as much seed as is expected. */
seed_len = qsize;
}
memcpy(seed, seed_in, seed_len);
}
if ((mont = BN_MONT_CTX_new()) == NULL)
goto err;
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
W = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
p = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (test == NULL)
goto err;
if (!BN_lshift(test, BN_value_one(), bits - 1))
goto err;
for (;;) {
for (;;) { /* find q */
int use_random_seed = (seed_in == NULL);
/* step 1 */
if (!BN_GENCB_call(cb, 0, m++))
goto err;
if (use_random_seed) {
if (RAND_bytes(seed, qsize) <= 0)
goto err;
} else {
/* If we come back through, use random seed next time. */
seed_in = NULL;
}
memcpy(buf, seed, qsize);
memcpy(buf2, seed, qsize);
/* precompute "SEED + 1" for step 7: */
for (i = qsize - 1; i >= 0; i--) {
buf[i]++;
if (buf[i] != 0)
break;
}
/* step 2 */
if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
goto err;
if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
goto err;
for (i = 0; i < qsize; i++)
md[i] ^= buf2[i];
/* step 3 */
md[0] |= 0x80;
md[qsize - 1] |= 0x01;
if (!BN_bin2bn(md, qsize, q))
goto err;
/* step 4 */
r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
use_random_seed, cb);
if (r > 0)
break;
if (r != 0)
goto err;
/* do a callback call */
/* step 5 */
}
if (!BN_GENCB_call(cb, 2, 0))
goto err;
if (!BN_GENCB_call(cb, 3, 0))
goto err;
/* step 6 */
counter = 0;
/* "offset = 2" */
n = (bits - 1) / 160;
for (;;) {
if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
goto err;
/* step 7 */
BN_zero(W);
/* now 'buf' contains "SEED + offset - 1" */
for (k = 0; k <= n; k++) {
/*
* obtain "SEED + offset + k" by incrementing:
*/
for (i = qsize - 1; i >= 0; i--) {
buf[i]++;
if (buf[i] != 0)
break;
}
if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL))
goto err;
/* step 8 */
if (!BN_bin2bn(md, qsize, r0))
goto err;
if (!BN_lshift(r0, r0, (qsize << 3) * k))
goto err;
if (!BN_add(W, W, r0))
goto err;
}
/* more of step 8 */
if (!BN_mask_bits(W, bits - 1))
goto err;
if (!BN_copy(X, W))
goto err;
if (!BN_add(X, X, test))
goto err;
/* step 9 */
if (!BN_lshift1(r0, q))
goto err;
if (!BN_mod(c, X, r0, ctx))
goto err;
if (!BN_sub(r0, c, BN_value_one()))
goto err;
if (!BN_sub(p, X, r0))
goto err;
/* step 10 */
if (BN_cmp(p, test) >= 0) {
/* step 11 */
r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
if (r > 0)
goto end; /* found it */
if (r != 0)
goto err;
}
/* step 13 */
counter++;
/* "offset = offset + n + 1" */
/* step 14 */
if (counter >= 4096)
break;
}
}
end:
if (!BN_GENCB_call(cb, 2, 1))
goto err;
/* We now need to generate g */
/* Set r0=(p-1)/q */
if (!BN_sub(test, p, BN_value_one()))
goto err;
if (!BN_div(r0, NULL, test, q, ctx))
goto err;
if (!BN_set_word(test, h))
goto err;
if (!BN_MONT_CTX_set(mont, p, ctx))
goto err;
for (;;) {
/* g=test^r0%p */
if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
goto err;
if (!BN_is_one(g))
break;
if (!BN_add(test, test, BN_value_one()))
goto err;
h++;
}
if (!BN_GENCB_call(cb, 3, 1))
goto err;
ok = 1;
err:
if (ok) {
BN_free(ret->p);
BN_free(ret->q);
BN_free(ret->g);
ret->p = BN_dup(p);
ret->q = BN_dup(q);
ret->g = BN_dup(g);
if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
ok = 0;
goto err;
}
if (counter_ret != NULL)
*counter_ret = counter;
if (h_ret != NULL)
*h_ret = h;
if (seed_out)
memcpy(seed_out, seed, qsize);
}
if (ctx)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
BN_MONT_CTX_free(mont);
return ok;
}
/*
* This is a parameter generation algorithm for the DSA2 algorithm as
* described in FIPS 186-3.
*/
int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
const EVP_MD *evpmd, const unsigned char *seed_in,
size_t seed_len, int idx, unsigned char *seed_out,
int *counter_ret, unsigned long *h_ret,
BN_GENCB *cb)
{
int ok = -1;
unsigned char *seed = NULL, *seed_tmp = NULL;
unsigned char md[EVP_MAX_MD_SIZE];
int mdsize;
BIGNUM *r0, *W, *X, *c, *test;
BIGNUM *g = NULL, *q = NULL, *p = NULL;
BN_MONT_CTX *mont = NULL;
int i, k, n = 0, m = 0, qsize = N >> 3;
int counter = 0;
int r = 0;
BN_CTX *ctx = NULL;
EVP_MD_CTX *mctx = EVP_MD_CTX_new();
unsigned int h = 2;
if (mctx == NULL)
goto err;
if (evpmd == NULL) {
if (N == 160)
evpmd = EVP_sha1();
else if (N == 224)
evpmd = EVP_sha224();
else
evpmd = EVP_sha256();
}
mdsize = EVP_MD_size(evpmd);
/* If unverifiable g generation only don't need seed */
if (!ret->p || !ret->q || idx >= 0) {
if (seed_len == 0)
seed_len = mdsize;
seed = OPENSSL_malloc(seed_len);
if (seed_out)
seed_tmp = seed_out;
else
seed_tmp = OPENSSL_malloc(seed_len);
if (seed == NULL || seed_tmp == NULL)
goto err;
if (seed_in)
memcpy(seed, seed_in, seed_len);
}
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if ((mont = BN_MONT_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
W = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (test == NULL)
goto err;
/* if p, q already supplied generate g only */
if (ret->p && ret->q) {
p = ret->p;
q = ret->q;
if (idx >= 0)
memcpy(seed_tmp, seed, seed_len);
goto g_only;
} else {
p = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
}
if (!BN_lshift(test, BN_value_one(), L - 1))
goto err;
for (;;) {
for (;;) { /* find q */
unsigned char *pmd;
/* step 1 */
if (!BN_GENCB_call(cb, 0, m++))
goto err;
if (!seed_in) {
if (RAND_bytes(seed, seed_len) <= 0)
goto err;
}
/* step 2 */
if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
goto err;
/* Take least significant bits of md */
if (mdsize > qsize)
pmd = md + mdsize - qsize;
else
pmd = md;
if (mdsize < qsize)
memset(md + mdsize, 0, qsize - mdsize);
/* step 3 */
pmd[0] |= 0x80;
pmd[qsize - 1] |= 0x01;
if (!BN_bin2bn(pmd, qsize, q))
goto err;
/* step 4 */
r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
seed_in ? 1 : 0, cb);
if (r > 0)
break;
if (r != 0)
goto err;
/* Provided seed didn't produce a prime: error */
if (seed_in) {
ok = 0;
DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
goto err;
}
/* do a callback call */
/* step 5 */
}
/* Copy seed to seed_out before we mess with it */
if (seed_out)
memcpy(seed_out, seed, seed_len);
if (!BN_GENCB_call(cb, 2, 0))
goto err;
if (!BN_GENCB_call(cb, 3, 0))
goto err;
/* step 6 */
counter = 0;
/* "offset = 1" */
n = (L - 1) / (mdsize << 3);
for (;;) {
if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
goto err;
/* step 7 */
BN_zero(W);
/* now 'buf' contains "SEED + offset - 1" */
for (k = 0; k <= n; k++) {
/*
* obtain "SEED + offset + k" by incrementing:
*/
for (i = seed_len - 1; i >= 0; i--) {
seed[i]++;
if (seed[i] != 0)
break;
}
if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
goto err;
/* step 8 */
if (!BN_bin2bn(md, mdsize, r0))
goto err;
if (!BN_lshift(r0, r0, (mdsize << 3) * k))
goto err;
if (!BN_add(W, W, r0))
goto err;
}
/* more of step 8 */
if (!BN_mask_bits(W, L - 1))
goto err;
if (!BN_copy(X, W))
goto err;
if (!BN_add(X, X, test))
goto err;
/* step 9 */
if (!BN_lshift1(r0, q))
goto err;
if (!BN_mod(c, X, r0, ctx))
goto err;
if (!BN_sub(r0, c, BN_value_one()))
goto err;
if (!BN_sub(p, X, r0))
goto err;
/* step 10 */
if (BN_cmp(p, test) >= 0) {
/* step 11 */
r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
if (r > 0)
goto end; /* found it */
if (r != 0)
goto err;
}
/* step 13 */
counter++;
/* "offset = offset + n + 1" */
/* step 14 */
if (counter >= (int)(4 * L))
break;
}
if (seed_in) {
ok = 0;
DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
goto err;
}
}
end:
if (!BN_GENCB_call(cb, 2, 1))
goto err;
g_only:
/* We now need to generate g */
/* Set r0=(p-1)/q */
if (!BN_sub(test, p, BN_value_one()))
goto err;
if (!BN_div(r0, NULL, test, q, ctx))
goto err;
if (idx < 0) {
if (!BN_set_word(test, h))
goto err;
} else
h = 1;
if (!BN_MONT_CTX_set(mont, p, ctx))
goto err;
for (;;) {
static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e };
if (idx >= 0) {
md[0] = idx & 0xff;
md[1] = (h >> 8) & 0xff;
md[2] = h & 0xff;
if (!EVP_DigestInit_ex(mctx, evpmd, NULL))
goto err;
if (!EVP_DigestUpdate(mctx, seed_tmp, seed_len))
goto err;
if (!EVP_DigestUpdate(mctx, ggen, sizeof(ggen)))
goto err;
if (!EVP_DigestUpdate(mctx, md, 3))
goto err;
if (!EVP_DigestFinal_ex(mctx, md, NULL))
goto err;
if (!BN_bin2bn(md, mdsize, test))
goto err;
}
/* g=test^r0%p */
if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
goto err;
if (!BN_is_one(g))
break;
if (idx < 0 && !BN_add(test, test, BN_value_one()))
goto err;
h++;
if (idx >= 0 && h > 0xffff)
goto err;
}
if (!BN_GENCB_call(cb, 3, 1))
goto err;
ok = 1;
err:
if (ok == 1) {
if (p != ret->p) {
BN_free(ret->p);
ret->p = BN_dup(p);
}
if (q != ret->q) {
BN_free(ret->q);
ret->q = BN_dup(q);
}
BN_free(ret->g);
ret->g = BN_dup(g);
if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
ok = -1;
goto err;
}
if (counter_ret != NULL)
*counter_ret = counter;
if (h_ret != NULL)
*h_ret = h;
}
OPENSSL_free(seed);
if (seed_out != seed_tmp)
OPENSSL_free(seed_tmp);
if (ctx)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
BN_MONT_CTX_free(mont);
EVP_MD_CTX_free(mctx);
return ok;
}
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