327 lines
9.2 KiB
C
327 lines
9.2 KiB
C
/*
|
|
* Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
|
|
*
|
|
* Licensed under the Apache License 2.0 (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
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <time.h>
|
|
#include "internal/cryptlib.h"
|
|
#include "crypto/rand.h"
|
|
#include "bn_local.h"
|
|
#include <openssl/rand.h>
|
|
#include <openssl/sha.h>
|
|
#include <openssl/evp.h>
|
|
|
|
typedef enum bnrand_flag_e {
|
|
NORMAL, TESTING, PRIVATE
|
|
} BNRAND_FLAG;
|
|
|
|
static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom,
|
|
unsigned int strength, BN_CTX *ctx)
|
|
{
|
|
unsigned char *buf = NULL;
|
|
int b, ret = 0, bit, bytes, mask;
|
|
OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
|
|
|
|
if (bits == 0) {
|
|
if (top != BN_RAND_TOP_ANY || bottom != BN_RAND_BOTTOM_ANY)
|
|
goto toosmall;
|
|
BN_zero(rnd);
|
|
return 1;
|
|
}
|
|
if (bits < 0 || (bits == 1 && top > 0))
|
|
goto toosmall;
|
|
|
|
bytes = (bits + 7) / 8;
|
|
bit = (bits - 1) % 8;
|
|
mask = 0xff << (bit + 1);
|
|
|
|
buf = OPENSSL_malloc(bytes);
|
|
if (buf == NULL)
|
|
goto err;
|
|
|
|
/* make a random number and set the top and bottom bits */
|
|
b = flag == NORMAL ? RAND_bytes_ex(libctx, buf, bytes, strength)
|
|
: RAND_priv_bytes_ex(libctx, buf, bytes, strength);
|
|
if (b <= 0)
|
|
goto err;
|
|
|
|
if (flag == TESTING) {
|
|
/*
|
|
* generate patterns that are more likely to trigger BN library bugs
|
|
*/
|
|
int i;
|
|
unsigned char c;
|
|
|
|
for (i = 0; i < bytes; i++) {
|
|
if (RAND_bytes_ex(libctx, &c, 1, strength) <= 0)
|
|
goto err;
|
|
if (c >= 128 && i > 0)
|
|
buf[i] = buf[i - 1];
|
|
else if (c < 42)
|
|
buf[i] = 0;
|
|
else if (c < 84)
|
|
buf[i] = 255;
|
|
}
|
|
}
|
|
|
|
if (top >= 0) {
|
|
if (top) {
|
|
if (bit == 0) {
|
|
buf[0] = 1;
|
|
buf[1] |= 0x80;
|
|
} else {
|
|
buf[0] |= (3 << (bit - 1));
|
|
}
|
|
} else {
|
|
buf[0] |= (1 << bit);
|
|
}
|
|
}
|
|
buf[0] &= ~mask;
|
|
if (bottom) /* set bottom bit if requested */
|
|
buf[bytes - 1] |= 1;
|
|
if (!BN_bin2bn(buf, bytes, rnd))
|
|
goto err;
|
|
ret = 1;
|
|
err:
|
|
OPENSSL_clear_free(buf, bytes);
|
|
bn_check_top(rnd);
|
|
return ret;
|
|
|
|
toosmall:
|
|
ERR_raise(ERR_LIB_BN, BN_R_BITS_TOO_SMALL);
|
|
return 0;
|
|
}
|
|
|
|
int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
|
|
unsigned int strength, BN_CTX *ctx)
|
|
{
|
|
return bnrand(NORMAL, rnd, bits, top, bottom, strength, ctx);
|
|
}
|
|
#ifndef FIPS_MODULE
|
|
int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
|
|
{
|
|
return bnrand(NORMAL, rnd, bits, top, bottom, 0, NULL);
|
|
}
|
|
|
|
int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
|
|
{
|
|
return bnrand(TESTING, rnd, bits, top, bottom, 0, NULL);
|
|
}
|
|
#endif
|
|
|
|
int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
|
|
unsigned int strength, BN_CTX *ctx)
|
|
{
|
|
return bnrand(PRIVATE, rnd, bits, top, bottom, strength, ctx);
|
|
}
|
|
|
|
#ifndef FIPS_MODULE
|
|
int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom)
|
|
{
|
|
return bnrand(PRIVATE, rnd, bits, top, bottom, 0, NULL);
|
|
}
|
|
#endif
|
|
|
|
/* random number r: 0 <= r < range */
|
|
static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range,
|
|
unsigned int strength, BN_CTX *ctx)
|
|
{
|
|
int n;
|
|
int count = 100;
|
|
|
|
if (r == NULL) {
|
|
ERR_raise(ERR_LIB_BN, ERR_R_PASSED_NULL_PARAMETER);
|
|
return 0;
|
|
}
|
|
|
|
if (range->neg || BN_is_zero(range)) {
|
|
ERR_raise(ERR_LIB_BN, BN_R_INVALID_RANGE);
|
|
return 0;
|
|
}
|
|
|
|
n = BN_num_bits(range); /* n > 0 */
|
|
|
|
/* BN_is_bit_set(range, n - 1) always holds */
|
|
|
|
if (n == 1)
|
|
BN_zero(r);
|
|
else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) {
|
|
/*
|
|
* range = 100..._2, so 3*range (= 11..._2) is exactly one bit longer
|
|
* than range
|
|
*/
|
|
do {
|
|
if (!bnrand(flag, r, n + 1, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY,
|
|
strength, ctx))
|
|
return 0;
|
|
|
|
/*
|
|
* If r < 3*range, use r := r MOD range (which is either r, r -
|
|
* range, or r - 2*range). Otherwise, iterate once more. Since
|
|
* 3*range = 11..._2, each iteration succeeds with probability >=
|
|
* .75.
|
|
*/
|
|
if (BN_cmp(r, range) >= 0) {
|
|
if (!BN_sub(r, r, range))
|
|
return 0;
|
|
if (BN_cmp(r, range) >= 0)
|
|
if (!BN_sub(r, r, range))
|
|
return 0;
|
|
}
|
|
|
|
if (!--count) {
|
|
ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
|
|
return 0;
|
|
}
|
|
|
|
}
|
|
while (BN_cmp(r, range) >= 0);
|
|
} else {
|
|
do {
|
|
/* range = 11..._2 or range = 101..._2 */
|
|
if (!bnrand(flag, r, n, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY, 0,
|
|
ctx))
|
|
return 0;
|
|
|
|
if (!--count) {
|
|
ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
|
|
return 0;
|
|
}
|
|
}
|
|
while (BN_cmp(r, range) >= 0);
|
|
}
|
|
|
|
bn_check_top(r);
|
|
return 1;
|
|
}
|
|
|
|
int BN_rand_range_ex(BIGNUM *r, const BIGNUM *range, unsigned int strength,
|
|
BN_CTX *ctx)
|
|
{
|
|
return bnrand_range(NORMAL, r, range, strength, ctx);
|
|
}
|
|
|
|
#ifndef FIPS_MODULE
|
|
int BN_rand_range(BIGNUM *r, const BIGNUM *range)
|
|
{
|
|
return bnrand_range(NORMAL, r, range, 0, NULL);
|
|
}
|
|
#endif
|
|
|
|
int BN_priv_rand_range_ex(BIGNUM *r, const BIGNUM *range, unsigned int strength,
|
|
BN_CTX *ctx)
|
|
{
|
|
return bnrand_range(PRIVATE, r, range, strength, ctx);
|
|
}
|
|
|
|
#ifndef FIPS_MODULE
|
|
int BN_priv_rand_range(BIGNUM *r, const BIGNUM *range)
|
|
{
|
|
return bnrand_range(PRIVATE, r, range, 0, NULL);
|
|
}
|
|
|
|
# ifndef OPENSSL_NO_DEPRECATED_3_0
|
|
int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
|
|
{
|
|
return BN_rand(rnd, bits, top, bottom);
|
|
}
|
|
|
|
int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
|
|
{
|
|
return BN_rand_range(r, range);
|
|
}
|
|
# endif
|
|
#endif
|
|
|
|
/*
|
|
* BN_generate_dsa_nonce generates a random number 0 <= out < range. Unlike
|
|
* BN_rand_range, it also includes the contents of |priv| and |message| in
|
|
* the generation so that an RNG failure isn't fatal as long as |priv|
|
|
* remains secret. This is intended for use in DSA and ECDSA where an RNG
|
|
* weakness leads directly to private key exposure unless this function is
|
|
* used.
|
|
*/
|
|
int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range,
|
|
const BIGNUM *priv, const unsigned char *message,
|
|
size_t message_len, BN_CTX *ctx)
|
|
{
|
|
EVP_MD_CTX *mdctx = EVP_MD_CTX_new();
|
|
/*
|
|
* We use 512 bits of random data per iteration to ensure that we have at
|
|
* least |range| bits of randomness.
|
|
*/
|
|
unsigned char random_bytes[64];
|
|
unsigned char digest[SHA512_DIGEST_LENGTH];
|
|
unsigned done, todo;
|
|
/* We generate |range|+8 bytes of random output. */
|
|
const unsigned num_k_bytes = BN_num_bytes(range) + 8;
|
|
unsigned char private_bytes[96];
|
|
unsigned char *k_bytes = NULL;
|
|
int ret = 0;
|
|
EVP_MD *md = NULL;
|
|
OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
|
|
|
|
if (mdctx == NULL)
|
|
goto err;
|
|
|
|
k_bytes = OPENSSL_malloc(num_k_bytes);
|
|
if (k_bytes == NULL)
|
|
goto err;
|
|
|
|
/* We copy |priv| into a local buffer to avoid exposing its length. */
|
|
if (BN_bn2binpad(priv, private_bytes, sizeof(private_bytes)) < 0) {
|
|
/*
|
|
* No reasonable DSA or ECDSA key should have a private key this
|
|
* large and we don't handle this case in order to avoid leaking the
|
|
* length of the private key.
|
|
*/
|
|
ERR_raise(ERR_LIB_BN, BN_R_PRIVATE_KEY_TOO_LARGE);
|
|
goto err;
|
|
}
|
|
|
|
md = EVP_MD_fetch(libctx, "SHA512", NULL);
|
|
if (md == NULL) {
|
|
ERR_raise(ERR_LIB_BN, BN_R_NO_SUITABLE_DIGEST);
|
|
goto err;
|
|
}
|
|
for (done = 0; done < num_k_bytes;) {
|
|
if (RAND_priv_bytes_ex(libctx, random_bytes, sizeof(random_bytes), 0) <= 0)
|
|
goto err;
|
|
|
|
if (!EVP_DigestInit_ex(mdctx, md, NULL)
|
|
|| !EVP_DigestUpdate(mdctx, &done, sizeof(done))
|
|
|| !EVP_DigestUpdate(mdctx, private_bytes,
|
|
sizeof(private_bytes))
|
|
|| !EVP_DigestUpdate(mdctx, message, message_len)
|
|
|| !EVP_DigestUpdate(mdctx, random_bytes, sizeof(random_bytes))
|
|
|| !EVP_DigestFinal_ex(mdctx, digest, NULL))
|
|
goto err;
|
|
|
|
todo = num_k_bytes - done;
|
|
if (todo > SHA512_DIGEST_LENGTH)
|
|
todo = SHA512_DIGEST_LENGTH;
|
|
memcpy(k_bytes + done, digest, todo);
|
|
done += todo;
|
|
}
|
|
|
|
if (!BN_bin2bn(k_bytes, num_k_bytes, out))
|
|
goto err;
|
|
if (BN_mod(out, out, range, ctx) != 1)
|
|
goto err;
|
|
ret = 1;
|
|
|
|
err:
|
|
EVP_MD_CTX_free(mdctx);
|
|
EVP_MD_free(md);
|
|
OPENSSL_clear_free(k_bytes, num_k_bytes);
|
|
OPENSSL_cleanse(digest, sizeof(digest));
|
|
OPENSSL_cleanse(random_bytes, sizeof(random_bytes));
|
|
OPENSSL_cleanse(private_bytes, sizeof(private_bytes));
|
|
return ret;
|
|
}
|