/* * 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 */ #include #include #include "internal/cryptlib.h" #include "bn_lcl.h" #include #include static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) { unsigned char *buf = NULL; int ret = 0, bit, bytes, mask; time_t tim; if (bits < 0 || (bits == 1 && top > 0)) { BNerr(BN_F_BNRAND, BN_R_BITS_TOO_SMALL); return 0; } if (bits == 0) { BN_zero(rnd); return 1; } bytes = (bits + 7) / 8; bit = (bits - 1) % 8; mask = 0xff << (bit + 1); buf = OPENSSL_malloc(bytes); if (buf == NULL) { BNerr(BN_F_BNRAND, ERR_R_MALLOC_FAILURE); goto err; } /* make a random number and set the top and bottom bits */ time(&tim); RAND_add(&tim, sizeof(tim), 0.0); if (RAND_bytes(buf, bytes) <= 0) goto err; if (pseudorand == 2) { /* * 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(&c, 1) <= 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); } int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(0, rnd, bits, top, bottom); } int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(1, rnd, bits, top, bottom); } int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(2, rnd, bits, top, bottom); } /* random number r: 0 <= r < range */ static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) { int (*bn_rand) (BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; int n; int count = 100; if (range->neg || BN_is_zero(range)) { BNerr(BN_F_BN_RAND_RANGE, 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 (!bn_rand(r, n + 1, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY)) 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) { BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); return 0; } } while (BN_cmp(r, range) >= 0); } else { do { /* range = 11..._2 or range = 101..._2 */ if (!bn_rand(r, n, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY)) return 0; if (!--count) { BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); return 0; } } while (BN_cmp(r, range) >= 0); } bn_check_top(r); return 1; } int BN_rand_range(BIGNUM *r, const BIGNUM *range) { return bn_rand_range(0, r, range); } int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) { return bn_rand_range(1, r, range); } /* * 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) { SHA512_CTX sha; /* * 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; int ret = 0; 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. */ todo = sizeof(priv->d[0]) * priv->top; if (todo > sizeof(private_bytes)) { /* * 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. */ BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE); goto err; } memcpy(private_bytes, priv->d, todo); memset(private_bytes + todo, 0, sizeof(private_bytes) - todo); for (done = 0; done < num_k_bytes;) { if (RAND_bytes(random_bytes, sizeof(random_bytes)) != 1) goto err; SHA512_Init(&sha); SHA512_Update(&sha, &done, sizeof(done)); SHA512_Update(&sha, private_bytes, sizeof(private_bytes)); SHA512_Update(&sha, message, message_len); SHA512_Update(&sha, random_bytes, sizeof(random_bytes)); SHA512_Final(digest, &sha); 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: OPENSSL_free(k_bytes); return ret; }