/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * 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 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 acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS 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 AUTHOR OR 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. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ #include <openssl_grpc/bn.h> #include <openssl_grpc/mem.h> #include <openssl_grpc/type_check.h> #include "internal.h" #include "../../internal.h" static int bn_cmp_words_consttime(const BN_ULONG *a, size_t a_len, const BN_ULONG *b, size_t b_len) { OPENSSL_STATIC_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t), "crypto_word_t is too small"); int ret = 0; // Process the common words in little-endian order. size_t min = a_len < b_len ? a_len : b_len; for (size_t i = 0; i < min; i++) { crypto_word_t eq = constant_time_eq_w(a[i], b[i]); crypto_word_t lt = constant_time_lt_w(a[i], b[i]); ret = constant_time_select_int(eq, ret, constant_time_select_int(lt, -1, 1)); } // If |a| or |b| has non-zero words beyond |min|, they take precedence. if (a_len < b_len) { crypto_word_t mask = 0; for (size_t i = a_len; i < b_len; i++) { mask |= b[i]; } ret = constant_time_select_int(constant_time_is_zero_w(mask), ret, -1); } else if (b_len < a_len) { crypto_word_t mask = 0; for (size_t i = b_len; i < a_len; i++) { mask |= a[i]; } ret = constant_time_select_int(constant_time_is_zero_w(mask), ret, 1); } return ret; } int BN_ucmp(const BIGNUM *a, const BIGNUM *b) { return bn_cmp_words_consttime(a->d, a->width, b->d, b->width); } int BN_cmp(const BIGNUM *a, const BIGNUM *b) { if ((a == NULL) || (b == NULL)) { if (a != NULL) { return -1; } else if (b != NULL) { return 1; } else { return 0; } } // We do not attempt to process the sign bit in constant time. Negative // |BIGNUM|s should never occur in crypto, only calculators. if (a->neg != b->neg) { if (a->neg) { return -1; } return 1; } int ret = BN_ucmp(a, b); return a->neg ? -ret : ret; } int bn_less_than_words(const BN_ULONG *a, const BN_ULONG *b, size_t len) { return bn_cmp_words_consttime(a, len, b, len) < 0; } int BN_abs_is_word(const BIGNUM *bn, BN_ULONG w) { if (bn->width == 0) { return w == 0; } BN_ULONG mask = bn->d[0] ^ w; for (int i = 1; i < bn->width; i++) { mask |= bn->d[i]; } return mask == 0; } int BN_cmp_word(const BIGNUM *a, BN_ULONG b) { BIGNUM b_bn; BN_init(&b_bn); b_bn.d = &b; b_bn.width = b > 0; b_bn.dmax = 1; b_bn.flags = BN_FLG_STATIC_DATA; return BN_cmp(a, &b_bn); } int BN_is_zero(const BIGNUM *bn) { return bn_fits_in_words(bn, 0); } int BN_is_one(const BIGNUM *bn) { return bn->neg == 0 && BN_abs_is_word(bn, 1); } int BN_is_word(const BIGNUM *bn, BN_ULONG w) { return BN_abs_is_word(bn, w) && (w == 0 || bn->neg == 0); } int BN_is_odd(const BIGNUM *bn) { return bn->width > 0 && (bn->d[0] & 1) == 1; } int BN_is_pow2(const BIGNUM *bn) { int width = bn_minimal_width(bn); if (width == 0 || bn->neg) { return 0; } for (int i = 0; i < width - 1; i++) { if (bn->d[i] != 0) { return 0; } } return 0 == (bn->d[width-1] & (bn->d[width-1] - 1)); } int BN_equal_consttime(const BIGNUM *a, const BIGNUM *b) { BN_ULONG mask = 0; // If |a| or |b| has more words than the other, all those words must be zero. for (int i = a->width; i < b->width; i++) { mask |= b->d[i]; } for (int i = b->width; i < a->width; i++) { mask |= a->d[i]; } // Common words must match. int min = a->width < b->width ? a->width : b->width; for (int i = 0; i < min; i++) { mask |= (a->d[i] ^ b->d[i]); } // The sign bit must match. mask |= (a->neg ^ b->neg); return mask == 0; }