/* 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 <string.h> #include <openssl_grpc/err.h> #include <openssl_grpc/mem.h> #include "internal.h" int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { const BIGNUM *tmp; int a_neg = a->neg, ret; // a + b a+b // a + -b a-b // -a + b b-a // -a + -b -(a+b) if (a_neg ^ b->neg) { // only one is negative if (a_neg) { tmp = a; a = b; b = tmp; } // we are now a - b if (BN_ucmp(a, b) < 0) { if (!BN_usub(r, b, a)) { return 0; } r->neg = 1; } else { if (!BN_usub(r, a, b)) { return 0; } r->neg = 0; } return 1; } ret = BN_uadd(r, a, b); r->neg = a_neg; return ret; } int bn_uadd_consttime(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { // Widths are public, so we normalize to make |a| the larger one. if (a->width < b->width) { const BIGNUM *tmp = a; a = b; b = tmp; } int max = a->width; int min = b->width; if (!bn_wexpand(r, max + 1)) { return 0; } r->width = max + 1; BN_ULONG carry = bn_add_words(r->d, a->d, b->d, min); for (int i = min; i < max; i++) { // |r| and |a| may alias, so use a temporary. BN_ULONG tmp = carry + a->d[i]; carry = tmp < a->d[i]; r->d[i] = tmp; } r->d[max] = carry; return 1; } int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { if (!bn_uadd_consttime(r, a, b)) { return 0; } bn_set_minimal_width(r); return 1; } int BN_add_word(BIGNUM *a, BN_ULONG w) { BN_ULONG l; int i; // degenerate case: w is zero if (!w) { return 1; } // degenerate case: a is zero if (BN_is_zero(a)) { return BN_set_word(a, w); } // handle 'a' when negative if (a->neg) { a->neg = 0; i = BN_sub_word(a, w); if (!BN_is_zero(a)) { a->neg = !(a->neg); } return i; } for (i = 0; w != 0 && i < a->width; i++) { a->d[i] = l = a->d[i] + w; w = (w > l) ? 1 : 0; } if (w && i == a->width) { if (!bn_wexpand(a, a->width + 1)) { return 0; } a->width++; a->d[i] = w; } return 1; } int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { int add = 0, neg = 0; const BIGNUM *tmp; // a - b a-b // a - -b a+b // -a - b -(a+b) // -a - -b b-a if (a->neg) { if (b->neg) { tmp = a; a = b; b = tmp; } else { add = 1; neg = 1; } } else { if (b->neg) { add = 1; neg = 0; } } if (add) { if (!BN_uadd(r, a, b)) { return 0; } r->neg = neg; return 1; } if (BN_ucmp(a, b) < 0) { if (!BN_usub(r, b, a)) { return 0; } r->neg = 1; } else { if (!BN_usub(r, a, b)) { return 0; } r->neg = 0; } return 1; } int bn_usub_consttime(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { // |b| may have more words than |a| given non-minimal inputs, but all words // beyond |a->width| must then be zero. int b_width = b->width; if (b_width > a->width) { if (!bn_fits_in_words(b, a->width)) { OPENSSL_PUT_ERROR(BN, BN_R_ARG2_LT_ARG3); return 0; } b_width = a->width; } if (!bn_wexpand(r, a->width)) { return 0; } BN_ULONG borrow = bn_sub_words(r->d, a->d, b->d, b_width); for (int i = b_width; i < a->width; i++) { // |r| and |a| may alias, so use a temporary. BN_ULONG tmp = a->d[i]; r->d[i] = a->d[i] - borrow; borrow = tmp < r->d[i]; } if (borrow) { OPENSSL_PUT_ERROR(BN, BN_R_ARG2_LT_ARG3); return 0; } r->width = a->width; r->neg = 0; return 1; } int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { if (!bn_usub_consttime(r, a, b)) { return 0; } bn_set_minimal_width(r); return 1; } int BN_sub_word(BIGNUM *a, BN_ULONG w) { int i; // degenerate case: w is zero if (!w) { return 1; } // degenerate case: a is zero if (BN_is_zero(a)) { i = BN_set_word(a, w); if (i != 0) { BN_set_negative(a, 1); } return i; } // handle 'a' when negative if (a->neg) { a->neg = 0; i = BN_add_word(a, w); a->neg = 1; return i; } if ((bn_minimal_width(a) == 1) && (a->d[0] < w)) { a->d[0] = w - a->d[0]; a->neg = 1; return 1; } i = 0; for (;;) { if (a->d[i] >= w) { a->d[i] -= w; break; } else { a->d[i] -= w; i++; w = 1; } } if ((a->d[i] == 0) && (i == (a->width - 1))) { a->width--; } return 1; }