X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fbn%2Fbn_mod.c;h=20f643a13f205203e874e0cd309565c830ffe52e;hp=c351aac14f02b6f02ed0a47dc280e0b6dfe8bbfa;hb=367ace6870e9cbc8fe21dff2ffe4673a98ea42f8;hpb=78414a6a897db42c9bcf06aa21c705811ab33921 diff --git a/crypto/bn/bn_mod.c b/crypto/bn/bn_mod.c index c351aac14f..20f643a13f 100644 --- a/crypto/bn/bn_mod.c +++ b/crypto/bn/bn_mod.c @@ -1,97 +1,321 @@ -/* crypto/bn/bn_mod.c */ -/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) - * All rights reserved. +/* + * Copyright 1998-2018 The OpenSSL Project Authors. 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.] + * 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 -#include "cryptlib.h" +#include "internal/cryptlib.h" #include "bn_lcl.h" -/* rem != m */ -int BN_mod(rem, m, d,ctx) -BIGNUM *rem; -BIGNUM *m; -BIGNUM *d; -BN_CTX *ctx; - { -#if 0 /* The old slow way */ - int i,nm,nd; - BIGNUM *dv; - - if (BN_ucmp(m,d) < 0) - return((BN_copy(rem,m) == NULL)?0:1); - - dv=ctx->bn[ctx->tos]; - - if (!BN_copy(rem,m)) return(0); - - nm=BN_num_bits(rem); - nd=BN_num_bits(d); - if (!BN_lshift(dv,d,nm-nd)) return(0); - for (i=nm-nd; i>=0; i--) - { - if (BN_cmp(rem,dv) >= 0) - { - if (!BN_sub(rem,rem,dv)) return(0); - } - if (!BN_rshift1(dv,dv)) return(0); - } - return(1); -#else - return(BN_div(NULL,rem,m,d,ctx)); -#endif - } +int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) +{ + /* + * like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d| + * always holds) + */ + if (!(BN_mod(r, m, d, ctx))) + return 0; + if (!r->neg) + return 1; + /* now -|d| < r < 0, so we have to set r := r + |d| */ + return (d->neg ? BN_sub : BN_add) (r, r, d); +} + +int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + if (!BN_add(r, a, b)) + return 0; + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_add variant that may be used if both a and b are non-negative and + * less than m. The original algorithm was + * + * if (!BN_uadd(r, a, b)) + * return 0; + * if (BN_ucmp(r, m) >= 0) + * return BN_usub(r, r, m); + * + * which is replaced with addition, subtracting modulus, and conditional + * move depending on whether or not subtraction borrowed. + */ +int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + size_t i, ai, bi, mtop = m->top; + BN_ULONG storage[1024 / BN_BITS2]; + BN_ULONG carry, temp, mask, *rp, *tp = storage; + const BN_ULONG *ap, *bp; + + if (bn_wexpand(r, mtop) == NULL) + return 0; + + if (mtop > sizeof(storage) / sizeof(storage[0]) + && (tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG))) == NULL) + return 0; + + ap = a->d != NULL ? a->d : tp; + bp = b->d != NULL ? b->d : tp; + + for (i = 0, ai = 0, bi = 0, carry = 0; i < mtop;) { + mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1)); + temp = ((ap[ai] & mask) + carry) & BN_MASK2; + carry = (temp < carry); + + mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1)); + tp[i] = ((bp[bi] & mask) + temp) & BN_MASK2; + carry += (tp[i] < temp); + + i++; + ai += (i - a->dmax) >> (8 * sizeof(i) - 1); + bi += (i - b->dmax) >> (8 * sizeof(i) - 1); + } + rp = r->d; + carry -= bn_sub_words(rp, tp, m->d, mtop); + for (i = 0; i < mtop; i++) { + rp[i] = (carry & tp[i]) | (~carry & rp[i]); + ((volatile BN_ULONG *)tp)[i] = 0; + } + r->top = mtop; + r->flags |= BN_FLG_FIXED_TOP; + r->neg = 0; + + if (tp != storage) + OPENSSL_free(tp); + + return 1; +} + +int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + int ret = bn_mod_add_fixed_top(r, a, b, m); + + if (ret) + bn_correct_top(r); + + return ret; +} + +int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + if (!BN_sub(r, a, b)) + return 0; + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_sub variant that may be used if both a and b are non-negative, + * a is less than m, while b is of same bit width as m. It's implemented + * as subtraction followed by two conditional additions. + * + * 0 <= a < m + * 0 <= b < 2^w < 2*m + * + * after subtraction + * + * -2*m < r = a - b < m + * + * Thus it takes up to two conditional additions to make |r| positive. + */ +int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + size_t i, ai, bi, mtop = m->top; + BN_ULONG borrow, carry, ta, tb, mask, *rp; + const BN_ULONG *ap, *bp; + + if (bn_wexpand(r, mtop) == NULL) + return 0; + + rp = r->d; + ap = a->d != NULL ? a->d : rp; + bp = b->d != NULL ? b->d : rp; + + for (i = 0, ai = 0, bi = 0, borrow = 0; i < mtop;) { + mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1)); + ta = ap[ai] & mask; + + mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1)); + tb = bp[bi] & mask; + rp[i] = ta - tb - borrow; + if (ta != tb) + borrow = (ta < tb); + + i++; + ai += (i - a->dmax) >> (8 * sizeof(i) - 1); + bi += (i - b->dmax) >> (8 * sizeof(i) - 1); + } + ap = m->d; + for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) { + ta = ((ap[i] & mask) + carry) & BN_MASK2; + carry = (ta < carry); + rp[i] = (rp[i] + ta) & BN_MASK2; + carry += (rp[i] < ta); + } + borrow -= carry; + for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) { + ta = ((ap[i] & mask) + carry) & BN_MASK2; + carry = (ta < carry); + rp[i] = (rp[i] + ta) & BN_MASK2; + carry += (rp[i] < ta); + } + + r->top = mtop; + r->flags |= BN_FLG_FIXED_TOP; + r->neg = 0; + + return 1; +} + +/* + * BN_mod_sub variant that may be used if both a and b are non-negative and + * less than m + */ +int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + if (!BN_sub(r, a, b)) + return 0; + if (r->neg) + return BN_add(r, r, m); + return 1; +} + +/* slow but works */ +int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + BIGNUM *t; + int ret = 0; + + bn_check_top(a); + bn_check_top(b); + bn_check_top(m); + + BN_CTX_start(ctx); + if ((t = BN_CTX_get(ctx)) == NULL) + goto err; + if (a == b) { + if (!BN_sqr(t, a, ctx)) + goto err; + } else { + if (!BN_mul(t, a, b, ctx)) + goto err; + } + if (!BN_nnmod(r, t, m, ctx)) + goto err; + bn_check_top(r); + ret = 1; + err: + BN_CTX_end(ctx); + return ret; +} + +int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) +{ + if (!BN_sqr(r, a, ctx)) + return 0; + /* r->neg == 0, thus we don't need BN_nnmod */ + return BN_mod(r, r, m, ctx); +} + +int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) +{ + if (!BN_lshift1(r, a)) + return 0; + bn_check_top(r); + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_lshift1 variant that may be used if a is non-negative and less than + * m + */ +int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m) +{ + if (!BN_lshift1(r, a)) + return 0; + bn_check_top(r); + if (BN_cmp(r, m) >= 0) + return BN_sub(r, r, m); + return 1; +} + +int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, + BN_CTX *ctx) +{ + BIGNUM *abs_m = NULL; + int ret; + + if (!BN_nnmod(r, a, m, ctx)) + return 0; + + if (m->neg) { + abs_m = BN_dup(m); + if (abs_m == NULL) + return 0; + abs_m->neg = 0; + } + + ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m)); + bn_check_top(r); + + BN_free(abs_m); + return ret; +} + +/* + * BN_mod_lshift variant that may be used if a is non-negative and less than + * m + */ +int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m) +{ + if (r != a) { + if (BN_copy(r, a) == NULL) + return 0; + } + + while (n > 0) { + int max_shift; + + /* 0 < r < m */ + max_shift = BN_num_bits(m) - BN_num_bits(r); + /* max_shift >= 0 */ + + if (max_shift < 0) { + BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED); + return 0; + } + + if (max_shift > n) + max_shift = n; + + if (max_shift) { + if (!BN_lshift(r, r, max_shift)) + return 0; + n -= max_shift; + } else { + if (!BN_lshift1(r, r)) + return 0; + --n; + } + + /* BN_num_bits(r) <= BN_num_bits(m) */ + + if (BN_cmp(r, m) >= 0) { + if (!BN_sub(r, r, m)) + return 0; + } + } + bn_check_top(r); + + return 1; +}