mirror of
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da1c088f59
Reviewed-by: Richard Levitte <levitte@openssl.org> Release: yes
1149 lines
26 KiB
C
1149 lines
26 KiB
C
/*
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* Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <assert.h>
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#include <limits.h>
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#include "internal/cryptlib.h"
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#include "internal/endian.h"
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#include "bn_local.h"
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#include <openssl/opensslconf.h>
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#include "internal/constant_time.h"
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/* This stuff appears to be completely unused, so is deprecated */
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#ifndef OPENSSL_NO_DEPRECATED_0_9_8
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/*-
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* For a 32 bit machine
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* 2 - 4 == 128
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* 3 - 8 == 256
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* 4 - 16 == 512
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* 5 - 32 == 1024
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* 6 - 64 == 2048
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* 7 - 128 == 4096
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* 8 - 256 == 8192
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*/
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static int bn_limit_bits = 0;
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static int bn_limit_num = 8; /* (1<<bn_limit_bits) */
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static int bn_limit_bits_low = 0;
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static int bn_limit_num_low = 8; /* (1<<bn_limit_bits_low) */
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static int bn_limit_bits_high = 0;
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static int bn_limit_num_high = 8; /* (1<<bn_limit_bits_high) */
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static int bn_limit_bits_mont = 0;
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static int bn_limit_num_mont = 8; /* (1<<bn_limit_bits_mont) */
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void BN_set_params(int mult, int high, int low, int mont)
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{
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if (mult >= 0) {
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if (mult > (int)(sizeof(int) * 8) - 1)
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mult = sizeof(int) * 8 - 1;
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bn_limit_bits = mult;
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bn_limit_num = 1 << mult;
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}
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if (high >= 0) {
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if (high > (int)(sizeof(int) * 8) - 1)
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high = sizeof(int) * 8 - 1;
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bn_limit_bits_high = high;
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bn_limit_num_high = 1 << high;
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}
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if (low >= 0) {
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if (low > (int)(sizeof(int) * 8) - 1)
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low = sizeof(int) * 8 - 1;
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bn_limit_bits_low = low;
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bn_limit_num_low = 1 << low;
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}
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if (mont >= 0) {
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if (mont > (int)(sizeof(int) * 8) - 1)
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mont = sizeof(int) * 8 - 1;
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bn_limit_bits_mont = mont;
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bn_limit_num_mont = 1 << mont;
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}
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}
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int BN_get_params(int which)
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{
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if (which == 0)
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return bn_limit_bits;
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else if (which == 1)
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return bn_limit_bits_high;
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else if (which == 2)
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return bn_limit_bits_low;
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else if (which == 3)
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return bn_limit_bits_mont;
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else
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return 0;
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}
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#endif
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const BIGNUM *BN_value_one(void)
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{
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static const BN_ULONG data_one = 1L;
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static const BIGNUM const_one =
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{ (BN_ULONG *)&data_one, 1, 1, 0, BN_FLG_STATIC_DATA };
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return &const_one;
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}
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/*
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* Old Visual Studio ARM compiler miscompiles BN_num_bits_word()
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* https://mta.openssl.org/pipermail/openssl-users/2018-August/008465.html
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*/
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#if defined(_MSC_VER) && defined(_ARM_) && defined(_WIN32_WCE) \
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&& _MSC_VER>=1400 && _MSC_VER<1501
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# define MS_BROKEN_BN_num_bits_word
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# pragma optimize("", off)
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#endif
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int BN_num_bits_word(BN_ULONG l)
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{
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BN_ULONG x, mask;
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int bits = (l != 0);
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#if BN_BITS2 > 32
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x = l >> 32;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 32 & mask;
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l ^= (x ^ l) & mask;
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#endif
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x = l >> 16;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 16 & mask;
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l ^= (x ^ l) & mask;
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x = l >> 8;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 8 & mask;
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l ^= (x ^ l) & mask;
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x = l >> 4;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 4 & mask;
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l ^= (x ^ l) & mask;
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x = l >> 2;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 2 & mask;
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l ^= (x ^ l) & mask;
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x = l >> 1;
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mask = (0 - x) & BN_MASK2;
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mask = (0 - (mask >> (BN_BITS2 - 1)));
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bits += 1 & mask;
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return bits;
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}
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#ifdef MS_BROKEN_BN_num_bits_word
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# pragma optimize("", on)
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#endif
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/*
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* This function still leaks `a->dmax`: it's caller's responsibility to
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* expand the input `a` in advance to a public length.
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*/
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static ossl_inline
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int bn_num_bits_consttime(const BIGNUM *a)
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{
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int j, ret;
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unsigned int mask, past_i;
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int i = a->top - 1;
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bn_check_top(a);
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for (j = 0, past_i = 0, ret = 0; j < a->dmax; j++) {
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mask = constant_time_eq_int(i, j); /* 0xff..ff if i==j, 0x0 otherwise */
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ret += BN_BITS2 & (~mask & ~past_i);
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ret += BN_num_bits_word(a->d[j]) & mask;
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past_i |= mask; /* past_i will become 0xff..ff after i==j */
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}
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/*
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* if BN_is_zero(a) => i is -1 and ret contains garbage, so we mask the
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* final result.
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*/
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mask = ~(constant_time_eq_int(i, ((int)-1)));
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return ret & mask;
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}
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int BN_num_bits(const BIGNUM *a)
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{
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int i = a->top - 1;
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bn_check_top(a);
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if (a->flags & BN_FLG_CONSTTIME) {
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/*
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* We assume that BIGNUMs flagged as CONSTTIME have also been expanded
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* so that a->dmax is not leaking secret information.
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*
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* In other words, it's the caller's responsibility to ensure `a` has
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* been preallocated in advance to a public length if we hit this
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* branch.
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*
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*/
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return bn_num_bits_consttime(a);
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}
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if (BN_is_zero(a))
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return 0;
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return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));
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}
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static void bn_free_d(BIGNUM *a, int clear)
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{
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if (BN_get_flags(a, BN_FLG_SECURE))
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OPENSSL_secure_clear_free(a->d, a->dmax * sizeof(a->d[0]));
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else if (clear != 0)
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OPENSSL_clear_free(a->d, a->dmax * sizeof(a->d[0]));
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else
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OPENSSL_free(a->d);
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}
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void BN_clear_free(BIGNUM *a)
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{
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if (a == NULL)
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return;
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if (a->d != NULL && !BN_get_flags(a, BN_FLG_STATIC_DATA))
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bn_free_d(a, 1);
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if (BN_get_flags(a, BN_FLG_MALLOCED)) {
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OPENSSL_cleanse(a, sizeof(*a));
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OPENSSL_free(a);
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}
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}
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void BN_free(BIGNUM *a)
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{
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if (a == NULL)
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return;
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if (!BN_get_flags(a, BN_FLG_STATIC_DATA))
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bn_free_d(a, 0);
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if (a->flags & BN_FLG_MALLOCED)
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OPENSSL_free(a);
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}
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void bn_init(BIGNUM *a)
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{
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static BIGNUM nilbn;
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*a = nilbn;
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bn_check_top(a);
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}
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BIGNUM *BN_new(void)
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{
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BIGNUM *ret;
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if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL)
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return NULL;
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ret->flags = BN_FLG_MALLOCED;
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bn_check_top(ret);
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return ret;
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}
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BIGNUM *BN_secure_new(void)
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{
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BIGNUM *ret = BN_new();
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if (ret != NULL)
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ret->flags |= BN_FLG_SECURE;
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return ret;
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}
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/* This is used by bn_expand2() */
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/* The caller MUST check that words > b->dmax before calling this */
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static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
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{
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BN_ULONG *a = NULL;
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if (words > (INT_MAX / (4 * BN_BITS2))) {
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ERR_raise(ERR_LIB_BN, BN_R_BIGNUM_TOO_LONG);
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return NULL;
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}
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if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
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ERR_raise(ERR_LIB_BN, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
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return NULL;
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}
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if (BN_get_flags(b, BN_FLG_SECURE))
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a = OPENSSL_secure_zalloc(words * sizeof(*a));
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else
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a = OPENSSL_zalloc(words * sizeof(*a));
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if (a == NULL)
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return NULL;
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assert(b->top <= words);
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if (b->top > 0)
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memcpy(a, b->d, sizeof(*a) * b->top);
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return a;
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}
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/*
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* This is an internal function that should not be used in applications. It
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* ensures that 'b' has enough room for a 'words' word number and initialises
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* any unused part of b->d with leading zeros. It is mostly used by the
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* various BIGNUM routines. If there is an error, NULL is returned. If not,
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* 'b' is returned.
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*/
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BIGNUM *bn_expand2(BIGNUM *b, int words)
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{
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if (words > b->dmax) {
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BN_ULONG *a = bn_expand_internal(b, words);
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if (!a)
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return NULL;
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if (b->d != NULL)
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bn_free_d(b, 1);
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b->d = a;
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b->dmax = words;
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}
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return b;
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}
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BIGNUM *BN_dup(const BIGNUM *a)
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{
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BIGNUM *t;
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if (a == NULL)
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return NULL;
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bn_check_top(a);
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t = BN_get_flags(a, BN_FLG_SECURE) ? BN_secure_new() : BN_new();
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if (t == NULL)
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return NULL;
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if (!BN_copy(t, a)) {
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BN_free(t);
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return NULL;
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}
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bn_check_top(t);
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return t;
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}
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BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
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{
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int bn_words;
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bn_check_top(b);
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bn_words = BN_get_flags(b, BN_FLG_CONSTTIME) ? b->dmax : b->top;
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if (a == b)
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return a;
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if (bn_wexpand(a, bn_words) == NULL)
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return NULL;
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if (b->top > 0)
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memcpy(a->d, b->d, sizeof(b->d[0]) * bn_words);
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a->neg = b->neg;
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a->top = b->top;
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a->flags |= b->flags & BN_FLG_FIXED_TOP;
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bn_check_top(a);
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return a;
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}
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#define FLAGS_DATA(flags) ((flags) & (BN_FLG_STATIC_DATA \
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| BN_FLG_CONSTTIME \
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| BN_FLG_SECURE \
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| BN_FLG_FIXED_TOP))
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#define FLAGS_STRUCT(flags) ((flags) & (BN_FLG_MALLOCED))
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void BN_swap(BIGNUM *a, BIGNUM *b)
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{
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int flags_old_a, flags_old_b;
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BN_ULONG *tmp_d;
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int tmp_top, tmp_dmax, tmp_neg;
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bn_check_top(a);
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bn_check_top(b);
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flags_old_a = a->flags;
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flags_old_b = b->flags;
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tmp_d = a->d;
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tmp_top = a->top;
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tmp_dmax = a->dmax;
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tmp_neg = a->neg;
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a->d = b->d;
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a->top = b->top;
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a->dmax = b->dmax;
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a->neg = b->neg;
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b->d = tmp_d;
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b->top = tmp_top;
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b->dmax = tmp_dmax;
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b->neg = tmp_neg;
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a->flags = FLAGS_STRUCT(flags_old_a) | FLAGS_DATA(flags_old_b);
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b->flags = FLAGS_STRUCT(flags_old_b) | FLAGS_DATA(flags_old_a);
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bn_check_top(a);
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bn_check_top(b);
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}
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void BN_clear(BIGNUM *a)
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{
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if (a == NULL)
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return;
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bn_check_top(a);
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if (a->d != NULL)
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OPENSSL_cleanse(a->d, sizeof(*a->d) * a->dmax);
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a->neg = 0;
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a->top = 0;
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a->flags &= ~BN_FLG_FIXED_TOP;
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}
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BN_ULONG BN_get_word(const BIGNUM *a)
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{
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if (a->top > 1)
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return BN_MASK2;
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else if (a->top == 1)
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return a->d[0];
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/* a->top == 0 */
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return 0;
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}
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int BN_set_word(BIGNUM *a, BN_ULONG w)
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{
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bn_check_top(a);
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if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)
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return 0;
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a->neg = 0;
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a->d[0] = w;
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a->top = (w ? 1 : 0);
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a->flags &= ~BN_FLG_FIXED_TOP;
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bn_check_top(a);
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return 1;
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}
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typedef enum {BIG, LITTLE} endianness_t;
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typedef enum {SIGNED, UNSIGNED} signedness_t;
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static BIGNUM *bin2bn(const unsigned char *s, int len, BIGNUM *ret,
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endianness_t endianness, signedness_t signedness)
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{
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int inc;
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const unsigned char *s2;
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int inc2;
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int neg = 0, xor = 0, carry = 0;
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unsigned int i;
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unsigned int n;
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BIGNUM *bn = NULL;
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/* Negative length is not acceptable */
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if (len < 0)
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return NULL;
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if (ret == NULL)
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ret = bn = BN_new();
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if (ret == NULL)
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return NULL;
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bn_check_top(ret);
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/*
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* If the input has no bits, the number is considered zero.
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* This makes calls with s==NULL and len==0 safe.
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*/
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if (len == 0) {
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BN_clear(ret);
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return ret;
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}
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/*
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* The loop that does the work iterates from least to most
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* significant BIGNUM chunk, so we adapt parameters to transfer
|
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* input bytes accordingly.
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*/
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if (endianness == LITTLE) {
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s2 = s + len - 1;
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inc2 = -1;
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inc = 1;
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} else {
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s2 = s;
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inc2 = 1;
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inc = -1;
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s += len - 1;
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}
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/* Take note of the signedness of the input bytes*/
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if (signedness == SIGNED) {
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neg = !!(*s2 & 0x80);
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xor = neg ? 0xff : 0x00;
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carry = neg;
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}
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|
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/*
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* Skip leading sign extensions (the value of |xor|).
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* This is the only spot where |s2| and |inc2| are used.
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*/
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for ( ; len > 0 && *s2 == xor; s2 += inc2, len--)
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continue;
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|
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/*
|
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* If there was a set of 0xff, we backtrack one byte unless the next
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* one has a sign bit, as the last 0xff is then part of the actual
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* number, rather then a mere sign extension.
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*/
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if (xor == 0xff) {
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if (len == 0 || !(*s2 & 0x80))
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len++;
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}
|
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/* If it was all zeros, we're done */
|
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if (len == 0) {
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ret->top = 0;
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return ret;
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}
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n = ((len - 1) / BN_BYTES) + 1; /* Number of resulting bignum chunks */
|
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if (bn_wexpand(ret, (int)n) == NULL) {
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BN_free(bn);
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return NULL;
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}
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ret->top = n;
|
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ret->neg = neg;
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for (i = 0; n-- > 0; i++) {
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BN_ULONG l = 0; /* Accumulator */
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unsigned int m = 0; /* Offset in a bignum chunk, in bits */
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for (; len > 0 && m < BN_BYTES * 8; len--, s += inc, m += 8) {
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BN_ULONG byte_xored = *s ^ xor;
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BN_ULONG byte = (byte_xored + carry) & 0xff;
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|
|
carry = byte_xored > byte; /* Implicit 1 or 0 */
|
|
l |= (byte << m);
|
|
}
|
|
ret->d[i] = l;
|
|
}
|
|
/*
|
|
* need to call this due to clear byte at top if avoiding having the top
|
|
* bit set (-ve number)
|
|
*/
|
|
bn_correct_top(ret);
|
|
return ret;
|
|
}
|
|
|
|
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
return bin2bn(s, len, ret, BIG, UNSIGNED);
|
|
}
|
|
|
|
BIGNUM *BN_signed_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
return bin2bn(s, len, ret, BIG, SIGNED);
|
|
}
|
|
|
|
static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen,
|
|
endianness_t endianness, signedness_t signedness)
|
|
{
|
|
int inc;
|
|
int n, n8;
|
|
int xor = 0, carry = 0, ext = 0;
|
|
size_t i, lasti, j, atop, mask;
|
|
BN_ULONG l;
|
|
|
|
/*
|
|
* In case |a| is fixed-top, BN_num_bits can return bogus length,
|
|
* but it's assumed that fixed-top inputs ought to be "nominated"
|
|
* even for padded output, so it works out...
|
|
*/
|
|
n8 = BN_num_bits(a);
|
|
n = (n8 + 7) / 8; /* This is what BN_num_bytes() does */
|
|
|
|
/* Take note of the signedness of the bignum */
|
|
if (signedness == SIGNED) {
|
|
xor = a->neg ? 0xff : 0x00;
|
|
carry = a->neg;
|
|
|
|
/*
|
|
* if |n * 8 == n|, then the MSbit is set, otherwise unset.
|
|
* We must compensate with one extra byte if that doesn't
|
|
* correspond to the signedness of the bignum with regards
|
|
* to 2's complement.
|
|
*/
|
|
ext = (n * 8 == n8)
|
|
? !a->neg /* MSbit set on nonnegative bignum */
|
|
: a->neg; /* MSbit unset on negative bignum */
|
|
}
|
|
|
|
if (tolen == -1) {
|
|
tolen = n + ext;
|
|
} else if (tolen < n + ext) { /* uncommon/unlike case */
|
|
BIGNUM temp = *a;
|
|
|
|
bn_correct_top(&temp);
|
|
n8 = BN_num_bits(&temp);
|
|
n = (n8 + 7) / 8; /* This is what BN_num_bytes() does */
|
|
if (tolen < n + ext)
|
|
return -1;
|
|
}
|
|
|
|
/* Swipe through whole available data and don't give away padded zero. */
|
|
atop = a->dmax * BN_BYTES;
|
|
if (atop == 0) {
|
|
if (tolen != 0)
|
|
memset(to, '\0', tolen);
|
|
return tolen;
|
|
}
|
|
|
|
/*
|
|
* The loop that does the work iterates from least significant
|
|
* to most significant BIGNUM limb, so we adapt parameters to
|
|
* transfer output bytes accordingly.
|
|
*/
|
|
if (endianness == LITTLE) {
|
|
inc = 1;
|
|
} else {
|
|
inc = -1;
|
|
to += tolen - 1; /* Move to the last byte, not beyond */
|
|
}
|
|
|
|
lasti = atop - 1;
|
|
atop = a->top * BN_BYTES;
|
|
for (i = 0, j = 0; j < (size_t)tolen; j++) {
|
|
unsigned char byte, byte_xored;
|
|
|
|
l = a->d[i / BN_BYTES];
|
|
mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1));
|
|
byte = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
|
|
byte_xored = byte ^ xor;
|
|
*to = (unsigned char)(byte_xored + carry);
|
|
carry = byte_xored > *to; /* Implicit 1 or 0 */
|
|
to += inc;
|
|
i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */
|
|
}
|
|
|
|
return tolen;
|
|
}
|
|
|
|
int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
if (tolen < 0)
|
|
return -1;
|
|
return bn2binpad(a, to, tolen, BIG, UNSIGNED);
|
|
}
|
|
|
|
int BN_signed_bn2bin(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
if (tolen < 0)
|
|
return -1;
|
|
return bn2binpad(a, to, tolen, BIG, SIGNED);
|
|
}
|
|
|
|
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
|
|
{
|
|
return bn2binpad(a, to, -1, BIG, UNSIGNED);
|
|
}
|
|
|
|
BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
return bin2bn(s, len, ret, LITTLE, UNSIGNED);
|
|
}
|
|
|
|
BIGNUM *BN_signed_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
return bin2bn(s, len, ret, LITTLE, SIGNED);
|
|
}
|
|
|
|
int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
if (tolen < 0)
|
|
return -1;
|
|
return bn2binpad(a, to, tolen, LITTLE, UNSIGNED);
|
|
}
|
|
|
|
int BN_signed_bn2lebin(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
if (tolen < 0)
|
|
return -1;
|
|
return bn2binpad(a, to, tolen, LITTLE, SIGNED);
|
|
}
|
|
|
|
BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
DECLARE_IS_ENDIAN;
|
|
|
|
if (IS_LITTLE_ENDIAN)
|
|
return BN_lebin2bn(s, len, ret);
|
|
return BN_bin2bn(s, len, ret);
|
|
}
|
|
|
|
BIGNUM *BN_signed_native2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
DECLARE_IS_ENDIAN;
|
|
|
|
if (IS_LITTLE_ENDIAN)
|
|
return BN_signed_lebin2bn(s, len, ret);
|
|
return BN_signed_bin2bn(s, len, ret);
|
|
}
|
|
|
|
int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
DECLARE_IS_ENDIAN;
|
|
|
|
if (IS_LITTLE_ENDIAN)
|
|
return BN_bn2lebinpad(a, to, tolen);
|
|
return BN_bn2binpad(a, to, tolen);
|
|
}
|
|
|
|
int BN_signed_bn2native(const BIGNUM *a, unsigned char *to, int tolen)
|
|
{
|
|
DECLARE_IS_ENDIAN;
|
|
|
|
if (IS_LITTLE_ENDIAN)
|
|
return BN_signed_bn2lebin(a, to, tolen);
|
|
return BN_signed_bn2bin(a, to, tolen);
|
|
}
|
|
|
|
int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int i;
|
|
BN_ULONG t1, t2, *ap, *bp;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
i = a->top - b->top;
|
|
if (i != 0)
|
|
return i;
|
|
ap = a->d;
|
|
bp = b->d;
|
|
for (i = a->top - 1; i >= 0; i--) {
|
|
t1 = ap[i];
|
|
t2 = bp[i];
|
|
if (t1 != t2)
|
|
return ((t1 > t2) ? 1 : -1);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int BN_cmp(const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int i;
|
|
int gt, lt;
|
|
BN_ULONG t1, t2;
|
|
|
|
if ((a == NULL) || (b == NULL)) {
|
|
if (a != NULL)
|
|
return -1;
|
|
else if (b != NULL)
|
|
return 1;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
if (a->neg != b->neg) {
|
|
if (a->neg)
|
|
return -1;
|
|
else
|
|
return 1;
|
|
}
|
|
if (a->neg == 0) {
|
|
gt = 1;
|
|
lt = -1;
|
|
} else {
|
|
gt = -1;
|
|
lt = 1;
|
|
}
|
|
|
|
if (a->top > b->top)
|
|
return gt;
|
|
if (a->top < b->top)
|
|
return lt;
|
|
for (i = a->top - 1; i >= 0; i--) {
|
|
t1 = a->d[i];
|
|
t2 = b->d[i];
|
|
if (t1 > t2)
|
|
return gt;
|
|
if (t1 < t2)
|
|
return lt;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int BN_set_bit(BIGNUM *a, int n)
|
|
{
|
|
int i, j, k;
|
|
|
|
if (n < 0)
|
|
return 0;
|
|
|
|
i = n / BN_BITS2;
|
|
j = n % BN_BITS2;
|
|
if (a->top <= i) {
|
|
if (bn_wexpand(a, i + 1) == NULL)
|
|
return 0;
|
|
for (k = a->top; k < i + 1; k++)
|
|
a->d[k] = 0;
|
|
a->top = i + 1;
|
|
a->flags &= ~BN_FLG_FIXED_TOP;
|
|
}
|
|
|
|
a->d[i] |= (((BN_ULONG)1) << j);
|
|
bn_check_top(a);
|
|
return 1;
|
|
}
|
|
|
|
int BN_clear_bit(BIGNUM *a, int n)
|
|
{
|
|
int i, j;
|
|
|
|
bn_check_top(a);
|
|
if (n < 0)
|
|
return 0;
|
|
|
|
i = n / BN_BITS2;
|
|
j = n % BN_BITS2;
|
|
if (a->top <= i)
|
|
return 0;
|
|
|
|
a->d[i] &= (~(((BN_ULONG)1) << j));
|
|
bn_correct_top(a);
|
|
return 1;
|
|
}
|
|
|
|
int BN_is_bit_set(const BIGNUM *a, int n)
|
|
{
|
|
int i, j;
|
|
|
|
bn_check_top(a);
|
|
if (n < 0)
|
|
return 0;
|
|
i = n / BN_BITS2;
|
|
j = n % BN_BITS2;
|
|
if (a->top <= i)
|
|
return 0;
|
|
return (int)(((a->d[i]) >> j) & ((BN_ULONG)1));
|
|
}
|
|
|
|
int BN_mask_bits(BIGNUM *a, int n)
|
|
{
|
|
int b, w;
|
|
|
|
bn_check_top(a);
|
|
if (n < 0)
|
|
return 0;
|
|
|
|
w = n / BN_BITS2;
|
|
b = n % BN_BITS2;
|
|
if (w >= a->top)
|
|
return 0;
|
|
if (b == 0)
|
|
a->top = w;
|
|
else {
|
|
a->top = w + 1;
|
|
a->d[w] &= ~(BN_MASK2 << b);
|
|
}
|
|
bn_correct_top(a);
|
|
return 1;
|
|
}
|
|
|
|
void BN_set_negative(BIGNUM *a, int b)
|
|
{
|
|
if (b && !BN_is_zero(a))
|
|
a->neg = 1;
|
|
else
|
|
a->neg = 0;
|
|
}
|
|
|
|
int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
|
|
{
|
|
int i;
|
|
BN_ULONG aa, bb;
|
|
|
|
if (n == 0)
|
|
return 0;
|
|
|
|
aa = a[n - 1];
|
|
bb = b[n - 1];
|
|
if (aa != bb)
|
|
return ((aa > bb) ? 1 : -1);
|
|
for (i = n - 2; i >= 0; i--) {
|
|
aa = a[i];
|
|
bb = b[i];
|
|
if (aa != bb)
|
|
return ((aa > bb) ? 1 : -1);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Here follows a specialised variants of bn_cmp_words(). It has the
|
|
* capability of performing the operation on arrays of different sizes. The
|
|
* sizes of those arrays is expressed through cl, which is the common length
|
|
* ( basically, min(len(a),len(b)) ), and dl, which is the delta between the
|
|
* two lengths, calculated as len(a)-len(b). All lengths are the number of
|
|
* BN_ULONGs...
|
|
*/
|
|
|
|
int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
|
|
{
|
|
int n, i;
|
|
n = cl - 1;
|
|
|
|
if (dl < 0) {
|
|
for (i = dl; i < 0; i++) {
|
|
if (b[n - i] != 0)
|
|
return -1; /* a < b */
|
|
}
|
|
}
|
|
if (dl > 0) {
|
|
for (i = dl; i > 0; i--) {
|
|
if (a[n + i] != 0)
|
|
return 1; /* a > b */
|
|
}
|
|
}
|
|
return bn_cmp_words(a, b, cl);
|
|
}
|
|
|
|
/*-
|
|
* Constant-time conditional swap of a and b.
|
|
* a and b are swapped if condition is not 0.
|
|
* nwords is the number of words to swap.
|
|
* Assumes that at least nwords are allocated in both a and b.
|
|
* Assumes that no more than nwords are used by either a or b.
|
|
*/
|
|
void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
|
|
{
|
|
BN_ULONG t;
|
|
int i;
|
|
|
|
bn_wcheck_size(a, nwords);
|
|
bn_wcheck_size(b, nwords);
|
|
|
|
condition = ((~condition & ((condition - 1))) >> (BN_BITS2 - 1)) - 1;
|
|
|
|
t = (a->top ^ b->top) & condition;
|
|
a->top ^= t;
|
|
b->top ^= t;
|
|
|
|
t = (a->neg ^ b->neg) & condition;
|
|
a->neg ^= t;
|
|
b->neg ^= t;
|
|
|
|
/*-
|
|
* BN_FLG_STATIC_DATA: indicates that data may not be written to. Intention
|
|
* is actually to treat it as it's read-only data, and some (if not most)
|
|
* of it does reside in read-only segment. In other words observation of
|
|
* BN_FLG_STATIC_DATA in BN_consttime_swap should be treated as fatal
|
|
* condition. It would either cause SEGV or effectively cause data
|
|
* corruption.
|
|
*
|
|
* BN_FLG_MALLOCED: refers to BN structure itself, and hence must be
|
|
* preserved.
|
|
*
|
|
* BN_FLG_SECURE: must be preserved, because it determines how x->d was
|
|
* allocated and hence how to free it.
|
|
*
|
|
* BN_FLG_CONSTTIME: sufficient to mask and swap
|
|
*
|
|
* BN_FLG_FIXED_TOP: indicates that we haven't called bn_correct_top() on
|
|
* the data, so the d array may be padded with additional 0 values (i.e.
|
|
* top could be greater than the minimal value that it could be). We should
|
|
* be swapping it
|
|
*/
|
|
|
|
#define BN_CONSTTIME_SWAP_FLAGS (BN_FLG_CONSTTIME | BN_FLG_FIXED_TOP)
|
|
|
|
t = ((a->flags ^ b->flags) & BN_CONSTTIME_SWAP_FLAGS) & condition;
|
|
a->flags ^= t;
|
|
b->flags ^= t;
|
|
|
|
/* conditionally swap the data */
|
|
for (i = 0; i < nwords; i++) {
|
|
t = (a->d[i] ^ b->d[i]) & condition;
|
|
a->d[i] ^= t;
|
|
b->d[i] ^= t;
|
|
}
|
|
}
|
|
|
|
#undef BN_CONSTTIME_SWAP_FLAGS
|
|
|
|
/* Bits of security, see SP800-57 */
|
|
|
|
int BN_security_bits(int L, int N)
|
|
{
|
|
int secbits, bits;
|
|
if (L >= 15360)
|
|
secbits = 256;
|
|
else if (L >= 7680)
|
|
secbits = 192;
|
|
else if (L >= 3072)
|
|
secbits = 128;
|
|
else if (L >= 2048)
|
|
secbits = 112;
|
|
else if (L >= 1024)
|
|
secbits = 80;
|
|
else
|
|
return 0;
|
|
if (N == -1)
|
|
return secbits;
|
|
bits = N / 2;
|
|
if (bits < 80)
|
|
return 0;
|
|
return bits >= secbits ? secbits : bits;
|
|
}
|
|
|
|
void BN_zero_ex(BIGNUM *a)
|
|
{
|
|
a->neg = 0;
|
|
a->top = 0;
|
|
a->flags &= ~BN_FLG_FIXED_TOP;
|
|
}
|
|
|
|
int BN_abs_is_word(const BIGNUM *a, const BN_ULONG w)
|
|
{
|
|
return ((a->top == 1) && (a->d[0] == w)) || ((w == 0) && (a->top == 0));
|
|
}
|
|
|
|
int BN_is_zero(const BIGNUM *a)
|
|
{
|
|
return a->top == 0;
|
|
}
|
|
|
|
int BN_is_one(const BIGNUM *a)
|
|
{
|
|
return BN_abs_is_word(a, 1) && !a->neg;
|
|
}
|
|
|
|
int BN_is_word(const BIGNUM *a, const BN_ULONG w)
|
|
{
|
|
return BN_abs_is_word(a, w) && (!w || !a->neg);
|
|
}
|
|
|
|
int BN_is_odd(const BIGNUM *a)
|
|
{
|
|
return (a->top > 0) && (a->d[0] & 1);
|
|
}
|
|
|
|
int BN_is_negative(const BIGNUM *a)
|
|
{
|
|
return (a->neg != 0);
|
|
}
|
|
|
|
int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
|
|
BN_CTX *ctx)
|
|
{
|
|
return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx);
|
|
}
|
|
|
|
void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags)
|
|
{
|
|
dest->d = b->d;
|
|
dest->top = b->top;
|
|
dest->dmax = b->dmax;
|
|
dest->neg = b->neg;
|
|
dest->flags = ((dest->flags & BN_FLG_MALLOCED)
|
|
| (b->flags & ~BN_FLG_MALLOCED)
|
|
| BN_FLG_STATIC_DATA | flags);
|
|
}
|
|
|
|
BN_GENCB *BN_GENCB_new(void)
|
|
{
|
|
BN_GENCB *ret;
|
|
|
|
if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL)
|
|
return NULL;
|
|
|
|
return ret;
|
|
}
|
|
|
|
void BN_GENCB_free(BN_GENCB *cb)
|
|
{
|
|
if (cb == NULL)
|
|
return;
|
|
OPENSSL_free(cb);
|
|
}
|
|
|
|
void BN_set_flags(BIGNUM *b, int n)
|
|
{
|
|
b->flags |= n;
|
|
}
|
|
|
|
int BN_get_flags(const BIGNUM *b, int n)
|
|
{
|
|
return b->flags & n;
|
|
}
|
|
|
|
/* Populate a BN_GENCB structure with an "old"-style callback */
|
|
void BN_GENCB_set_old(BN_GENCB *gencb, void (*callback) (int, int, void *),
|
|
void *cb_arg)
|
|
{
|
|
BN_GENCB *tmp_gencb = gencb;
|
|
tmp_gencb->ver = 1;
|
|
tmp_gencb->arg = cb_arg;
|
|
tmp_gencb->cb.cb_1 = callback;
|
|
}
|
|
|
|
/* Populate a BN_GENCB structure with a "new"-style callback */
|
|
void BN_GENCB_set(BN_GENCB *gencb, int (*callback) (int, int, BN_GENCB *),
|
|
void *cb_arg)
|
|
{
|
|
BN_GENCB *tmp_gencb = gencb;
|
|
tmp_gencb->ver = 2;
|
|
tmp_gencb->arg = cb_arg;
|
|
tmp_gencb->cb.cb_2 = callback;
|
|
}
|
|
|
|
void *BN_GENCB_get_arg(BN_GENCB *cb)
|
|
{
|
|
return cb->arg;
|
|
}
|
|
|
|
BIGNUM *bn_wexpand(BIGNUM *a, int words)
|
|
{
|
|
return (words <= a->dmax) ? a : bn_expand2(a, words);
|
|
}
|
|
|
|
void bn_correct_top_consttime(BIGNUM *a)
|
|
{
|
|
int j, atop;
|
|
BN_ULONG limb;
|
|
unsigned int mask;
|
|
|
|
for (j = 0, atop = 0; j < a->dmax; j++) {
|
|
limb = a->d[j];
|
|
limb |= 0 - limb;
|
|
limb >>= BN_BITS2 - 1;
|
|
limb = 0 - limb;
|
|
mask = (unsigned int)limb;
|
|
mask &= constant_time_msb(j - a->top);
|
|
atop = constant_time_select_int(mask, j + 1, atop);
|
|
}
|
|
|
|
mask = constant_time_eq_int(atop, 0);
|
|
a->top = atop;
|
|
a->neg = constant_time_select_int(mask, 0, a->neg);
|
|
a->flags &= ~BN_FLG_FIXED_TOP;
|
|
}
|
|
|
|
void bn_correct_top(BIGNUM *a)
|
|
{
|
|
BN_ULONG *ftl;
|
|
int tmp_top = a->top;
|
|
|
|
if (tmp_top > 0) {
|
|
for (ftl = &(a->d[tmp_top]); tmp_top > 0; tmp_top--) {
|
|
ftl--;
|
|
if (*ftl != 0)
|
|
break;
|
|
}
|
|
a->top = tmp_top;
|
|
}
|
|
if (a->top == 0)
|
|
a->neg = 0;
|
|
a->flags &= ~BN_FLG_FIXED_TOP;
|
|
bn_pollute(a);
|
|
}
|