/* $OpenBSD: bn_word.c,v 1.20 2023/03/11 14:14:54 jsing Exp $ */ /* 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 #include "bn_local.h" BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) { #ifndef BN_LLONG BN_ULONG ret = 0; #else BN_ULLONG ret = 0; #endif int i; if (w == 0) return (BN_ULONG) - 1; #ifndef BN_ULLONG /* If |w| is too long and we don't have |BN_ULLONG| then we need to fall back * to using |BN_div_word|. */ if (w > ((BN_ULONG)1 << BN_BITS4)) { BIGNUM *tmp = BN_dup(a); if (tmp == NULL) { return (BN_ULONG)-1; } ret = BN_div_word(tmp, w); BN_free(tmp); return ret; } #endif w &= BN_MASK2; for (i = a->top - 1; i >= 0; i--) { #ifndef BN_LLONG ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; #else ret = (BN_ULLONG)(((ret << (BN_ULLONG)BN_BITS2) | a->d[i]) % (BN_ULLONG)w); #endif } return ((BN_ULONG)ret); } BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) { BN_ULONG ret = 0; int i, j; w &= BN_MASK2; if (!w) /* actually this an error (division by zero) */ return (BN_ULONG) - 1; if (a->top == 0) return 0; /* normalize input (so bn_div_words doesn't complain) */ j = BN_BITS2 - BN_num_bits_word(w); w <<= j; if (!BN_lshift(a, a, j)) return (BN_ULONG) - 1; for (i = a->top - 1; i >= 0; i--) { BN_ULONG l, d; l = a->d[i]; bn_div_rem_words(ret, l, w, &d, &ret); a->d[i] = d; } if ((a->top > 0) && (a->d[a->top - 1] == 0)) a->top--; ret >>= j; /* Set negative again, to handle -0 case. */ BN_set_negative(a, a->neg); return (ret); } int BN_add_word(BIGNUM *a, BN_ULONG w) { BN_ULONG l; int i; w &= BN_MASK2; /* 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); BN_set_negative(a, !a->neg); return (i); } for (i = 0; w != 0 && i < a->top; i++) { a->d[i] = l = (a->d[i] + w) & BN_MASK2; w = (w > l) ? 1 : 0; } if (w && i == a->top) { if (!bn_wexpand(a, a->top + 1)) return 0; a->top++; a->d[i] = w; } return (1); } int BN_sub_word(BIGNUM *a, BN_ULONG w) { int i; w &= BN_MASK2; /* 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); BN_set_negative(a, !a->neg); return (i); } if ((a->top == 1) && (a->d[0] < w)) { a->d[0] = w - a->d[0]; BN_set_negative(a, 1); return (1); } i = 0; for (;;) { if (a->d[i] >= w) { a->d[i] -= w; break; } else { a->d[i] = (a->d[i] - w) & BN_MASK2; i++; w = 1; } } if ((a->d[i] == 0) && (i == (a->top - 1))) a->top--; return (1); } int BN_mul_word(BIGNUM *a, BN_ULONG w) { BN_ULONG ll; w &= BN_MASK2; if (a->top) { if (w == 0) BN_zero(a); else { ll = bn_mul_words(a->d, a->d, a->top, w); if (ll) { if (!bn_wexpand(a, a->top + 1)) return (0); a->d[a->top++] = ll; } } } return (1); }