/* * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved. * * The contents of this file constitute Original Code as defined in and are * subject to the Apple Public Source License Version 1.2 (the 'License'). * You may not use this file except in compliance with the License. Please obtain * a copy of the License at http://www.apple.com/publicsource and read it before * using this file. * * This Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the * specific language governing rights and limitations under the License. */ /* crypto/bn/bn_gcd.c */ /* 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 <stdio.h> #include "cryptlib.h" #include "bn_lcl.h" static BIGNUM *euclid(BIGNUM *a, BIGNUM *b); int BN_gcd(BIGNUM *r, BIGNUM *in_a, BIGNUM *in_b, BN_CTX *ctx) { BIGNUM *a,*b,*t; int ret=0; bn_check_top(in_a); bn_check_top(in_b); BN_CTX_start(ctx); a = BN_CTX_get(ctx); b = BN_CTX_get(ctx); if (a == NULL || b == NULL) goto err; if (BN_copy(a,in_a) == NULL) goto err; if (BN_copy(b,in_b) == NULL) goto err; if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; } t=euclid(a,b); if (t == NULL) goto err; if (BN_copy(r,t) == NULL) goto err; ret=1; err: BN_CTX_end(ctx); return(ret); } static BIGNUM *euclid(BIGNUM *a, BIGNUM *b) { BIGNUM *t; int shifts=0; bn_check_top(a); bn_check_top(b); for (;;) { if (BN_is_zero(b)) break; if (BN_is_odd(a)) { if (BN_is_odd(b)) { if (!BN_sub(a,a,b)) goto err; if (!BN_rshift1(a,a)) goto err; if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; } } else /* a odd - b even */ { if (!BN_rshift1(b,b)) goto err; if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; } } } else /* a is even */ { if (BN_is_odd(b)) { if (!BN_rshift1(a,a)) goto err; if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; } } else /* a even - b even */ { if (!BN_rshift1(a,a)) goto err; if (!BN_rshift1(b,b)) goto err; shifts++; } } } if (shifts) { if (!BN_lshift(a,a,shifts)) goto err; } return(a); err: return(NULL); } /* solves ax == 1 (mod n) */ BIGNUM *BN_mod_inverse(BIGNUM *in, BIGNUM *a, const BIGNUM *n, BN_CTX *ctx) { BIGNUM *A,*B,*X,*Y,*M,*D,*R=NULL; BIGNUM *T,*ret=NULL; int sign; bn_check_top(a); bn_check_top(n); BN_CTX_start(ctx); A = BN_CTX_get(ctx); B = BN_CTX_get(ctx); X = BN_CTX_get(ctx); D = BN_CTX_get(ctx); M = BN_CTX_get(ctx); Y = BN_CTX_get(ctx); if (Y == NULL) goto err; if (in == NULL) R=BN_new(); else R=in; if (R == NULL) goto err; BN_zero(X); BN_one(Y); if (BN_copy(A,a) == NULL) goto err; if (BN_copy(B,n) == NULL) goto err; sign=1; while (!BN_is_zero(B)) { if (!BN_div(D,M,A,B,ctx)) goto err; T=A; A=B; B=M; /* T has a struct, M does not */ if (!BN_mul(T,D,X,ctx)) goto err; if (!BN_add(T,T,Y)) goto err; M=Y; Y=X; X=T; sign= -sign; } if (sign < 0) { if (!BN_sub(Y,n,Y)) goto err; } if (BN_is_one(A)) { if (!BN_mod(R,Y,n,ctx)) goto err; } else { BNerr(BN_F_BN_MOD_INVERSE,BN_R_NO_INVERSE); goto err; } ret=R; err: if ((ret == NULL) && (in == NULL)) BN_free(R); BN_CTX_end(ctx); return(ret); }