/* * 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_add.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" /* r can == a or b */ int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { const BIGNUM *tmp; bn_check_top(a); bn_check_top(b); /* 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); } if (a->neg) /* both are neg */ r->neg=1; else r->neg=0; if (!BN_uadd(r,a,b)) return(0); return(1); } /* unsigned add of b to a, r must be large enough */ int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { register int i; int max,min; BN_ULONG *ap,*bp,*rp,carry,t1; const BIGNUM *tmp; bn_check_top(a); bn_check_top(b); if (a->top < b->top) { tmp=a; a=b; b=tmp; } max=a->top; min=b->top; if (bn_wexpand(r,max+1) == NULL) return(0); r->top=max; ap=a->d; bp=b->d; rp=r->d; carry=0; carry=bn_add_words(rp,ap,bp,min); rp+=min; ap+=min; bp+=min; i=min; if (carry) { while (i < max) { i++; t1= *(ap++); if ((*(rp++)=(t1+1)&BN_MASK2) >= t1) { carry=0; break; } } if ((i >= max) && carry) { *(rp++)=1; r->top++; } } if (rp != ap) { for (; i<max; i++) *(rp++)= *(ap++); } /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/ return(1); } /* unsigned subtraction of b from a, a must be larger than b. */ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { int max,min; register BN_ULONG t1,t2,*ap,*bp,*rp; int i,carry; #if defined(IRIX_CC_BUG) && !defined(LINT) int dummy; #endif bn_check_top(a); bn_check_top(b); if (a->top < b->top) /* hmm... should not be happening */ { BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3); return(0); } max=a->top; min=b->top; if (bn_wexpand(r,max) == NULL) return(0); ap=a->d; bp=b->d; rp=r->d; #if 1 carry=0; for (i=0; i<min; i++) { t1= *(ap++); t2= *(bp++); if (carry) { carry=(t1 <= t2); t1=(t1-t2-1)&BN_MASK2; } else { carry=(t1 < t2); t1=(t1-t2)&BN_MASK2; } #if defined(IRIX_CC_BUG) && !defined(LINT) dummy=t1; #endif *(rp++)=t1&BN_MASK2; } #else carry=bn_sub_words(rp,ap,bp,min); ap+=min; bp+=min; rp+=min; i=min; #endif if (carry) /* subtracted */ { while (i < max) { i++; t1= *(ap++); t2=(t1-1)&BN_MASK2; *(rp++)=t2; if (t1 > t2) break; } } #if 0 memcpy(rp,ap,sizeof(*rp)*(max-i)); #else if (rp != ap) { for (;;) { if (i++ >= max) break; rp[0]=ap[0]; if (i++ >= max) break; rp[1]=ap[1]; if (i++ >= max) break; rp[2]=ap[2]; if (i++ >= max) break; rp[3]=ap[3]; rp+=4; ap+=4; } } #endif r->top=max; bn_fix_top(r); return(1); } int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { int max; int add=0,neg=0; const BIGNUM *tmp; bn_check_top(a); bn_check_top(b); /* 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); } /* We are actually doing a - b :-) */ max=(a->top > b->top)?a->top:b->top; if (bn_wexpand(r,max) == NULL) return(0); 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); }