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/* crypto/bn/bn_sqr.c */ |
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
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* All rights reserved. |
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* |
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* This package is an SSL implementation written |
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* by Eric Young (eay@cryptsoft.com). |
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* The implementation was written so as to conform with Netscapes SSL. |
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* |
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* This library is free for commercial and non-commercial use as long as |
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* the following conditions are aheared to. The following conditions |
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* apply to all code found in this distribution, be it the RC4, RSA, |
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation |
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* included with this distribution is covered by the same copyright terms |
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* except that the holder is Tim Hudson (tjh@cryptsoft.com). |
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* |
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* Copyright remains Eric Young's, and as such any Copyright notices in |
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* the code are not to be removed. |
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* If this package is used in a product, Eric Young should be given attribution |
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* as the author of the parts of the library used. |
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* This can be in the form of a textual message at program startup or |
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* in documentation (online or textual) provided with the package. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. All advertising materials mentioning features or use of this software |
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* must display the following acknowledgement: |
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* "This product includes cryptographic software written by |
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* Eric Young (eay@cryptsoft.com)" |
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* The word 'cryptographic' can be left out if the rouines from the library |
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* being used are not cryptographic related :-). |
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* 4. If you include any Windows specific code (or a derivative thereof) from |
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* the apps directory (application code) you must include an acknowledgement: |
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
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* |
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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* The licence and distribution terms for any publically available version or |
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* derivative of this code cannot be changed. i.e. this code cannot simply be |
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* copied and put under another distribution licence |
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* [including the GNU Public Licence.] |
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*/ |
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|
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#include <stdio.h> |
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#include "bn_lcl.h" |
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|
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/* r must not be a */ |
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/* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */ |
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int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx) |
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{ |
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int max,al; |
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int ret = 0; |
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BIGNUM *tmp,*rr; |
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|
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#ifdef BN_COUNT |
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printf("BN_sqr %d * %d\n",a->top,a->top); |
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#endif |
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bn_check_top(a); |
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|
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al=a->top; |
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if (al <= 0) |
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{ |
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r->top=0; |
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return(1); |
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} |
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|
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BN_CTX_start(ctx); |
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rr=(a != r) ? r : BN_CTX_get(ctx); |
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tmp=BN_CTX_get(ctx); |
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if (tmp == NULL) goto err; |
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|
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max=(al+al); |
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if (bn_wexpand(rr,max+1) == NULL) goto err; |
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|
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r->neg=0; |
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if (al == 4) |
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{ |
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#ifndef BN_SQR_COMBA |
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BN_ULONG t[8]; |
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bn_sqr_normal(rr->d,a->d,4,t); |
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#else |
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bn_sqr_comba4(rr->d,a->d); |
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#endif |
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} |
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else if (al == 8) |
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{ |
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#ifndef BN_SQR_COMBA |
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BN_ULONG t[16]; |
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bn_sqr_normal(rr->d,a->d,8,t); |
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#else |
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bn_sqr_comba8(rr->d,a->d); |
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#endif |
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} |
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else |
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{ |
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#if defined(BN_RECURSION) |
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if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) |
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{ |
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BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2]; |
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bn_sqr_normal(rr->d,a->d,al,t); |
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} |
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else |
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{ |
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int j,k; |
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|
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j=BN_num_bits_word((BN_ULONG)al); |
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j=1<<(j-1); |
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k=j+j; |
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if (al == j) |
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{ |
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if (bn_wexpand(a,k*2) == NULL) goto err; |
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if (bn_wexpand(tmp,k*2) == NULL) goto err; |
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bn_sqr_recursive(rr->d,a->d,al,tmp->d); |
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} |
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else |
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{ |
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if (bn_wexpand(tmp,max) == NULL) goto err; |
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bn_sqr_normal(rr->d,a->d,al,tmp->d); |
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} |
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} |
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#else |
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if (bn_wexpand(tmp,max) == NULL) goto err; |
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bn_sqr_normal(rr->d,a->d,al,tmp->d); |
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#endif |
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} |
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|
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rr->top=max; |
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if ((max > 0) && (rr->d[max-1] == 0)) rr->top--; |
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if (rr != r) BN_copy(r,rr); |
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ret = 1; |
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err: |
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BN_CTX_end(ctx); |
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return(ret); |
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} |
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|
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/* tmp must have 2*n words */ |
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void bn_sqr_normal(BN_ULONG *r, BN_ULONG *a, int n, BN_ULONG *tmp) |
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{ |
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int i,j,max; |
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BN_ULONG *ap,*rp; |
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|
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max=n*2; |
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ap=a; |
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rp=r; |
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rp[0]=rp[max-1]=0; |
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rp++; |
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j=n; |
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|
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if (--j > 0) |
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{ |
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ap++; |
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rp[j]=bn_mul_words(rp,ap,j,ap[-1]); |
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rp+=2; |
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} |
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|
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for (i=n-2; i>0; i--) |
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{ |
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j--; |
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ap++; |
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rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]); |
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rp+=2; |
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} |
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|
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bn_add_words(r,r,r,max); |
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|
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/* There will not be a carry */ |
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|
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bn_sqr_words(tmp,a,n); |
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|
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bn_add_words(r,r,tmp,max); |
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} |
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|
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#ifdef BN_RECURSION |
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/* r is 2*n words in size, |
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* a and b are both n words in size. (There's not actually a 'b' here ...) |
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* n must be a power of 2. |
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* We multiply and return the result. |
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* t must be 2*n words in size |
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* We calculate |
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* a[0]*b[0] |
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* a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0]) |
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* a[1]*b[1] |
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*/ |
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void bn_sqr_recursive(BN_ULONG *r, BN_ULONG *a, int n2, BN_ULONG *t) |
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{ |
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int n=n2/2; |
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int zero,c1; |
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BN_ULONG ln,lo,*p; |
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|
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#ifdef BN_COUNT |
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printf(" bn_sqr_recursive %d * %d\n",n2,n2); |
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#endif |
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if (n2 == 4) |
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{ |
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#ifndef BN_SQR_COMBA |
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bn_sqr_normal(r,a,4,t); |
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#else |
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bn_sqr_comba4(r,a); |
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#endif |
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return; |
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} |
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else if (n2 == 8) |
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{ |
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#ifndef BN_SQR_COMBA |
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bn_sqr_normal(r,a,8,t); |
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#else |
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bn_sqr_comba8(r,a); |
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#endif |
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return; |
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} |
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if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) |
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{ |
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bn_sqr_normal(r,a,n2,t); |
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return; |
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} |
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/* r=(a[0]-a[1])*(a[1]-a[0]) */ |
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c1=bn_cmp_words(a,&(a[n]),n); |
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zero=0; |
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if (c1 > 0) |
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bn_sub_words(t,a,&(a[n]),n); |
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else if (c1 < 0) |
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bn_sub_words(t,&(a[n]),a,n); |
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else |
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zero=1; |
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|
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/* The result will always be negative unless it is zero */ |
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p= &(t[n2*2]); |
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|
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if (!zero) |
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bn_sqr_recursive(&(t[n2]),t,n,p); |
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else |
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memset(&(t[n2]),0,n2*sizeof(BN_ULONG)); |
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bn_sqr_recursive(r,a,n,p); |
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bn_sqr_recursive(&(r[n2]),&(a[n]),n,p); |
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|
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/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero |
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* r[10] holds (a[0]*b[0]) |
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* r[32] holds (b[1]*b[1]) |
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*/ |
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|
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c1=(int)(bn_add_words(t,r,&(r[n2]),n2)); |
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|
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/* t[32] is negative */ |
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c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2)); |
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|
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/* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1]) |
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* r[10] holds (a[0]*a[0]) |
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* r[32] holds (a[1]*a[1]) |
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* c1 holds the carry bits |
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*/ |
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c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2)); |
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if (c1) |
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{ |
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p= &(r[n+n2]); |
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lo= *p; |
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ln=(lo+c1)&BN_MASK2; |
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*p=ln; |
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|
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/* The overflow will stop before we over write |
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* words we should not overwrite */ |
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if (ln < (BN_ULONG)c1) |
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{ |
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do { |
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p++; |
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lo= *p; |
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ln=(lo+1)&BN_MASK2; |
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*p=ln; |
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} while (ln == 0); |
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} |
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} |
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} |
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#endif |
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