--- /dev/null
+/* crypto/bn/bn_sqr.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 must not be a */
+/* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
+int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
+ {
+ int max,al;
+ int ret = 0;
+ BIGNUM *tmp,*rr;
+
+#ifdef BN_COUNT
+ fprintf(stderr,"BN_sqr %d * %d\n",a->top,a->top);
+#endif
+ bn_check_top(a);
+
+ al=a->top;
+ if (al <= 0)
+ {
+ r->top=0;
+ r->neg = 0;
+ return 1;
+ }
+
+ BN_CTX_start(ctx);
+ rr=(a != r) ? r : BN_CTX_get(ctx);
+ tmp=BN_CTX_get(ctx);
+ if (!rr || !tmp) goto err;
+
+ max = 2 * al; /* Non-zero (from above) */
+ if (bn_wexpand(rr,max) == NULL) goto err;
+
+ if (al == 4)
+ {
+#ifndef BN_SQR_COMBA
+ BN_ULONG t[8];
+ bn_sqr_normal(rr->d,a->d,4,t);
+#else
+ bn_sqr_comba4(rr->d,a->d);
+#endif
+ }
+ else if (al == 8)
+ {
+#ifndef BN_SQR_COMBA
+ BN_ULONG t[16];
+ bn_sqr_normal(rr->d,a->d,8,t);
+#else
+ bn_sqr_comba8(rr->d,a->d);
+#endif
+ }
+ else
+ {
+#if defined(BN_RECURSION)
+ if (al < BN_SQR_RECURSIVE_SIZE_NORMAL)
+ {
+ BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
+ bn_sqr_normal(rr->d,a->d,al,t);
+ }
+ else
+ {
+ int j,k;
+
+ j=BN_num_bits_word((BN_ULONG)al);
+ j=1<<(j-1);
+ k=j+j;
+ if (al == j)
+ {
+ if (bn_wexpand(tmp,k*2) == NULL) goto err;
+ bn_sqr_recursive(rr->d,a->d,al,tmp->d);
+ }
+ else
+ {
+ if (bn_wexpand(tmp,max) == NULL) goto err;
+ bn_sqr_normal(rr->d,a->d,al,tmp->d);
+ }
+ }
+#else
+ if (bn_wexpand(tmp,max) == NULL) goto err;
+ bn_sqr_normal(rr->d,a->d,al,tmp->d);
+#endif
+ }
+
+ rr->neg=0;
+ /* If the most-significant half of the top word of 'a' is zero, then
+ * the square of 'a' will max-1 words. */
+ if(a->d[al - 1] == (a->d[al - 1] & BN_MASK2l))
+ rr->top = max - 1;
+ else
+ rr->top = max;
+ if (rr != r) BN_copy(r,rr);
+ ret = 1;
+ err:
+ bn_check_top(rr);
+ bn_check_top(tmp);
+ BN_CTX_end(ctx);
+ return(ret);
+ }
+
+/* tmp must have 2*n words */
+void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
+ {
+ int i,j,max;
+ const BN_ULONG *ap;
+ BN_ULONG *rp;
+
+ max=n*2;
+ ap=a;
+ rp=r;
+ rp[0]=rp[max-1]=0;
+ rp++;
+ j=n;
+
+ if (--j > 0)
+ {
+ ap++;
+ rp[j]=bn_mul_words(rp,ap,j,ap[-1]);
+ rp+=2;
+ }
+
+ for (i=n-2; i>0; i--)
+ {
+ j--;
+ ap++;
+ rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);
+ rp+=2;
+ }
+
+ bn_add_words(r,r,r,max);
+
+ /* There will not be a carry */
+
+ bn_sqr_words(tmp,a,n);
+
+ bn_add_words(r,r,tmp,max);
+ }
+
+#ifdef BN_RECURSION
+/* r is 2*n words in size,
+ * a and b are both n words in size. (There's not actually a 'b' here ...)
+ * n must be a power of 2.
+ * We multiply and return the result.
+ * t must be 2*n words in size
+ * We calculate
+ * a[0]*b[0]
+ * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
+ * a[1]*b[1]
+ */
+void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
+ {
+ int n=n2/2;
+ int zero,c1;
+ BN_ULONG ln,lo,*p;
+
+#ifdef BN_COUNT
+ fprintf(stderr," bn_sqr_recursive %d * %d\n",n2,n2);
+#endif
+ if (n2 == 4)
+ {
+#ifndef BN_SQR_COMBA
+ bn_sqr_normal(r,a,4,t);
+#else
+ bn_sqr_comba4(r,a);
+#endif
+ return;
+ }
+ else if (n2 == 8)
+ {
+#ifndef BN_SQR_COMBA
+ bn_sqr_normal(r,a,8,t);
+#else
+ bn_sqr_comba8(r,a);
+#endif
+ return;
+ }
+ if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL)
+ {
+ bn_sqr_normal(r,a,n2,t);
+ return;
+ }
+ /* r=(a[0]-a[1])*(a[1]-a[0]) */
+ c1=bn_cmp_words(a,&(a[n]),n);
+ zero=0;
+ if (c1 > 0)
+ bn_sub_words(t,a,&(a[n]),n);
+ else if (c1 < 0)
+ bn_sub_words(t,&(a[n]),a,n);
+ else
+ zero=1;
+
+ /* The result will always be negative unless it is zero */
+ p= &(t[n2*2]);
+
+ if (!zero)
+ bn_sqr_recursive(&(t[n2]),t,n,p);
+ else
+ memset(&(t[n2]),0,n2*sizeof(BN_ULONG));
+ bn_sqr_recursive(r,a,n,p);
+ bn_sqr_recursive(&(r[n2]),&(a[n]),n,p);
+
+ /* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
+ * r[10] holds (a[0]*b[0])
+ * r[32] holds (b[1]*b[1])
+ */
+
+ c1=(int)(bn_add_words(t,r,&(r[n2]),n2));
+
+ /* t[32] is negative */
+ c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
+
+ /* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
+ * r[10] holds (a[0]*a[0])
+ * r[32] holds (a[1]*a[1])
+ * c1 holds the carry bits
+ */
+ c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2));
+ if (c1)
+ {
+ p= &(r[n+n2]);
+ lo= *p;
+ ln=(lo+c1)&BN_MASK2;
+ *p=ln;
+
+ /* The overflow will stop before we over write
+ * words we should not overwrite */
+ if (ln < (BN_ULONG)c1)
+ {
+ do {
+ p++;
+ lo= *p;
+ ln=(lo+1)&BN_MASK2;
+ *p=ln;
+ } while (ln == 0);
+ }
+ }
+ }
+#endif
projects / cassiopeia.git / blobdiff