diff options
Diffstat (limited to 'crypto/bn/bn_sqr.c')
| -rw-r--r-- | crypto/bn/bn_sqr.c | 189 |
1 files changed, 171 insertions, 18 deletions
diff --git a/crypto/bn/bn_sqr.c b/crypto/bn/bn_sqr.c index a8464610e5..19ec0ddf84 100644 --- a/crypto/bn/bn_sqr.c +++ b/crypto/bn/bn_sqr.c @@ -67,30 +67,84 @@ BIGNUM *r; BIGNUM *a; BN_CTX *ctx; { - int i,j,max,al; + int max,al; BIGNUM *tmp; - BN_ULONG *ap,*rp; - tmp=ctx->bn[ctx->tos]; +#ifdef BN_COUNT +printf("BN_sqr %d * %d\n",a->top,a->top); +#endif + bn_check_top(a); + tmp= &(ctx->bn[ctx->tos]); al=a->top; - if (al == 0) + if (al <= 0) { r->top=0; return(1); } - max=(al*2); - if (bn_wexpand(r,1+max) == NULL) return(0); - if (bn_wexpand(tmp,1+max) == NULL) return(0); + max=(al+al); + if (bn_wexpand(r,max+1) == NULL) return(0); r->neg=0; + if (al == 4) + { +#ifndef BN_SQR_COMBA + BN_ULONG t[8]; + bn_sqr_normal(r->d,a->d,4,t); +#else + bn_sqr_comba4(r->d,a->d); +#endif + } + else if (al == 8) + { +#ifndef BN_SQR_COMBA + BN_ULONG t[16]; + bn_sqr_normal(r->d,a->d,8,t); +#else + bn_sqr_comba8(r->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(r->d,a->d,al,t); + } + else + { + if (bn_wexpand(tmp,2*max+1) == NULL) return(0); + bn_sqr_recursive(r->d,a->d,al,tmp->d); + } +#else + if (bn_wexpand(tmp,max) == NULL) return(0); + bn_sqr_normal(r->d,a->d,al,tmp->d); +#endif + } + + r->top=max; + if ((max > 0) && (r->d[max-1] == 0)) r->top--; + return(1); + } + +/* tmp must have 2*n words */ +void bn_sqr_normal(r, a, n, tmp) +BN_ULONG *r; +BN_ULONG *a; +int n; +BN_ULONG *tmp; + { + int i,j,max; + BN_ULONG *ap,*rp; - ap=a->d; - rp=r->d; + max=n*2; + ap=a; + rp=r; rp[0]=rp[max-1]=0; rp++; - j=al; + j=n; if (--j > 0) { @@ -99,7 +153,7 @@ BN_CTX *ctx; rp+=2; } - for (i=2; i<al; i++) + for (i=n-2; i>0; i--) { j--; ap++; @@ -107,16 +161,115 @@ BN_CTX *ctx; rp+=2; } - bn_add_words(r->d,r->d,r->d,max); + bn_add_words(r,r,r,max); /* There will not be a carry */ - bn_sqr_words(tmp->d,a->d,al); + bn_sqr_words(tmp,a,n); - bn_add_words(r->d,r->d,tmp->d,max); - - r->top=max; - if (r->d[max-1] == 0) r->top--; - return(1); + 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. + * n must be a power of 2. + * We multiply and return the result. + * t must be 2*n words in size + * We calulate + * 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(r,a,n2,t) +BN_ULONG *r,*a; +int n2; +BN_ULONG *t; + { + int n=n2/2; + int zero,c1; + BN_ULONG ln,lo,*p; + +#ifdef BN_COUNT +printf(" 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,n*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=bn_add_words(t,r,&(r[n2]),n2); + + /* t[32] is negative */ + c1-=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+=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 |