1 files changed, 144 insertions, 39 deletions

diff --git a/src/lib/libcrypto/bn/bn_recp.c b/src/lib/libcrypto/bn/bn_recp.c
index 72cd69d3fc..ef5fdd4708 100644
--- a/src/lib/libcrypto/bn/bn_recp.c
+++ b/src/lib/libcrypto/bn/bn_recp.c
@@ -60,66 +60,171 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
-int BN_mod_mul_reciprocal(r, x, y, m, i, nb, ctx)
-BIGNUM *r;
-BIGNUM *x;
-BIGNUM *y;
-BIGNUM *m;
-BIGNUM *i;
-int nb;
-BN_CTX *ctx;
+void BN_RECP_CTX_init(BN_RECP_CTX *recp)
         {
-        int ret=0,j;
-        BIGNUM *a,*b,*c,*d;
+        BN_init(&(recp->N));
+        BN_init(&(recp->Nr));
+        recp->num_bits=0;
+        recp->flags=0;
+        }
+
+BN_RECP_CTX *BN_RECP_CTX_new(void)
+        {
+        BN_RECP_CTX *ret;
+
+        if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
+                return(NULL);
+
+        BN_RECP_CTX_init(ret);
+        ret->flags=BN_FLG_MALLOCED;
+        return(ret);
+        }
+
+void BN_RECP_CTX_free(BN_RECP_CTX *recp)
+        {
+        if(recp == NULL)
+            return;
+
+        BN_free(&(recp->N));
+        BN_free(&(recp->Nr));
+        if (recp->flags & BN_FLG_MALLOCED)
+                OPENSSL_free(recp);
+        }
 
-        a=ctx->bn[ctx->tos++];
-        b=ctx->bn[ctx->tos++];
-        c=ctx->bn[ctx->tos++];
-        d=ctx->bn[ctx->tos++];
+int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
+        {
+        if (!BN_copy(&(recp->N),d)) return 0;
+        if (!BN_zero(&(recp->Nr))) return 0;
+        recp->num_bits=BN_num_bits(d);
+        recp->shift=0;
+        return(1);
+        }
+
+int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
+        BN_RECP_CTX *recp, BN_CTX *ctx)
+        {
+        int ret=0;
+        BIGNUM *a;
+        const BIGNUM *ca;
 
-        if (x == y)
-                { if (!BN_sqr(a,x,ctx)) goto err; }
+        BN_CTX_start(ctx);
+        if ((a = BN_CTX_get(ctx)) == NULL) goto err;
+        if (y != NULL)
+                {
+                if (x == y)
+                        { if (!BN_sqr(a,x,ctx)) goto err; }
+                else
+                        { if (!BN_mul(a,x,y,ctx)) goto err; }
+                ca = a;
+                }
         else
-                { if (!BN_mul(a,x,y)) goto err; }
-        if (!BN_rshift(d,a,nb)) goto err;
-        if (!BN_mul(b,d,i)) goto err;
-        if (!BN_rshift(c,b,nb)) goto err;
-        if (!BN_mul(b,m,c)) goto err;
-        if (!BN_sub(r,a,b)) goto err;
+                ca=x; /* Just do the mod */
+
+        ret = BN_div_recp(NULL,r,ca,recp,ctx);
+err:
+        BN_CTX_end(ctx);
+        return(ret);
+        }
+
+int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
+        BN_RECP_CTX *recp, BN_CTX *ctx)
+        {
+        int i,j,ret=0;
+        BIGNUM *a,*b,*d,*r;
+
+        BN_CTX_start(ctx);
+        a=BN_CTX_get(ctx);
+        b=BN_CTX_get(ctx);
+        if (dv != NULL)
+                d=dv;
+        else
+                d=BN_CTX_get(ctx);
+        if (rem != NULL)
+                r=rem;
+        else
+                r=BN_CTX_get(ctx);
+        if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;
+
+        if (BN_ucmp(m,&(recp->N)) < 0)
+                {
+                if (!BN_zero(d)) return 0;
+                if (!BN_copy(r,m)) return 0;
+                BN_CTX_end(ctx);
+                return(1);
+                }
+
+        /* We want the remainder
+         * Given input of ABCDEF / ab
+         * we need multiply ABCDEF by 3 digests of the reciprocal of ab
+         *
+         */
+
+        /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */
+        i=BN_num_bits(m);
+        j=recp->num_bits<<1;
+        if (j>i) i=j;
+
+        /* Nr := round(2^i / N) */
+        if (i != recp->shift)
+                recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
+                        i,ctx); /* BN_reciprocal returns i, or -1 for an error */
+        if (recp->shift == -1) goto err;
+
+        /* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
+         *    = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
+         *   <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
+         *    = |m/N|
+         */
+        if (!BN_rshift(a,m,recp->num_bits)) goto err;
+        if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
+        if (!BN_rshift(d,b,i-recp->num_bits)) goto err;
+        d->neg=0;
+
+        if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
+        if (!BN_usub(r,m,b)) goto err;
+        r->neg=0;
+
+#if 1
         j=0;
-        while (BN_cmp(r,m) >= 0)
+        while (BN_ucmp(r,&(recp->N)) >= 0)
                 {
                 if (j++ > 2)
                         {
                         BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
                         goto err;
                         }
-                if (!BN_sub(r,r,m)) goto err;
+                if (!BN_usub(r,r,&(recp->N))) goto err;
+                if (!BN_add_word(d,1)) goto err;
                 }
+#endif
 
+        r->neg=BN_is_zero(r)?0:m->neg;
+        d->neg=m->neg^recp->N.neg;
         ret=1;
 err:
-        ctx->tos-=4;
+        BN_CTX_end(ctx);
         return(ret);
-        }
+        } 
 
-int BN_reciprocal(r, m,ctx)
-BIGNUM *r;
-BIGNUM *m;
-BN_CTX *ctx;
+/* len is the expected size of the result
+ * We actually calculate with an extra word of precision, so
+ * we can do faster division if the remainder is not required.
+ */
+/* r := 2^len / m */
+int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
         {
-        int nm,ret= -1;
-        BIGNUM *t;
+        int ret= -1;
+        BIGNUM t;
 
-        t=ctx->bn[ctx->tos++];
+        BN_init(&t);
 
-        nm=BN_num_bits(m);
-        if (!BN_lshift(t,BN_value_one(),nm*2)) goto err;
+        if (!BN_zero(&t)) goto err;
+        if (!BN_set_bit(&t,len)) goto err;
 
-        if (!BN_div(r,NULL,t,m,ctx)) goto err;
-        ret=nm;
+        if (!BN_div(r,NULL,&t,m,ctx)) goto err;
+
+        ret=len;
 err:
-        ctx->tos--;
+        BN_free(&t);
         return(ret);
         }
-