bn_gf2m.c: optimized BN_GF2m_mod_inv delivers sometimes 2x of ECDSA sign.
[oweals/openssl.git] / crypto / bn / bn_nist.c
index 716dc81825379c258b7e75b88ae44ac3d96d2ce9..4a6c3cc964f754086c95a0e9a34a525106d6df0f 100644 (file)
@@ -73,12 +73,22 @@ static const BN_ULONG _nist_p_192[][BN_NIST_192_TOP] = {
        {0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFFULL},
        {0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFCULL,0xFFFFFFFFFFFFFFFFULL}
        };
+static const BN_ULONG _nist_p_192_sqr[] = {
+       0x0000000000000001ULL,0x0000000000000002ULL,0x0000000000000001ULL,
+       0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFFULL
+       };
 static const BN_ULONG _nist_p_224[][BN_NIST_224_TOP] = {
        {0x0000000000000001ULL,0xFFFFFFFF00000000ULL,
         0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL},
        {0x0000000000000002ULL,0xFFFFFFFE00000000ULL,
         0xFFFFFFFFFFFFFFFFULL,0x00000001FFFFFFFFULL} /* this one is "carry-full" */
        };
+static const BN_ULONG _nist_p_224_sqr[] = {
+       0x0000000000000001ULL,0xFFFFFFFE00000000ULL,
+       0xFFFFFFFFFFFFFFFFULL,0x0000000200000000ULL,
+       0x0000000000000000ULL,0xFFFFFFFFFFFFFFFEULL,
+       0xFFFFFFFFFFFFFFFFULL
+       };
 static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
        {0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL,
         0x0000000000000000ULL,0xFFFFFFFF00000001ULL},
@@ -91,6 +101,12 @@ static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
        {0xFFFFFFFFFFFFFFFBULL,0x00000004FFFFFFFFULL,
         0x0000000000000000ULL,0xFFFFFFFB00000005ULL},
        };
+static const BN_ULONG _nist_p_256_sqr[] = {
+       0x0000000000000001ULL,0xFFFFFFFE00000000ULL,
+       0xFFFFFFFFFFFFFFFFULL,0x00000001FFFFFFFEULL,
+       0x00000001FFFFFFFEULL,0x00000001FFFFFFFEULL,
+       0xFFFFFFFE00000001ULL,0xFFFFFFFE00000002ULL
+       };
 static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
        {0x00000000FFFFFFFFULL,0xFFFFFFFF00000000ULL,0xFFFFFFFFFFFFFFFEULL,
         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
@@ -103,24 +119,48 @@ static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
        {0x00000004FFFFFFFBULL,0xFFFFFFFB00000000ULL,0xFFFFFFFFFFFFFFFAULL,
         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
        };
+static const BN_ULONG _nist_p_384_sqr[] = {
+       0xFFFFFFFE00000001ULL,0x0000000200000000ULL,0xFFFFFFFE00000000ULL,
+       0x0000000200000000ULL,0x0000000000000001ULL,0x0000000000000000ULL,
+       0x00000001FFFFFFFEULL,0xFFFFFFFE00000000ULL,0xFFFFFFFFFFFFFFFDULL,
+       0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL
+       };
 static const BN_ULONG _nist_p_521[] =
        {0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
        0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
        0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
        0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
        0x00000000000001FFULL};
+static const BN_ULONG _nist_p_521_sqr[] = {
+       0x0000000000000001ULL,0x0000000000000000ULL,0x0000000000000000ULL,
+       0x0000000000000000ULL,0x0000000000000000ULL,0x0000000000000000ULL,
+       0x0000000000000000ULL,0x0000000000000000ULL,0xFFFFFFFFFFFFFC00ULL,
+       0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
+       0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
+       0xFFFFFFFFFFFFFFFFULL,0x000000000003FFFFULL
+       };
 #elif BN_BITS2 == 32
 static const BN_ULONG _nist_p_192[][BN_NIST_192_TOP] = {
        {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
        {0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
        {0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFC,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF}
        };
+static const BN_ULONG _nist_p_192_sqr[] = {
+       0x00000001,0x00000000,0x00000002,0x00000000,0x00000001,0x00000000,
+       0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF
+       };
 static const BN_ULONG _nist_p_224[][BN_NIST_224_TOP] = {
        {0x00000001,0x00000000,0x00000000,0xFFFFFFFF,
         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
        {0x00000002,0x00000000,0x00000000,0xFFFFFFFE,
         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF}
        };
+static const BN_ULONG _nist_p_224_sqr[] = {
+       0x00000001,0x00000000,0x00000000,0xFFFFFFFE,
+       0xFFFFFFFF,0xFFFFFFFF,0x00000000,0x00000002,
+       0x00000000,0x00000000,0xFFFFFFFE,0xFFFFFFFF,
+       0xFFFFFFFF,0xFFFFFFFF
+       };
 static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
        {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0x00000000,
         0x00000000,0x00000000,0x00000001,0xFFFFFFFF},
@@ -133,6 +173,12 @@ static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
        {0xFFFFFFFB,0xFFFFFFFF,0xFFFFFFFF,0x00000004,
         0x00000000,0x00000000,0x00000005,0xFFFFFFFB},
        };
+static const BN_ULONG _nist_p_256_sqr[] = {
+       0x00000001,0x00000000,0x00000000,0xFFFFFFFE,
+       0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,0x00000001,
+       0xFFFFFFFE,0x00000001,0xFFFFFFFE,0x00000001,
+       0x00000001,0xFFFFFFFE,0x00000002,0xFFFFFFFE
+       };
 static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
        {0xFFFFFFFF,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,
         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
@@ -145,10 +191,24 @@ static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
        {0xFFFFFFFB,0x00000004,0x00000000,0xFFFFFFFB,0xFFFFFFFA,0xFFFFFFFF,
         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
        };
+static const BN_ULONG _nist_p_384_sqr[] = {
+       0x00000001,0xFFFFFFFE,0x00000000,0x00000002,0x00000000,0xFFFFFFFE,
+       0x00000000,0x00000002,0x00000001,0x00000000,0x00000000,0x00000000,
+       0xFFFFFFFE,0x00000001,0x00000000,0xFFFFFFFE,0xFFFFFFFD,0xFFFFFFFF,
+       0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF
+       };
 static const BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0x000001FF};
+static const BN_ULONG _nist_p_521_sqr[] = {
+       0x00000001,0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,
+       0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,
+       0x00000000,0x00000000,0x00000000,0x00000000,0xFFFFFC00,0xFFFFFFFF,
+       0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
+       0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
+       0xFFFFFFFF,0xFFFFFFFF,0x0003FFFF
+       };
 #else
 #error "unsupported BN_BITS2"
 #endif
@@ -231,7 +291,9 @@ static void nist_cp_bn_0(BN_ULONG *buf, BN_ULONG *a, int top, int max)
        int i;
        BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
 
+#ifdef BN_DEBUG
        OPENSSL_assert(top <= max);
+#endif
        for (i = (top); i != 0; i--)
                *_tmp1++ = *_tmp2++;
        for (i = (max) - (top); i != 0; i--)
@@ -292,12 +354,17 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                 buf[BN_NIST_192_TOP],
                 c_d[BN_NIST_192_TOP],
                *res;
-       size_t   mask;
+       PTR_SIZE_INT mask;
+       static const BIGNUM _bignum_nist_p_192_sqr = {
+               (BN_ULONG *)_nist_p_192_sqr,
+               sizeof(_nist_p_192_sqr)/sizeof(_nist_p_192_sqr[0]),
+               sizeof(_nist_p_192_sqr)/sizeof(_nist_p_192_sqr[0]),
+               0,BN_FLG_STATIC_DATA };
 
        field = &_bignum_nist_p_192; /* just to make sure */
 
-       if (BN_is_negative(a) || a->top > 2*BN_NIST_192_TOP)
-               return BN_nnmod(r, field, a, ctx);
+       if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_192_sqr)>=0)
+               return BN_nnmod(r, a, field, ctx);
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -321,14 +388,14 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        nist_cp_bn_0(buf, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
 
        nist_set_192(t_d, buf, 0, 3, 3);
-       carry = bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
+       carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
        nist_set_192(t_d, buf, 4, 4, 0);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
        nist_set_192(t_d, buf, 5, 5, 5)
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
 
        if (carry > 0)
-               carry = bn_sub_words(r_d,r_d,_nist_p_192[carry-1],BN_NIST_192_TOP);
+               carry = (int)bn_sub_words(r_d,r_d,_nist_p_192[carry-1],BN_NIST_192_TOP);
        else
                carry = 1;
 
@@ -338,9 +405,10 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
         * 'tmp=result-modulus; if (!carry || !borrow) result=tmp;'
         * this is what happens below, but without explicit if:-) a.
         */
-       mask  = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192[0],BN_NIST_192_TOP);
-       mask &= 0-(size_t)carry;
-       res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
+       mask  = 0-(PTR_SIZE_INT)bn_sub_words(c_d,r_d,_nist_p_192[0],BN_NIST_192_TOP);
+       mask &= 0-(PTR_SIZE_INT)carry;
+       res   = (BN_ULONG *)
+        (((PTR_SIZE_INT)c_d&~mask) | ((PTR_SIZE_INT)r_d&mask));
        nist_cp_bn(r_d, res, BN_NIST_192_TOP);
        r->top = BN_NIST_192_TOP;
        bn_correct_top(r);
@@ -371,13 +439,19 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                 buf[BN_NIST_224_TOP],
                 c_d[BN_NIST_224_TOP],
                *res;
-       size_t   mask;
-       union { bn_addsub_f f; size_t p; } u;
+       PTR_SIZE_INT mask;
+       union { bn_addsub_f f; PTR_SIZE_INT p; } u;
+       static const BIGNUM _bignum_nist_p_224_sqr = {
+               (BN_ULONG *)_nist_p_224_sqr,
+               sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
+               sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
+               0,BN_FLG_STATIC_DATA };
+
 
        field = &_bignum_nist_p_224; /* just to make sure */
 
-       if (BN_is_negative(a) || a->top > (2*224+BN_BITS2-1)/BN_BITS2)
-               return BN_nnmod(r, field, a, ctx);
+       if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_224_sqr)>=0)
+               return BN_nnmod(r, a, field, ctx);
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -409,13 +483,13 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
 #endif
        nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
-       carry = bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
+       carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
        nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
        nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
        nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
 
 #if BN_BITS2==64
        carry = (int)(r_d[BN_NIST_224_TOP-1]>>32);
@@ -423,7 +497,7 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        u.f = bn_sub_words;
        if (carry > 0)
                {
-               carry = bn_sub_words(r_d,r_d,_nist_p_224[carry-1],BN_NIST_224_TOP);
+               carry = (int)bn_sub_words(r_d,r_d,_nist_p_224[carry-1],BN_NIST_224_TOP);
 #if BN_BITS2==64
                carry=(int)(~(r_d[BN_NIST_224_TOP-1]>>32))&1;
 #endif
@@ -436,17 +510,19 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                 * the modulus. but if it does, then result has
                 * to be compared to the modulus and conditionally
                 * adjusted by *subtracting* the latter. */
-               carry = bn_add_words(r_d,r_d,_nist_p_224[-carry-1],BN_NIST_224_TOP);
-               mask = 0-(size_t)carry;
-               u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
+               carry = (int)bn_add_words(r_d,r_d,_nist_p_224[-carry-1],BN_NIST_224_TOP);
+               mask = 0-(PTR_SIZE_INT)carry;
+               u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
+                ((PTR_SIZE_INT)bn_add_words&~mask);
                }
        else
                carry = 1;
 
        /* otherwise it's effectively same as in BN_nist_mod_192... */
-       mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_224[0],BN_NIST_224_TOP);
-       mask &= 0-(size_t)carry;
-       res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
+       mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_224[0],BN_NIST_224_TOP);
+       mask &= 0-(PTR_SIZE_INT)carry;
+       res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
+        ((PTR_SIZE_INT)r_d&mask));
        nist_cp_bn(r_d, res, BN_NIST_224_TOP);
        r->top = BN_NIST_224_TOP;
        bn_correct_top(r);
@@ -476,13 +552,18 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                 buf[BN_NIST_256_TOP],
                 c_d[BN_NIST_256_TOP],
                *res;
-       size_t   mask;
-       union { bn_addsub_f f; size_t p; } u;
+       PTR_SIZE_INT mask;
+       union { bn_addsub_f f; PTR_SIZE_INT p; } u;
+       static const BIGNUM _bignum_nist_p_256_sqr = {
+               (BN_ULONG *)_nist_p_256_sqr,
+               sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
+               sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
+               0,BN_FLG_STATIC_DATA };
 
        field = &_bignum_nist_p_256; /* just to make sure */
 
-       if (BN_is_negative(a) || a->top > 2*BN_NIST_256_TOP)
-               return BN_nnmod(r, field, a, ctx);
+       if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_256_sqr)>=0)
+               return BN_nnmod(r, a, field, ctx);
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -509,7 +590,7 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
        /*S2*/
        nist_set_256(c_d, buf, 0, 15, 14, 13, 12, 0, 0, 0);
-       carry = bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
+       carry = (int)bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
        /* left shift */
                {
                register BN_ULONG *ap,t,c;
@@ -524,42 +605,44 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                carry <<= 1;
                carry  |= c;
                }
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*S3*/
        nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*S4*/
        nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*D1*/
        nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*D2*/
        nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*D3*/
        nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
        /*D4*/
        nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 
        /* see BN_nist_mod_224 for explanation */
        u.f = bn_sub_words;
        if (carry > 0)
-               carry = bn_sub_words(r_d,r_d,_nist_p_256[carry-1],BN_NIST_256_TOP);
+               carry = (int)bn_sub_words(r_d,r_d,_nist_p_256[carry-1],BN_NIST_256_TOP);
        else if (carry < 0)
                {
-               carry = bn_add_words(r_d,r_d,_nist_p_256[-carry-1],BN_NIST_256_TOP);
-               mask = 0-(size_t)carry;
-               u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
+               carry = (int)bn_add_words(r_d,r_d,_nist_p_256[-carry-1],BN_NIST_256_TOP);
+               mask = 0-(PTR_SIZE_INT)carry;
+               u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
+                ((PTR_SIZE_INT)bn_add_words&~mask);
                }
        else
                carry = 1;
 
-       mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_256[0],BN_NIST_256_TOP);
-       mask &= 0-(size_t)carry;
-       res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
+       mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_256[0],BN_NIST_256_TOP);
+       mask &= 0-(PTR_SIZE_INT)carry;
+       res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
+        ((PTR_SIZE_INT)r_d&mask));
        nist_cp_bn(r_d, res, BN_NIST_256_TOP);
        r->top = BN_NIST_256_TOP;
        bn_correct_top(r);
@@ -593,13 +676,19 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                 buf[BN_NIST_384_TOP],
                 c_d[BN_NIST_384_TOP],
                *res;
-       size_t   mask;
-       union { bn_addsub_f f; size_t p; } u;
+       PTR_SIZE_INT mask;
+       union { bn_addsub_f f; PTR_SIZE_INT p; } u;
+       static const BIGNUM _bignum_nist_p_384_sqr = {
+               (BN_ULONG *)_nist_p_384_sqr,
+               sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
+               sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
+               0,BN_FLG_STATIC_DATA };
+
 
        field = &_bignum_nist_p_384; /* just to make sure */
 
-       if (BN_is_negative(a) || a->top > 2*BN_NIST_384_TOP)
-               return BN_nnmod(r, field, a, ctx);
+       if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_384_sqr)>=0)
+               return BN_nnmod(r, a, field, ctx);
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -637,48 +726,50 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                        }
                *ap=c;
                }
-       carry = bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
+       carry = (int)bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
                t_d, BN_NIST_256_TOP);
        /*S2 */
-       carry += bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
+       carry += (int)bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
        /*S3*/
        nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*S4*/
        nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*S5*/
        nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*S6*/
        nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
-       carry += bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*D1*/
        nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*D2*/
        nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
        /*D3*/
        nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
-       carry -= bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
+       carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 
        /* see BN_nist_mod_224 for explanation */
        u.f = bn_sub_words;
        if (carry > 0)
-               carry = bn_sub_words(r_d,r_d,_nist_p_384[carry-1],BN_NIST_384_TOP);
+               carry = (int)bn_sub_words(r_d,r_d,_nist_p_384[carry-1],BN_NIST_384_TOP);
        else if (carry < 0)
                {
-               carry = bn_add_words(r_d,r_d,_nist_p_384[-carry-1],BN_NIST_384_TOP);
-               mask = 0-(size_t)carry;
-               u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
+               carry = (int)bn_add_words(r_d,r_d,_nist_p_384[-carry-1],BN_NIST_384_TOP);
+               mask = 0-(PTR_SIZE_INT)carry;
+               u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
+                ((PTR_SIZE_INT)bn_add_words&~mask);
                }
        else
                carry = 1;
 
-       mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_384[0],BN_NIST_384_TOP);
-       mask &= 0-(size_t)carry;
-       res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
+       mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_384[0],BN_NIST_384_TOP);
+       mask &= 0-(PTR_SIZE_INT)carry;
+       res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
+        ((PTR_SIZE_INT)r_d&mask));
        nist_cp_bn(r_d, res, BN_NIST_384_TOP);
        r->top = BN_NIST_384_TOP;
        bn_correct_top(r);
@@ -697,12 +788,17 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        BN_ULONG *r_d, *a_d = a->d,
                 t_d[BN_NIST_521_TOP],
                 val,tmp,*res;
-       size_t  mask;
+       PTR_SIZE_INT mask;
+       static const BIGNUM _bignum_nist_p_521_sqr = {
+               (BN_ULONG *)_nist_p_521_sqr,
+               sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
+               sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
+               0,BN_FLG_STATIC_DATA };
 
        field = &_bignum_nist_p_521; /* just to make sure */
 
-       if (BN_is_negative(a) || BN_num_bits(a)>2*521)
-               return BN_nnmod(r, field, a, ctx);
+       if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_521_sqr)>=0)
+               return BN_nnmod(r, a, field, ctx);
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -737,11 +833,27 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        r_d[i] &= BN_NIST_521_TOP_MASK;
 
        bn_add_words(r_d,r_d,t_d,BN_NIST_521_TOP);
-       mask = 0-(size_t)bn_sub_words(t_d,r_d,_nist_p_521,BN_NIST_521_TOP);
-       res  = (BN_ULONG *)(((size_t)t_d&~mask) | ((size_t)r_d&mask));
+       mask = 0-(PTR_SIZE_INT)bn_sub_words(t_d,r_d,_nist_p_521,BN_NIST_521_TOP);
+       res  = (BN_ULONG *)(((PTR_SIZE_INT)t_d&~mask) |
+        ((PTR_SIZE_INT)r_d&mask));
        nist_cp_bn(r_d,res,BN_NIST_521_TOP);
        r->top = BN_NIST_521_TOP;
        bn_correct_top(r);
 
        return 1;
        }
+
+int (*BN_nist_mod_func(const BIGNUM *p))(BIGNUM *r, const BIGNUM *a, const BIGNUM *field, BN_CTX *ctx)
+       {
+       if (BN_ucmp(&_bignum_nist_p_192, p) == 0)
+               return BN_nist_mod_192;
+       if (BN_ucmp(&_bignum_nist_p_224, p) == 0)
+               return BN_nist_mod_224;
+       if (BN_ucmp(&_bignum_nist_p_256, p) == 0)
+               return BN_nist_mod_256;
+       if (BN_ucmp(&_bignum_nist_p_384, p) == 0)
+               return BN_nist_mod_384;
+       if (BN_ucmp(&_bignum_nist_p_521, p) == 0)
+               return BN_nist_mod_521;
+       return 0;
+       }