bn_nist.c update from HEAD.
authorAndy Polyakov <appro@openssl.org>
Fri, 18 Apr 2008 15:54:50 +0000 (15:54 +0000)
committerAndy Polyakov <appro@openssl.org>
Fri, 18 Apr 2008 15:54:50 +0000 (15:54 +0000)
PR: 1593

crypto/bn/bn_nist.c

index fd15c2877727a46c9ead6bd6e41c6c5d5ca09934..e14232fdbb5f11df663f83905876a2d1f54eb7c1 100644 (file)
@@ -99,41 +99,6 @@ static const BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
        0xFFFFFFFF,0x000001FF};
-#elif BN_BITS2 == 16
-static const BN_ULONG _nist_p_192[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFE,
-       0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-static const BN_ULONG _nist_p_224[] = {0x0001,0x0000,0x0000,0x0000,0x0000,
-       0x0000,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-static const BN_ULONG _nist_p_256[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
-       0xFFFF,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0001,0x0000,0xFFFF,
-       0xFFFF};
-static const BN_ULONG _nist_p_384[] = {0xFFFF,0xFFFF,0x0000,0x0000,0x0000,
-       0x0000,0xFFFF,0xFFFF,0xFFFE,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
-       0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-static const BN_ULONG _nist_p_521[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
-       0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
-       0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
-       0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0x01FF};
-#elif BN_BITS2 == 8
-static const BN_ULONG _nist_p_192[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF};
-static const BN_ULONG _nist_p_224[] = {0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
-       0x00,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
-static const BN_ULONG _nist_p_256[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
-       0x00,0x00,0x01,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF};
-static const BN_ULONG _nist_p_384[] = {0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,
-       0x00,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
-static const BN_ULONG _nist_p_521[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-       0xFF,0x01};
 #endif
 
 const BIGNUM *BN_get0_nist_prime_192(void)
@@ -171,17 +136,6 @@ const BIGNUM *BN_get0_nist_prime_521(void)
        return &const_nist_521;
        }
 
-/* some misc internal functions */
-#if BN_BITS2 != 64
-static BN_ULONG _256_data[BN_NIST_256_TOP*6];
-static int _is_set_256_data = 0;
-static void _init_256_data(void);
-
-static BN_ULONG _384_data[BN_NIST_384_TOP*8];
-static int _is_set_384_data = 0;
-static void _init_384_data(void);
-#endif
-
 #define BN_NIST_ADD_ONE(a)     while (!(*(a)=(*(a)+1)&BN_MASK2)) ++(a);
 
 static void nist_cp_bn_0(BN_ULONG *buf, BN_ULONG *a, int top, int max)
@@ -203,10 +157,10 @@ static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
         }
 
 #if BN_BITS2 == 64
-#define bn_cp_64(to, n, from, m)       (to)[n] = (from)[m];
+#define bn_cp_64(to, n, from, m)       (to)[n] = (m>=0)?((from)[m]):0;
 #define bn_64_set_0(to, n)             (to)[n] = (BN_ULONG)0;
 /* TBD */
-#define bn_cp_32(to, n, from, m)       (to)[n] = (from)[m];
+#define bn_cp_32(to, n, from, m)       (to)[n] = (m>=0)?((from)[m]):0;
 #define bn_32_set_0(to, n)             (to)[n] = (BN_ULONG)0;
 #else
 #define bn_cp_64(to, n, from, m) \
@@ -220,26 +174,8 @@ static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
        bn_32_set_0(to, (n)*2+1); \
        }
 #if BN_BITS2 == 32
-#define bn_cp_32(to, n, from, m)       (to)[n] = (from)[m];
+#define bn_cp_32(to, n, from, m)       (to)[n] = (m>=0)?((from)[m]):0;
 #define bn_32_set_0(to, n)             (to)[n] = (BN_ULONG)0;
-#elif BN_BITS2 == 16
-#define bn_cp_32(to, n, from, m) \
-       { \
-       (to)[(n)*2]   = (from)[(m)*2];  \
-       (to)[(n)*2+1] = (from)[(m)*2+1];\
-       }
-#define bn_32_set_0(to, n) { (to)[(n)*2] = 0; (to)[(n)*2+1] = 0; }
-#elif BN_BITS2 == 8
-#define bn_cp_32(to, n, from, m) \
-       { \
-       (to)[(n)*4]   = (from)[(m)*4];  \
-       (to)[(n)*4+1] = (from)[(m)*4+1];\
-       (to)[(n)*4+2] = (from)[(m)*4+2];\
-       (to)[(n)*4+3] = (from)[(m)*4+3];\
-       }
-#define bn_32_set_0(to, n) \
-       { (to)[(n)*4]   = (BN_ULONG)0; (to)[(n)*4+1] = (BN_ULONG)0; \
-         (to)[(n)*4+2] = (BN_ULONG)0; (to)[(n)*4+3] = (BN_ULONG)0; }
 #endif
 #endif /* BN_BITS2 != 64 */
 
@@ -255,9 +191,13 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        BN_CTX *ctx)
        {
        int      top = a->top, i;
+       int      carry;
        register BN_ULONG *r_d, *a_d = a->d;
        BN_ULONG t_d[BN_NIST_192_TOP],
-                buf[BN_NIST_192_TOP];
+                buf[BN_NIST_192_TOP],
+                c_d[BN_NIST_192_TOP],
+               *res;
+       size_t   mask;
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -283,36 +223,28 @@ 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);
 
-#if defined(OPENSSL_SYS_VMS) && defined(__DECC)
-# pragma message save
-# pragma message disable BADSUBSCRIPT
-#endif
-
        nist_set_192(t_d, buf, 0, 3, 3);
-       if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
-               bn_sub_words(r_d, r_d, _nist_p_192, BN_NIST_192_TOP);
-
+       carry = bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+       
        nist_set_192(t_d, buf, 4, 4, 0);
-       if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
-               bn_sub_words(r_d, r_d, _nist_p_192, BN_NIST_192_TOP);
-
-#if defined(OPENSSL_SYS_VMS) && defined(__DECC)
-# pragma message restore
-#endif
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_192_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
        nist_set_192(t_d, buf, 5, 5, 5)
-       if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
-               bn_sub_words(r_d, r_d, _nist_p_192, BN_NIST_192_TOP);
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_192_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
+       nist_cp_bn(r_d, res, BN_NIST_192_TOP);
        r->top = BN_NIST_192_TOP;
        bn_correct_top(r);
-       if (BN_ucmp(r, field) >= 0)
-               {
-               bn_sub_words(r_d, r_d, _nist_p_192, BN_NIST_192_TOP);
-               bn_correct_top(r);
-               }
 
-       bn_check_top(r);
        return 1;
        }
 
@@ -332,9 +264,13 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        {
 #if BN_BITS2 == 32
        int     top = a->top, i;
+       int     carry;
        BN_ULONG *r_d, *a_d = a->d;
        BN_ULONG t_d[BN_NIST_224_TOP],
-                buf[BN_NIST_224_TOP];
+                buf[BN_NIST_224_TOP],
+                c_d[BN_NIST_224_TOP],
+               *res;
+       size_t   mask;
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -361,52 +297,48 @@ 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);
 
        nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
-       if (bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP))
-               bn_sub_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       carry = bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+       
        nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
-       if (bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP))
-               bn_sub_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_224_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
-       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP))
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP);
+       bn_add_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+#else
+       if (bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP))
                bn_add_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+#endif
        nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP);
+       bn_add_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
+       nist_cp_bn(r_d, res, BN_NIST_224_TOP);
+#else
        if (bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP))
                bn_add_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
-
+#endif
        r->top = BN_NIST_224_TOP;
        bn_correct_top(r);
-       if (BN_ucmp(r, field) >= 0)
-               {
-               bn_sub_words(r_d, r_d, _nist_p_224, BN_NIST_224_TOP);
-               bn_correct_top(r);
-               }
-       bn_check_top(r);
+
        return 1;
-#else
+#else  /* BN_BITS!=32 */
        return 0;
 #endif
        }
 
-#if BN_BITS2 == 32
-static void _init_256_data(void)
-       {
-       int     i;
-       BN_ULONG *tmp1 = _256_data;
-       const BN_ULONG *tmp2 = tmp1;
-
-       memcpy(tmp1, _nist_p_256, BN_NIST_256_TOP * sizeof(BN_ULONG));
-       tmp1 += BN_NIST_256_TOP;
-
-       for (i=0; i<5; i++)
-               {
-               bn_add_words(tmp1, _nist_p_256, tmp2, BN_NIST_256_TOP);
-               tmp2  = tmp1;
-               tmp1 += BN_NIST_256_TOP;
-               }
-       _is_set_256_data = 1;
-       }
-#endif
-
 #define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
        { \
        if (a8 != 0) bn_cp_32(to, 0, from, (a8) - 8) else bn_32_set_0(to, 0)\
@@ -427,19 +359,11 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        int     carry = 0;
        register BN_ULONG *a_d = a->d, *r_d;
        BN_ULONG t_d[BN_NIST_256_TOP],
-                t_d2[BN_NIST_256_TOP],
-                buf[BN_NIST_256_TOP];
+                buf[BN_NIST_256_TOP],
+                c_d[BN_NIST_256_TOP],
+               *res;
+       size_t   mask;
 
-       if (!_is_set_256_data)
-               {
-               CRYPTO_w_lock(CRYPTO_LOCK_BN);
-               
-               if (!_is_set_256_data)
-                       _init_256_data();
-               
-               CRYPTO_w_unlock(CRYPTO_LOCK_BN);
-               }
-       
        i = BN_ucmp(field, a);
        if (i == 0)
                {
@@ -467,86 +391,91 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        /*S1*/
        nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
        /*S2*/
-       nist_set_256(t_d2,buf, 0, 15, 14, 13, 12, 0, 0, 0);
-       carry = bn_add_words(t_d, t_d, t_d2, BN_NIST_256_TOP);
-       /* left shift */
-               {
-               register BN_ULONG *ap,t,c;
-               ap = t_d;
-               c=0;
-               for (i = BN_NIST_256_TOP; i != 0; --i)
-                       {
-                       t= *ap;
-                       *(ap++)=((t<<1)|c)&BN_MASK2;
-                       c=(t & BN_TBIT)?1:0;
-                       }
-               carry <<= 1;
-               carry  |= c;
-               }
+       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);
+       mask = 0-(size_t)bn_sub_words(c_d,t_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)t_d&~mask));
+
+       carry = bn_add_words(t_d, res, res, BN_NIST_256_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,t_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)t_d&~mask));
+
+       carry = bn_add_words(r_d, r_d, res, BN_NIST_256_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
-       carry += 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 = bn_add_words(r_d, res, t_d, BN_NIST_256_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*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);
-
-       if (carry)
-               bn_sub_words(r_d, r_d, _256_data + BN_NIST_256_TOP *
-                               (carry-1), BN_NIST_256_TOP);
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_256_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
        /*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);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
+       bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));   
+#else
+       if (bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP))
+               bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+#endif
        /*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);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
+       bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));   
+#else
+       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
+               bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+#endif
        /*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);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
+       bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));   
+#else
+       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
+               bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+#endif
        /*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);
-       
-       if (carry)
-               bn_add_words(r_d, r_d, _256_data + BN_NIST_256_TOP *
-                               (carry-1), BN_NIST_256_TOP);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
+       bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));   
 
+       nist_cp_bn(r_d, res, BN_NIST_384_TOP);
+#else
+       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
+               bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
+#endif
        r->top = BN_NIST_256_TOP;
        bn_correct_top(r);
-       if (BN_ucmp(r, field) >= 0)
-               {
-               bn_sub_words(r_d, r_d, _nist_p_256, BN_NIST_256_TOP);
-               bn_correct_top(r);
-               }
-       bn_check_top(r);
+
        return 1;
-#else
+#else  /* BN_BITS!=32 */
        return 0;
 #endif
        }
 
-#if BN_BITS2 == 32
-static void _init_384_data(void)
-       {
-       int     i;
-       BN_ULONG *tmp1 = _384_data;
-       const BN_ULONG *tmp2 = tmp1;
-
-       memcpy(tmp1, _nist_p_384, BN_NIST_384_TOP * sizeof(BN_ULONG));
-       tmp1 += BN_NIST_384_TOP;
-
-       for (i=0; i<7; i++)
-               {
-               bn_add_words(tmp1, _nist_p_384, tmp2, BN_NIST_384_TOP);
-               tmp2  = tmp1;
-               tmp1 += BN_NIST_384_TOP;
-               }
-       _is_set_384_data = 1;
-       }
-#endif
-
 #define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
        { \
        if (a12 != 0) bn_cp_32(to, 0, from,  (a12) - 12) else bn_32_set_0(to, 0)\
@@ -571,17 +500,10 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
        int     carry = 0;
        register BN_ULONG *r_d, *a_d = a->d;
        BN_ULONG t_d[BN_NIST_384_TOP],
-                buf[BN_NIST_384_TOP];
-
-       if (!_is_set_384_data)
-               {
-               CRYPTO_w_lock(CRYPTO_LOCK_BN);
-               
-               if (!_is_set_384_data)
-                       _init_384_data();
-
-               CRYPTO_w_unlock(CRYPTO_LOCK_BN);
-               }
+                buf[BN_NIST_384_TOP],
+                c_d[BN_NIST_384_TOP],
+               *res;
+       size_t   mask;
 
        i = BN_ucmp(field, a);
        if (i == 0)
@@ -624,50 +546,93 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
                }
        carry = bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
                t_d, BN_NIST_256_TOP);
+       /*
+        * we need if (result>=modulus) subtract(result,modulus);
+        * in n-bit space this can be expressed as
+        * if (carry || result>=modulus) subtract(result,modulus);
+        * the catch is that comparison implies subtraction and
+        * therefore one can write tmp=subtract(result,modulus);
+        * and then if(carry || !borrow) result=tmp; this's what
+        * happens below, but without explicit if:-) a.
+        */
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*S2 */
-       carry += bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
+       carry = bn_add_words(r_d, res, buf, BN_NIST_384_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*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 = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*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 = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*S5*/
-       nist_set_256(t_d, buf, 0, 0, 0, 0, 23-4, 22-4, 21-4, 20-4);
-       carry += bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
-               t_d, BN_NIST_256_TOP);
+       nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+
        /*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);
-
-       if (carry)
-               bn_sub_words(r_d, r_d, _384_data + BN_NIST_384_TOP *
-                               (carry-1), BN_NIST_384_TOP);
+       carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
+       mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = ~mask | (0-(size_t)carry);
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
        /*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);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
+       bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+#else
+       if (bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP))
+               bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+#endif
        /*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);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
+       bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
+#else
+       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
+               bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+#endif
        /*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);
-
-       if (carry)
-               bn_add_words(r_d, r_d, _384_data + BN_NIST_384_TOP *
-                               (carry-1), BN_NIST_384_TOP);
+#if BRANCH_FREE
+       carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
+       bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+       mask = 0-(size_t)carry;
+       res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 
+       nist_cp_bn(r_d, res, BN_NIST_384_TOP);
+#else
+       if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
+               bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
+#endif
        r->top = BN_NIST_384_TOP;
        bn_correct_top(r);
-       if (BN_ucmp(r, field) >= 0)
-               {
-               bn_sub_words(r_d, r_d, _nist_p_384, BN_NIST_384_TOP);
-               bn_correct_top(r);
-               }
-       bn_check_top(r);
+
        return 1;
-#else
+#else  /* BN_BITS!=32 */
        return 0;
 #endif
        }
@@ -679,10 +644,6 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 #define BN_NIST_521_TOP_MASK   (BN_ULONG)0x1FF
 #elif BN_BITS2 == 32
 #define BN_NIST_521_TOP_MASK   (BN_ULONG)0x1FF
-#elif BN_BITS2 == 16
-#define BN_NIST_521_TOP_MASK   (BN_ULONG)0x1FF
-#elif BN_BITS2 == 8
-#define BN_NIST_521_TOP_MASK   (BN_ULONG)0x1
 #endif
        int     top, ret = 0;
        BN_ULONG *r_d;