X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fec%2Fecp_nistz256.c;h=b0564bdbd04c56f9dc1bd63e3fd5ad9e5e9c5d8b;hp=6bae3d1f82497c069b7cf9feb3a5e22c837ded20;hb=453eccd63ad6ba19f6a3fcac37df05daf6cc1021;hpb=ab4f2026b7ff8902d70ddd75adc080fc66ffd642

diff --git a/crypto/ec/ecp_nistz256.c b/crypto/ec/ecp_nistz256.c
index 6bae3d1f82..b0564bdbd0 100644
--- a/crypto/ec/ecp_nistz256.c
+++ b/crypto/ec/ecp_nistz256.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2014-2018 The OpenSSL Project Authors. All Rights Reserved.
  * Copyright (c) 2014, Intel Corporation. All Rights Reserved.
  * Copyright (c) 2015, CloudFlare, Inc.
  *
@@ -1104,28 +1104,12 @@ __owur static int ecp_nistz256_set_from_affine(EC_POINT *out, const EC_GROUP *gr
                                                const P256_POINT_AFFINE *in,
                                                BN_CTX *ctx)
 {
-    BIGNUM *x, *y;
-    BN_ULONG d_x[P256_LIMBS], d_y[P256_LIMBS];
     int ret = 0;
 
-    x = BN_new();
-    if (x == NULL)
-        return 0;
-    y = BN_new();
-    if (y == NULL) {
-        BN_free(x);
-        return 0;
-    }
-    memcpy(d_x, in->X, sizeof(d_x));
-    bn_set_static_words(x, d_x, P256_LIMBS);
-
-    memcpy(d_y, in->Y, sizeof(d_y));
-    bn_set_static_words(y, d_y, P256_LIMBS);
-
-    ret = EC_POINT_set_affine_coordinates_GFp(group, out, x, y, ctx);
-
-    BN_free(x);
-    BN_free(y);
+    if ((ret = bn_set_words(out->X, in->X, P256_LIMBS))
+        && (ret = bn_set_words(out->Y, in->Y, P256_LIMBS))
+        && (ret = bn_set_words(out->Z, ONE, P256_LIMBS)))
+        out->Z_is_one = 1;
 
     return ret;
 }
@@ -1139,12 +1123,10 @@ __owur static int ecp_nistz256_points_mul(const EC_GROUP *group,
                                           const BIGNUM *scalars[], BN_CTX *ctx)
 {
     int i = 0, ret = 0, no_precomp_for_generator = 0, p_is_infinity = 0;
-    size_t j;
     unsigned char p_str[33] = { 0 };
     const PRECOMP256_ROW *preComputedTable = NULL;
     const NISTZ256_PRE_COMP *pre_comp = NULL;
     const EC_POINT *generator = NULL;
-    BN_CTX *new_ctx = NULL;
     const BIGNUM **new_scalars = NULL;
     const EC_POINT **new_points = NULL;
     unsigned int idx = 0;
@@ -1162,27 +1144,6 @@ __owur static int ecp_nistz256_points_mul(const EC_GROUP *group,
         return 0;
     }
 
-    if (group->meth != r->meth) {
-        ECerr(EC_F_ECP_NISTZ256_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS);
-        return 0;
-    }
-
-    if ((scalar == NULL) && (num == 0))
-        return EC_POINT_set_to_infinity(group, r);
-
-    for (j = 0; j < num; j++) {
-        if (group->meth != points[j]->meth) {
-            ECerr(EC_F_ECP_NISTZ256_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS);
-            return 0;
-        }
-    }
-
-    if (ctx == NULL) {
-        ctx = new_ctx = BN_CTX_new();
-        if (ctx == NULL)
-            goto err;
-    }
-
     BN_CTX_start(ctx);
 
     if (scalar) {
@@ -1204,9 +1165,9 @@ __owur static int ecp_nistz256_points_mul(const EC_GROUP *group,
             if (pre_comp_generator == NULL)
                 goto err;
 
+            ecp_nistz256_gather_w7(&p.a, pre_comp->precomp[0], 1);
             if (!ecp_nistz256_set_from_affine(pre_comp_generator,
-                                              group, pre_comp->precomp[0],
-                                              ctx)) {
+                                              group, &p.a, ctx)) {
                 EC_POINT_free(pre_comp_generator);
                 goto err;
             }
@@ -1378,9 +1339,7 @@ __owur static int ecp_nistz256_points_mul(const EC_GROUP *group,
     ret = 1;
 
 err:
-    if (ctx)
-        BN_CTX_end(ctx);
-    BN_CTX_free(new_ctx);
+    BN_CTX_end(ctx);
     OPENSSL_free(new_points);
     OPENSSL_free(new_scalars);
     return ret;
@@ -1512,22 +1471,17 @@ void ecp_nistz256_ord_sqr_mont(BN_ULONG res[P256_LIMBS],
                                int rep);
 
 static int ecp_nistz256_inv_mod_ord(const EC_GROUP *group, BIGNUM *r,
-                                    BIGNUM *x, BN_CTX *ctx)
+                                    const BIGNUM *x, BN_CTX *ctx)
 {
     /* RR = 2^512 mod ord(p256) */
-    static const BN_ULONG RR[P256_LIMBS]  = { TOBN(0x83244c95,0xbe79eea2),
-                                              TOBN(0x4699799c,0x49bd6fa6),
-                                              TOBN(0x2845b239,0x2b6bec59),
-                                              TOBN(0x66e12d94,0xf3d95620) };
+    static const BN_ULONG RR[P256_LIMBS]  = {
+        TOBN(0x83244c95,0xbe79eea2), TOBN(0x4699799c,0x49bd6fa6),
+        TOBN(0x2845b239,0x2b6bec59), TOBN(0x66e12d94,0xf3d95620)
+    };
     /* The constant 1 (unlike ONE that is one in Montgomery representation) */
-    static const BN_ULONG one[P256_LIMBS] = { TOBN(0,1),TOBN(0,0),
-                                              TOBN(0,0),TOBN(0,0) };
-    /* expLo - the low 128bit of the exponent we use (ord(p256) - 2),
-     * split into 4bit windows */
-    static const unsigned char expLo[32]  = { 0xb,0xc,0xe,0x6,0xf,0xa,0xa,0xd,
-                                              0xa,0x7,0x1,0x7,0x9,0xe,0x8,0x4,
-                                              0xf,0x3,0xb,0x9,0xc,0xa,0xc,0x2,
-                                              0xf,0xc,0x6,0x3,0x2,0x5,0x4,0xf };
+    static const BN_ULONG one[P256_LIMBS] = {
+        TOBN(0,1), TOBN(0,0), TOBN(0,0), TOBN(0,0)
+    };
     /*
      * We don't use entry 0 in the table, so we omit it and address
      * with -1 offset.
@@ -1535,6 +1489,10 @@ static int ecp_nistz256_inv_mod_ord(const EC_GROUP *group, BIGNUM *r,
     BN_ULONG table[15][P256_LIMBS];
     BN_ULONG out[P256_LIMBS], t[P256_LIMBS];
     int i, ret = 0;
+    enum {
+        i_1 = 0, i_10,     i_11,     i_101, i_111, i_1010, i_1111,
+        i_10101, i_101010, i_101111, i_x6,  i_x8,  i_x16,  i_x32
+    };
 
     /*
      * Catch allocation failure early.
@@ -1561,6 +1519,10 @@ static int ecp_nistz256_inv_mod_ord(const EC_GROUP *group, BIGNUM *r,
     }
 
     ecp_nistz256_ord_mul_mont(table[0], t, RR);
+#if 0
+    /*
+     * Original sparse-then-fixed-window algorithm, retained for reference.
+     */
     for (i = 2; i < 16; i += 2) {
         ecp_nistz256_ord_sqr_mont(table[i-1], table[i/2-1], 1);
         ecp_nistz256_ord_mul_mont(table[i], table[i-1], table[0]);
@@ -1586,13 +1548,81 @@ static int ecp_nistz256_inv_mod_ord(const EC_GROUP *group, BIGNUM *r,
     ecp_nistz256_ord_mul_mont(out, out, t);         /* ffffffff00000000ffffffffffffffff */
 
     /*
-     * The bottom 128 bit of the exponent are easier done with a table
+     * The bottom 128 bit of the exponent are processed with fixed 4-bit window
      */
     for(i = 0; i < 32; i++) {
+        /* expLo - the low 128 bits of the exponent we use (ord(p256) - 2),
+         * split into nibbles */
+        static const unsigned char expLo[32]  = {
+            0xb,0xc,0xe,0x6,0xf,0xa,0xa,0xd,0xa,0x7,0x1,0x7,0x9,0xe,0x8,0x4,
+            0xf,0x3,0xb,0x9,0xc,0xa,0xc,0x2,0xf,0xc,0x6,0x3,0x2,0x5,0x4,0xf
+        };
+
         ecp_nistz256_ord_sqr_mont(out, out, 4);
         /* The exponent is public, no need in constant-time access */
         ecp_nistz256_ord_mul_mont(out, out, table[expLo[i]-1]);
     }
+#else
+    /*
+     * https://briansmith.org/ecc-inversion-addition-chains-01#p256_scalar_inversion
+     *
+     * Even though this code path spares 12 squarings, 4.5%, and 13
+     * multiplications, 25%, on grand scale sign operation is not that
+     * much faster, not more that 2%...
+     */
+
+    /* pre-calculate powers */
+    ecp_nistz256_ord_sqr_mont(table[i_10], table[i_1], 1);
+
+    ecp_nistz256_ord_mul_mont(table[i_11], table[i_1], table[i_10]);
+
+    ecp_nistz256_ord_mul_mont(table[i_101], table[i_11], table[i_10]);
+
+    ecp_nistz256_ord_mul_mont(table[i_111], table[i_101], table[i_10]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_1010], table[i_101], 1);
+
+    ecp_nistz256_ord_mul_mont(table[i_1111], table[i_1010], table[i_101]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_10101], table[i_1010], 1);
+    ecp_nistz256_ord_mul_mont(table[i_10101], table[i_10101], table[i_1]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_101010], table[i_10101], 1);
+
+    ecp_nistz256_ord_mul_mont(table[i_101111], table[i_101010], table[i_101]);
+
+    ecp_nistz256_ord_mul_mont(table[i_x6], table[i_101010], table[i_10101]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_x8], table[i_x6], 2);
+    ecp_nistz256_ord_mul_mont(table[i_x8], table[i_x8], table[i_11]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_x16], table[i_x8], 8);
+    ecp_nistz256_ord_mul_mont(table[i_x16], table[i_x16], table[i_x8]);
+
+    ecp_nistz256_ord_sqr_mont(table[i_x32], table[i_x16], 16);
+    ecp_nistz256_ord_mul_mont(table[i_x32], table[i_x32], table[i_x16]);
+
+    /* calculations */
+    ecp_nistz256_ord_sqr_mont(out, table[i_x32], 64);
+    ecp_nistz256_ord_mul_mont(out, out, table[i_x32]);
+
+    for (i = 0; i < 27; i++) {
+        static const struct { unsigned char p, i; } chain[27] = {
+            { 32, i_x32 }, { 6,  i_101111 }, { 5,  i_111    },
+            { 4,  i_11  }, { 5,  i_1111   }, { 5,  i_10101  },
+            { 4,  i_101 }, { 3,  i_101    }, { 3,  i_101    },
+            { 5,  i_111 }, { 9,  i_101111 }, { 6,  i_1111   },
+            { 2,  i_1   }, { 5,  i_1      }, { 6,  i_1111   },
+            { 5,  i_111 }, { 4,  i_111    }, { 5,  i_111    },
+            { 5,  i_101 }, { 3,  i_11     }, { 10, i_101111 },
+            { 2,  i_11  }, { 5,  i_11     }, { 5,  i_11     },
+            { 3,  i_1   }, { 7,  i_10101  }, { 6,  i_1111   }
+        };
+
+        ecp_nistz256_ord_sqr_mont(out, out, chain[i].p);
+        ecp_nistz256_ord_mul_mont(out, out, table[chain[i].i]);
+    }
+#endif
     ecp_nistz256_ord_mul_mont(out, out, one);
 
     /*
@@ -1659,7 +1689,11 @@ const EC_METHOD *EC_GFp_nistz256_method(void)
         0, /* keycopy */
         0, /* keyfinish */
         ecdh_simple_compute_key,
-        ecp_nistz256_inv_mod_ord                    /* can be #defined-ed NULL */
+        ecp_nistz256_inv_mod_ord,                   /* can be #define-d NULL */
+        0,                                          /* blind_coordinates */
+        0,                                          /* ladder_pre */
+        0,                                          /* ladder_step */
+        0                                           /* ladder_post */
     };
 
     return &ret;