Fix various mistakes in ec_GFp_nistp_recode_scalar_bits comment.

[oweals/openssl.git] / crypto / ec / ecp_nistp521.c

diff --git a/crypto/ec/ecp_nistp521.c b/crypto/ec/ecp_nistp521.c
index 9d264f63d40dfc04131f63f7622001873ebe6c42..e31b85c5f755c06ba9651b6bd4c94a25d07a27ec 100644 (file)
--- a/crypto/ec/ecp_nistp521.c
+++ b/crypto/ec/ecp_nistp521.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2011-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -40,17 +40,16 @@ NON_EMPTY_TRANSLATION_UNIT
 # include <openssl/err.h>
 # include "ec_lcl.h"
 
-# if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+# if defined(__SIZEOF_INT128__) && __SIZEOF_INT128__==16
   /* even with gcc, the typedef won't work for 32-bit platforms */
 typedef __uint128_t uint128_t;  /* nonstandard; implemented by gcc on 64-bit
                                  * platforms */
 # else
-#  error "Need GCC 3.1 or later to define type uint128_t"
+#  error "Your compiler doesn't appear to support 128-bit integer types"
 # endif
 
 typedef uint8_t u8;
 typedef uint64_t u64;
-typedef int64_t s64;
 
 /*
  * The underlying field. P521 operates over GF(2^521-1). We can serialise an
@@ -358,10 +357,15 @@ static void felem_diff64(felem out, const felem in)
 static void felem_diff_128_64(largefelem out, const felem in)
 {
     /*
-     * In order to prevent underflow, we add 0 mod p before subtracting.
+     * In order to prevent underflow, we add 64p mod p (which is equivalent
+     * to 0 mod p) before subtracting. p is 2^521 - 1, i.e. in binary a 521
+     * digit number with all bits set to 1. See "The representation of field
+     * elements" comment above for a description of how limbs are used to
+     * represent a number. 64p is represented with 8 limbs containing a number
+     * with 58 bits set and one limb with a number with 57 bits set.
      */
-    static const limb two63m6 = (((limb) 1) << 62) - (((limb) 1) << 5);
-    static const limb two63m5 = (((limb) 1) << 62) - (((limb) 1) << 4);
+    static const limb two63m6 = (((limb) 1) << 63) - (((limb) 1) << 6);
+    static const limb two63m5 = (((limb) 1) << 63) - (((limb) 1) << 5);
 
     out[0] += two63m6 - in[0];
     out[1] += two63m5 - in[1];
@@ -867,7 +871,7 @@ static limb felem_is_zero(const felem in)
      * We know that ftmp[i] < 2^63, therefore the only way that the top bit
      * can be set is if is_zero was 0 before the decrement.
      */
-    is_zero = ((s64) is_zero) >> 63;
+    is_zero = 0 - (is_zero >> 63);
 
     is_p = ftmp[0] ^ kPrime[0];
     is_p |= ftmp[1] ^ kPrime[1];
@@ -880,7 +884,7 @@ static limb felem_is_zero(const felem in)
     is_p |= ftmp[8] ^ kPrime[8];
 
     is_p--;
-    is_p = ((s64) is_p) >> 63;
+    is_p = 0 - (is_p >> 63);
 
     is_zero |= is_p;
     return is_zero;
@@ -951,7 +955,7 @@ static void felem_contract(felem out, const felem in)
     is_p &= is_p << 4;
     is_p &= is_p << 2;
     is_p &= is_p << 1;
-    is_p = ((s64) is_p) >> 63;
+    is_p = 0 - (is_p >> 63);
     is_p = ~is_p;
 
     /* is_p is 0 iff |out| == 2^521-1 and all ones otherwise */
@@ -977,7 +981,7 @@ static void felem_contract(felem out, const felem in)
     is_greater |= is_greater << 4;
     is_greater |= is_greater << 2;
     is_greater |= is_greater << 1;
-    is_greater = ((s64) is_greater) >> 63;
+    is_greater = 0 - (is_greater >> 63);
 
     out[0] -= kPrime[0] & is_greater;
     out[1] -= kPrime[1] & is_greater;
@@ -1648,6 +1652,7 @@ const EC_METHOD *EC_GFp_nistp521_method(void)
         ec_GFp_nist_field_mul,
         ec_GFp_nist_field_sqr,
         0 /* field_div */ ,
+        ec_GFp_simple_field_inv,
         0 /* field_encode */ ,
         0 /* field_decode */ ,
         0,                      /* field_set_to_one */
@@ -1659,7 +1664,12 @@ const EC_METHOD *EC_GFp_nistp521_method(void)
         ec_key_simple_generate_public_key,
         0, /* keycopy */
         0, /* keyfinish */
-        ecdh_simple_compute_key
+        ecdh_simple_compute_key,
+        0, /* field_inverse_mod_ord */
+        0, /* blind_coordinates */
+        0, /* ladder_pre */
+        0, /* ladder_step */
+        0  /* ladder_post */
     };
 
     return &ret;
@@ -1670,7 +1680,7 @@ const EC_METHOD *EC_GFp_nistp521_method(void)
  * FUNCTIONS TO MANAGE PRECOMPUTATION
  */
 
-static NISTP521_PRE_COMP *nistp521_pre_comp_new()
+static NISTP521_PRE_COMP *nistp521_pre_comp_new(void)
 {
     NISTP521_PRE_COMP *ret = OPENSSL_zalloc(sizeof(*ret));
 
@@ -1851,7 +1861,6 @@ int ec_GFp_nistp521_points_mul(const EC_GROUP *group, EC_POINT *r,
     int ret = 0;
     int j;
     int mixed = 0;
-    BN_CTX *new_ctx = NULL;
     BIGNUM *x, *y, *z, *tmp_scalar;
     felem_bytearray g_secret;
     felem_bytearray *secrets = NULL;
@@ -1868,9 +1877,6 @@ int ec_GFp_nistp521_points_mul(const EC_GROUP *group, EC_POINT *r,
     const EC_POINT *p = NULL;
     const BIGNUM *p_scalar = NULL;
 
-    if (ctx == NULL)
-        if ((ctx = new_ctx = BN_CTX_new()) == NULL)
-            return 0;
     BN_CTX_start(ctx);
     x = BN_CTX_get(ctx);
     y = BN_CTX_get(ctx);
@@ -2037,7 +2043,6 @@ int ec_GFp_nistp521_points_mul(const EC_GROUP *group, EC_POINT *r,
  err:
     BN_CTX_end(ctx);
     EC_POINT_free(generator);
-    BN_CTX_free(new_ctx);
     OPENSSL_free(secrets);
     OPENSSL_free(pre_comp);
     OPENSSL_free(tmp_felems);
@@ -2072,7 +2077,7 @@ int ec_GFp_nistp521_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
         goto err;
     BN_bin2bn(nistp521_curve_params[3], sizeof(felem_bytearray), x);
     BN_bin2bn(nistp521_curve_params[4], sizeof(felem_bytearray), y);
-    if (!EC_POINT_set_affine_coordinates_GFp(group, generator, x, y, ctx))
+    if (!EC_POINT_set_affine_coordinates(group, generator, x, y, ctx))
         goto err;
     if ((pre = nistp521_pre_comp_new()) == NULL)
         goto err;