[tor-commits] [tor/master] Use safe_mem_is_zero for checking curve25519 output for 0-ness

[nickm at torproject.org]

commit 5f219ddd029348df2d384fca5012d96957885cbc
Author: Nick Mathewson <nickm at torproject.org>
Date:   Tue Dec 25 22:25:09 2012 -0500

    Use safe_mem_is_zero for checking curve25519 output for 0-ness
    
    This should make the intent more explicit.  Probably needless, though.
---
 src/common/crypto_curve25519.c |    6 +-----
 src/or/onion_ntor.c            |   24 ++++--------------------
 2 files changed, 5 insertions(+), 25 deletions(-)

diff --git a/src/common/crypto_curve25519.c b/src/common/crypto_curve25519.c
index 6034706..f3ecdb5 100644
--- a/src/common/crypto_curve25519.c
+++ b/src/common/crypto_curve25519.c
@@ -49,11 +49,7 @@ curve25519_impl(uint8_t *output, const uint8_t *secret,
 int
 curve25519_public_key_is_ok(const curve25519_public_key_t *key)
 {
-  static const uint8_t zero[] =
-    "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
-    "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
-
-  return tor_memneq(key->public_key, zero, CURVE25519_PUBKEY_LEN);
+  return !safe_mem_is_zero(key->public_key, CURVE25519_PUBKEY_LEN);
 }
 
 /** Generate a new keypair and return the secret key.  If <b>extra_strong</b>
diff --git a/src/or/onion_ntor.c b/src/or/onion_ntor.c
index 8eab55a..b601d1e 100644
--- a/src/or/onion_ntor.c
+++ b/src/or/onion_ntor.c
@@ -167,18 +167,10 @@ onion_skin_ntor_server_handshake(const uint8_t *onion_skin,
 
   /* build secret_input */
   curve25519_handshake(si, &s.seckey_y, &s.pubkey_X);
-  bad = tor_memeq(si,
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00", 32);
+  bad = safe_mem_is_zero(si, CURVE25519_OUTPUT_LEN);
   si += CURVE25519_OUTPUT_LEN;
   curve25519_handshake(si, &keypair_bB->seckey, &s.pubkey_X);
-  bad |= tor_memeq(si,
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00", 32);
+  bad |= safe_mem_is_zero(si, CURVE25519_OUTPUT_LEN);
   si += CURVE25519_OUTPUT_LEN;
 
   APPEND(si, my_node_id, DIGEST_LEN);
@@ -257,19 +249,11 @@ onion_skin_ntor_client_handshake(
 
   /* Compute secret_input */
   curve25519_handshake(si, &handshake_state->seckey_x, &s.pubkey_Y);
-  bad = tor_memeq(si,
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00"
-                  "\x00\x00\x00\x00\x00\x00\x00\x00", 32);
+  bad = safe_mem_is_zero(si, CURVE25519_OUTPUT_LEN);
   si += CURVE25519_OUTPUT_LEN;
   curve25519_handshake(si, &handshake_state->seckey_x,
                        &handshake_state->pubkey_B);
-  bad |= tor_memeq(si,
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00"
-                   "\x00\x00\x00\x00\x00\x00\x00\x00", 32);
+  bad |= safe_mem_is_zero(si, CURVE25519_OUTPUT_LEN);
   si += CURVE25519_OUTPUT_LEN;
   APPEND(si, handshake_state->router_id, DIGEST_LEN);
   APPEND(si, handshake_state->pubkey_B.public_key, CURVE25519_PUBKEY_LEN);