[openssl-commits] [openssl] OpenSSL_1_0_2-stable update

[Matt Caswell]

The branch OpenSSL_1_0_2-stable has been updated
       via  3d5bb773ecd78f75984fb096bb0be7808d3dc18d (commit)
      from  c8ece537e341126b979b185b32fc716db6db9f0c (commit)


- Log -----------------------------------------------------------------
commit 3d5bb773ecd78f75984fb096bb0be7808d3dc18d
Author: Douglas E Engert <deengert at gmail.com>
Date:   Wed Mar 25 23:52:28 2015 +0000

    Ensure EC private keys retain leading zeros
    
    RFC5915 requires the use of the I2OSP primitive as defined in RFC3447
    for storing an EC Private Key. This converts the private key into an
    OCTETSTRING and retains any leading zeros. This commit ensures that those
    leading zeros are present if required.
    
    Reviewed-by: Andy Polyakov <appro at openssl.org>
    (cherry picked from commit 30cd4ff294252c4b6a4b69cbef6a5b4117705d22)
    
    Conflicts:
    	crypto/ec/ec_asn1.c

-----------------------------------------------------------------------

Summary of changes:
 crypto/ec/ec_asn1.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/crypto/ec/ec_asn1.c b/crypto/ec/ec_asn1.c
index b4b0e9f..4ad8494 100644
--- a/crypto/ec/ec_asn1.c
+++ b/crypto/ec/ec_asn1.c
@@ -1114,7 +1114,7 @@ int i2d_ECPrivateKey(EC_KEY *a, unsigned char **out)
 {
     int ret = 0, ok = 0;
     unsigned char *buffer = NULL;
-    size_t buf_len = 0, tmp_len;
+    size_t buf_len = 0, tmp_len, bn_len;
     EC_PRIVATEKEY *priv_key = NULL;
 
     if (a == NULL || a->group == NULL || a->priv_key == NULL ||
@@ -1130,18 +1130,32 @@ int i2d_ECPrivateKey(EC_KEY *a, unsigned char **out)
 
     priv_key->version = a->version;
 
-    buf_len = (size_t)BN_num_bytes(a->priv_key);
+    bn_len = (size_t)BN_num_bytes(a->priv_key);
+
+    /* Octetstring may need leading zeros if BN is to short */
+
+    buf_len = (EC_GROUP_get_degree(a->group) + 7) / 8;
+
+    if (bn_len > buf_len) {
+        ECerr(EC_F_I2D_ECPRIVATEKEY, EC_R_BUFFER_TOO_SMALL);
+        goto err;
+    }
+
     buffer = OPENSSL_malloc(buf_len);
     if (buffer == NULL) {
         ECerr(EC_F_I2D_ECPRIVATEKEY, ERR_R_MALLOC_FAILURE);
         goto err;
     }
 
-    if (!BN_bn2bin(a->priv_key, buffer)) {
+    if (!BN_bn2bin(a->priv_key, buffer + buf_len - bn_len)) {
         ECerr(EC_F_I2D_ECPRIVATEKEY, ERR_R_BN_LIB);
         goto err;
     }
 
+    if (buf_len - bn_len > 0) {
+        memset(buffer, 0, buf_len - bn_len);
+    }
+
     if (!M_ASN1_OCTET_STRING_set(priv_key->privateKey, buffer, buf_len)) {
         ECerr(EC_F_I2D_ECPRIVATEKEY, ERR_R_ASN1_LIB);
         goto err;