[openssl-commits] [openssl] master update

[Matt Caswell]

The branch master has been updated
       via  30cd4ff294252c4b6a4b69cbef6a5b4117705d22 (commit)
      from  747e16398d704a667cc99f8a0b1912c36b7de52d (commit)


- Log -----------------------------------------------------------------
commit 30cd4ff294252c4b6a4b69cbef6a5b4117705d22
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>

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

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 9bba26e..97c5906 100644
--- a/crypto/ec/ec_asn1.c
+++ b/crypto/ec/ec_asn1.c
@@ -1110,7 +1110,7 @@ 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 ||
@@ -1126,18 +1126,32 @@ 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 (!ASN1_OCTET_STRING_set(priv_key->privateKey, buffer, buf_len)) {
         ECerr(EC_F_I2D_ECPRIVATEKEY, ERR_R_ASN1_LIB);
         goto err;