[ec_asn1.c] Avoid injecting seed when built-in matches

[openssl.git] / crypto / ec / ec_asn1.c

diff --git a/crypto/ec/ec_asn1.c b/crypto/ec/ec_asn1.c
index 502a3834353fbda38c9d9d0f3e8fdb4641e27233..c993821bb9130e4e079682fe8643e92a0f6e04dd 100644 (file)
--- a/crypto/ec/ec_asn1.c
+++ b/crypto/ec/ec_asn1.c
@@ -855,6 +855,20 @@ EC_GROUP *EC_GROUP_new_from_ecparameters(const ECPARAMETERS *params)
          * serialized using explicit parameters by default.
          */
         EC_GROUP_set_asn1_flag(ret, OPENSSL_EC_EXPLICIT_CURVE);
+
+        /*
+         * If the input params do not contain the optional seed field we make
+         * sure it is not added to the returned group.
+         *
+         * The seed field is not really used inside libcrypto anyway, and
+         * adding it to parsed explicit parameter keys would alter their DER
+         * encoding output (because of the extra field) which could impact
+         * applications fingerprinting keys by their DER encoding.
+         */
+        if (params->curve->seed == NULL) {
+            if (EC_GROUP_set_seed(ret, NULL, 0) != 1)
+                goto err;
+        }
     }
 
     ok = 1;