Add secure DSA nonce flag.

This change adds the option to calculate (EC)DSA nonces by hashing the
message and private key along with entropy to avoid leaking the private
key if the PRNG fails.

crypto/ecdsa/ecs_err.c

@@ -1,6 +1,6 @@
 /* crypto/ecdsa/ecs_err.c */
 /* ====================================================================
- * Copyright (c) 1999-2006 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1999-2013 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -84,6 +84,7 @@ static ERR_STRING_DATA ECDSA_str_reasons[]=
 {ERR_REASON(ECDSA_R_ERR_EC_LIB)          ,"err ec lib"},
 {ERR_REASON(ECDSA_R_MISSING_PARAMETERS)  ,"missing parameters"},
 {ERR_REASON(ECDSA_R_NEED_NEW_SETUP_VALUES),"need new setup values"},
+{ERR_REASON(ECDSA_R_NONCE_CANNOT_BE_PRECOMPUTED),"nonce cannot be precomputed"},
 {ERR_REASON(ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED),"random number generation failed"},
 {ERR_REASON(ECDSA_R_SIGNATURE_MALLOC_FAILED),"signature malloc failed"},
 {0,NULL}