public static String toEcdsaAlgo(HashType hash) throws GeneralSecurityException {
    Validators.validateSignatureHash(hash);
    return hash + "withECDSA";
  }
Returns the Ecdsa algorithm name corresponding to a hash type.

@param hash the hash type
@return the JCE's Ecdsa algorithm name for the hash.
@throws GeneralSecurityException if {@code hash} is not supported or is not safe for digital
    signature.
java_src/src/main/java/com/google/crypto/tink/subtle/SubtleUtil.java