protected byte[] hash(byte[] bytes) throws UnknownAlgorithmException {
        return hash(bytes, new byte[0], DEFAULT_ITERATIONS);
    }
Hashes the specified byte array without a salt for a single iteration.

@param bytes the bytes to hash.
@return the hashed bytes.
@throws UnknownAlgorithmException if the configured {@link #getAlgorithmName() algorithmName} is not available.
crypto/hash/src/main/java/org/apache/shiro/crypto/hash/SimpleHash.java