/*
 * Copyright 2011-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.crypto.keygen;

import java.security.SecureRandom;

/**
 * Factory for commonly used key generators. Public API for constructing a
 * {@link BytesKeyGenerator} or {@link StringKeyGenerator}.
 * @author Keith Donald
 */
public class KeyGenerators {

	/**
	 * Create a {@link BytesKeyGenerator} that uses a {@link SecureRandom} to generate
	 * keys of 8 bytes in length.
	 */
	public static BytesKeyGenerator secureRandom() {
		return new SecureRandomBytesKeyGenerator();
	}

	/**
	 * Create a {@link BytesKeyGenerator} that uses a {@link SecureRandom} to generate
	 * keys of a custom length.
	 * @param keyLength the key length in bytes, e.g. 16, for a 16 byte key.
	 */
	public static BytesKeyGenerator secureRandom(int keyLength) {
		return new SecureRandomBytesKeyGenerator(keyLength);
	}

	/**
	 * Create a {@link BytesKeyGenerator} that returns a single, shared
	 * {@link SecureRandom} key of a custom length.
	 * @param keyLength the key length in bytes, e.g. 16, for a 16 byte key.
	 */
	public static BytesKeyGenerator shared(int keyLength) {
		return new SharedKeyGenerator(secureRandom(keyLength).generateKey());
	}

	/**
	 * Creates a {@link StringKeyGenerator} that hex-encodes {@link SecureRandom} keys of
	 * 8 bytes in length. The hex-encoded string is keyLength * 2 characters in length.
	 */
	public static StringKeyGenerator string() {
		return new HexEncodingStringKeyGenerator(secureRandom());
	}

	// internal helpers

	private KeyGenerators() {
	}
}
