/* Copyright 2004, 2005, 2006, 2007 Acegi Technology Pty Limited
 *
 * 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.authentication.encoding;

import java.io.UnsupportedEncodingException;

import org.springframework.security.core.codec.Base64;
import org.springframework.security.core.codec.Hex;

/**
 * MD4 implementation of PasswordEncoder.
 * <p>
 * If a <code>null</code> password is presented, it will be treated as an empty <code>String</code> ("") password.
 * <p>
 * As MD4 is a one-way hash, the salt can contain any characters.
 * <p>
 * <b>NOTE:</b> This password encoder is only included for backwards compatability with legacy applications, it's not
 * secure, don't use it for anything new!
 *
 * @author Alan Stewart
 */
public class Md4PasswordEncoder extends BaseDigestPasswordEncoder {

    //~ Methods ========================================================================================================

    /**
     * Encodes the rawPass using an MD4 message digest. If a salt is specified it will be merged with the password
     * before encoding.
     *
     * @param rawPass The plain text password
     * @param salt The salt to sprinkle
     * @return Hex string of password digest (or base64 encoded string if encodeHashAsBase64 is enabled.
     */
    public String encodePassword(String rawPass, Object salt) {
        String saltedPass = mergePasswordAndSalt(rawPass, salt, false);

        byte[] passBytes;

        try {
            passBytes = saltedPass.getBytes("UTF-8");
        } catch (UnsupportedEncodingException e) {
            throw new IllegalStateException("UTF-8 not supported!");
        }

        Md4 md4 = new Md4();
        md4.update(passBytes, 0, passBytes.length);

        byte[] resBuf = md4.digest();

        if (getEncodeHashAsBase64()) {
            return new String(Base64.encode(resBuf));
        } else {
            return new String(Hex.encode(resBuf));
        }
    }

    /**
     * Takes a previously encoded password and compares it with a raw password after mixing in the salt and
     * encoding that value.
     *
     * @param encPass previously encoded password
     * @param rawPass plain text password
     * @param salt salt to mix into password
     * @return true or false
     */
    public boolean isPasswordValid(String encPass, String rawPass, Object salt) {
        String pass1 = "" + encPass;
        String pass2 = encodePassword(rawPass, salt);
        return pass1.equals(pass2);
    }

    public String getAlgorithm() {
        return "MD4";
    }
}
