com.charandeepmatta.oracle.sqldeveloper.DecodePasswordHash.java Source code

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Here is the source code for com.charandeepmatta.oracle.sqldeveloper.DecodePasswordHash.java

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/**
 * Credit -> git://gist.github.com/1846191.git
 *
 *  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 com.charandeepmatta.oracle.sqldeveloper;

import static org.apache.commons.lang.StringUtils.isEmpty;
import static org.apache.commons.lang.StringUtils.trimToEmpty;

import java.security.GeneralSecurityException;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class DecodePasswordHash {
    private final String passwordHash;

    public DecodePasswordHash(final String passwordHash) {
        this.passwordHash = passwordHash;
    }

    private String decode() {
        int hashLength = passwordHash.length();
        byte[] secret = new byte[hashLength / 2];
        for (int i = 0; i < hashLength; i += 2) {
            String pair = passwordHash.substring(i, i + 2);
            secret[i / 2] = (byte) Integer.parseInt(pair, 16);
        }
        try {
            return new String(decryptPassword(secret));
        } catch (GeneralSecurityException e) {
            throw new RuntimeException(e);
        }
    }

    private byte[] decryptPassword(final byte[] result) throws GeneralSecurityException {
        byte constant = result[0];
        if (constant != (byte) 5) {
            throw new IllegalArgumentException();
        }
        byte[] secretKey = new byte[8];
        System.arraycopy(result, 1, secretKey, 0, 8);
        byte[] encryptedPassword = new byte[result.length - 9];
        System.arraycopy(result, 9, encryptedPassword, 0, encryptedPassword.length);
        byte[] iv = new byte[8];
        for (int i = 0; i < iv.length; i++) {
            iv[i] = 0;
        }
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(secretKey, "DES"), new IvParameterSpec(iv));
        return cipher.doFinal(encryptedPassword);
    }

    public static void main(final String[] args) {
        String passwordHash = getValidatedPasswordHash(args);
        String decodedPassword = new DecodePasswordHash(passwordHash).decode();
        System.out.println(passwordHash + " = " + decodedPassword);
    }

    private static String getValidatedPasswordHash(final String[] args) {
        String passwordHash = trimToEmpty(getPasswordHash(args));
        if (isEmpty(passwordHash) || passwordHash.length() % 2 != 0) {
            System.err.println("Usage: java DecodePasswordHash <password>");
            System.err.println("Password must consist of hex pairs. Length must be even.");
            System.exit(1);
        }
        return passwordHash;
    }

    private static String getPasswordHash(final String[] args) {
        if (args.length != 1) {
            return System.getProperty("passwordHash");
        }
        return args[0];
    }
}