将 SecretKey 转换为字节，如何将其转换回 SecretKey？答案

【问题标题】：Converted SecretKey into bytes, how to convert it back to a SecretKey?将 SecretKey 转换为字节，如何将其转换回 SecretKey？
【发布时间】：2011-07-18 20:55:32
【问题描述】：

我使用以下代码将密钥转换为字节

SecretKey key = KeyGenerator.getInstance("DES").generateKey();
byte[] bkey=key.getEncoded();

现在我如何从bkey 获取密钥？我试过了：

SecretKeySpec secretkey = new SecretKeySpec(bkey,"DES");   
SecretKeyFactory sfkey = SecretKeyFactory.getInstance("DES");
SecretKey skey = sfkey.generateSecret(secretkey);

我收到以下错误：

Error during Exception java.security.spec.InvalidKeySpecException: Inappropriate key specification

【问题讨论】：

为什么需要这样做？只需将 key 传递给您的密码即可。
@Bruno Ya 但我只是在学习 DES 的工作原理
@BrunoRohée：有些人只是希望他们的问题得到回答，而不是居高临下的精英回应。这样的评论让没有经验的用户不敢发表他们的问题；我会知道，因为我自己（现在仍然）处于那种情况......
@araisbec 这不是一个答案，而是一个评论，有些人确实很欣赏在他们的游荡将他们直接引向深渊时被提早阻止。在这个网站上，人们使用非常不安全的加密货币的例子比比皆是，因为没有人足够早地告诉他们。
@BrunoRohée，当您说明文时，我假设您正在谈论 PKCS 容器。以明文形式保存的密钥是否小于其以字节格式保存的大小？

标签： java security byte des

【解决方案1】：

这应该可以工作

    SecretKey key = KeyGenerator.getInstance("DES").generateKey();
    byte[] data = key.getEncoded();
    SecretKey key2 = new SecretKeySpec(data, 0, data.length, "DES");

【讨论】：

【解决方案2】：

试试这段代码...

import javax.crypto.Cipher;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.InvalidKeyException;

public class DESede {
    private static String algorithm = "DESede";
    private static Key key = null;
    private static SecretKey secretKey = null;
    private static Cipher cipher = null;
    private static DESede obj = new DESede();

    private DESede() {
        try {
            key = KeyGenerator.getInstance(algorithm).generateKey();
            KeyGenerator.getInstance(algorithm).getProvider();
            byte[] keyBytes = key.getEncoded();
            String keyFormat = key.getFormat();
            String keyAlgorithm = key.getAlgorithm();
            String keyString = new String(keyBytes);
            System.out.println("Key Format::" + keyFormat);
            System.out.println("Key Algorithm::" + keyAlgorithm);
            System.out.println("Key String::" + keyString);
            keyString.getBytes();
            secretKey = new SecretKeySpec(keyBytes, 0, keyBytes.length, "DESede");
            byte[] secretKeyBytes = key.getEncoded();
            String secretKeyFormat = key.getFormat();
            String secretKeyAlgorithm = key.getAlgorithm();
            String secretKeyString = new String(secretKeyBytes);
            System.out.println("Secret Key Format::" + secretKeyFormat);
            System.out.println("Secret Key Algorithm::" + secretKeyAlgorithm);
            System.out.println("Secret Key String::" + secretKeyString);
            String keyNewString = "bXŒ*êÂÕê›æOÄ’Îý‘ãô|8¶Ë1";
            byte[] keyNewBytes = keyString.getBytes();
            secretKey = new SecretKeySpec(keyBytes, 0, keyBytes.length, "DESede");
            cipher = Cipher.getInstance(algorithm);
        } catch (Exception e) {
        }
    }

    public static DESede getInstance() {
        return obj;
    }

    public static byte[] encrypt(String input) throws InvalidKeyException,
            BadPaddingException, IllegalBlockSizeException {
        System.out.println("Inside encrypt()");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] inputBytes = input.getBytes();
        System.out.println("Exit encrypt()");
        return cipher.doFinal(inputBytes);
    }

    public static String decrypt(byte[] encryptionBytes)
            throws InvalidKeyException, BadPaddingException,
            IllegalBlockSizeException {
        System.out.println("Inside decrypt()");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] recoveredBytes = cipher.doFinal(encryptionBytes);
        String recovered = new String(recoveredBytes);
        System.out.println("Exiting decrypt()");
        return recovered;
    }

    public static void main(String args[]) throws InvalidKeyException,
            BadPaddingException, IllegalBlockSizeException {
        byte[] encryptedValue = DESede.encrypt("plz try encrypt and decrypt me");
        System.out.println("encryptedValue::" + encryptedValue);
        String decryptedValue = DESede.decrypt(encryptedValue);
        System.out.println("decryptedValue::" + decryptedValue);
    }
}

【讨论】：