Java AES并使用我自己的密钥


88

我想使用我自己的密钥使用AES加密字符串。但是我在密钥的位长上遇到了麻烦。您能否查看我的代码并查看需要修复/更改的内容。

public static void main(String[] args) throws Exception {
    String username = "bob@google.org";
    String password = "Password1";
    String secretID = "BlahBlahBlah";
    String SALT2 = "deliciously salty";

    // Get the Key
    byte[] key = (SALT2 + username + password).getBytes();
    System.out.println((SALT2 + username + password).getBytes().length);

    // Need to pad key for AES
    // TODO: Best way?

    // Generate the secret key specs.
    SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

    // Instantiate the cipher
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

    byte[] encrypted = cipher.doFinal((secrectID).getBytes());
    System.out.println("encrypted string: " + asHex(encrypted));

    cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
    byte[] original = cipher.doFinal(encrypted);
    String originalString = new String(original);
    System.out.println("Original string: " + originalString + "\nOriginal string (Hex): " + asHex(original));
}

现在,我得到一个异常“无效的AES密钥长度:86个字节”。我需要垫钥匙吗?我该怎么办?

还需要为ECB或CBC设置任何内容吗?

谢谢



16
哈哈,好笑。实际上,我确实有个随机盐,但是我整理了代码以使问题更加清楚。这就是为什么该变量名为SALT2的原因。但是对于遇到相同问题并喜欢复制/粘贴代码的其他人来说,这是一个很好的参考。
伯尼·佩雷斯

Answers:


125

编辑:

如注释中所写,旧代码不是“最佳实践”。您应该使用像PBKDF2这样的密钥生成算法,并且迭代次数很高。您还应该至少部分使用非静态(对于每个“身份”而言是唯一的)盐。如果可能,则随机生成并与密文一起存储。

    SecureRandom sr = SecureRandom.getInstanceStrong();
    byte[] salt = new byte[16];
    sr.nextBytes(salt);

    PBEKeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 1000, 128 * 8);
    SecretKey key = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1").generateSecret(spec);
    Cipher aes = Cipher.getInstance("AES");
    aes.init(Cipher.ENCRYPT_MODE, key);

===========

旧答案

您应该使用SHA-1从密钥生成哈希并将结果修整为128位(16字节)。

另外,不要通过getBytes()从字符串生成字节数组,它使用平台默认的字符集。因此,密码“blaöä”在不同平台上导致不同的字节数组。

byte[] key = (SALT2 + username + password).getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16); // use only first 128 bit

SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

编辑:如果需要256位作为密钥大小,则需要下载“ Java密码学扩展(JCE)无限强度管辖权策略文件” Oracle下载链接,使用SHA-256作为哈希并删除Arrays.copyOf行。“ ECB”是默认密码模式,“ PKCS5Padding”是默认填充。您可以通过Cipher.getInstance使用不同的密码模式和填充模式以下格式字符串:“密码/模式/填充”

对于使用CTS和PKCS5Padding的AES,字符串为:“ AES / CTS / PKCS5Padding”


这将起作用,但是它会哈希我的密码,然后仅使用前几位。有没有更好的方法可以做到这一点?
伯尼·佩雷斯

4
没有更好的方法来生成密钥,因为AES需要128/192/256位密钥。如果您不对密钥进行哈希处理,而仅修整输入,则只会使用前16/24/32字节。因此,生成哈希是唯一合理的方法。
mknjc

13
请注意,此答案未使用良好的密钥派生功能,因此不够安全。有关密钥派生函数的过时信息,请参见其他答案-不幸的是仍然是静态盐。
Maarten Bodewes

2
可能我建议删除此答案,因为这是非常糟糕的做法。应该使用适当的密钥派生功能-至少为PBKDF2。
鲍里斯蜘蛛

1
是的,正如马尔滕几年前所说,答案非常糟糕。请从密码学密钥推导函数中
kelalaka

14

您应该使用KeyGenerator生成密钥,

AES密钥长度为128、192和256位,具体取决于要使用的密码。

这里看看教程

这是基于密码的加密的代码,它具有通过System.in输入的密码,您可以根据需要更改为使用存储的密码。

        PBEKeySpec pbeKeySpec;
        PBEParameterSpec pbeParamSpec;
        SecretKeyFactory keyFac;

        // Salt
        byte[] salt = {
            (byte)0xc7, (byte)0x73, (byte)0x21, (byte)0x8c,
            (byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99
        };

        // Iteration count
        int count = 20;

        // Create PBE parameter set
        pbeParamSpec = new PBEParameterSpec(salt, count);

        // Prompt user for encryption password.
        // Collect user password as char array (using the
        // "readPassword" method from above), and convert
        // it into a SecretKey object, using a PBE key
        // factory.
        System.out.print("Enter encryption password:  ");
        System.out.flush();
        pbeKeySpec = new PBEKeySpec(readPassword(System.in));
        keyFac = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);

        // Create PBE Cipher
        Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");

        // Initialize PBE Cipher with key and parameters
        pbeCipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);

        // Our cleartext
        byte[] cleartext = "This is another example".getBytes();

        // Encrypt the cleartext
        byte[] ciphertext = pbeCipher.doFinal(cleartext);

3
如何使用KeyGenerator用密码生成密钥?我想根据密码生成相同的密钥。所以我以后可以解密该字符串。
伯尼·佩雷斯

您所说的是基于密码的加密而不是AES。我用PBE示例程序更新了答案
Keibosh 2010年

5
尝试使用PBEKDF2密钥生成器,而使用字符串“ PBKDF2WithHmacSHA1”进行SecretKeyFactory更新。
Maarten Bodewes,2013年

12
实际上,此答案中所有使用的加密原语都是过时的,请确保MD5和DES已经过时。谨慎。
Maarten Bodewes

MD5和DES是弱密码套件,应避免使用
atom88

6
import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.*;
import java.io.BufferedReader;
import java.io.FileReader;

public class AESFile 
{
private static String algorithm = "AES";
private static byte[] keyValue=new byte[] {'0','2','3','4','5','6','7','8','9','1','2','3','4','5','6','7'};// your key

    // Performs Encryption
    public static String encrypt(String plainText) throws Exception 
    {
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(algorithm);
            chiper.init(Cipher.ENCRYPT_MODE, key);
            byte[] encVal = chiper.doFinal(plainText.getBytes());
            String encryptedValue = new BASE64Encoder().encode(encVal);
            return encryptedValue;
    }

    // Performs decryption
    public static String decrypt(String encryptedText) throws Exception 
    {
            // generate key 
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(algorithm);
            chiper.init(Cipher.DECRYPT_MODE, key);
            byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedText);
            byte[] decValue = chiper.doFinal(decordedValue);
            String decryptedValue = new String(decValue);
            return decryptedValue;
    }

//generateKey() is used to generate a secret key for AES algorithm
    private static Key generateKey() throws Exception 
    {
            Key key = new SecretKeySpec(keyValue, algorithm);
            return key;
    }

    // performs encryption & decryption 
    public static void main(String[] args) throws Exception 
    {
        FileReader file = new FileReader("C://myprograms//plaintext.txt");
        BufferedReader reader = new BufferedReader(file);
        String text = "";
        String line = reader.readLine();
    while(line!= null)
        {
            text += line;
    line = reader.readLine();
        }
        reader.close();
    System.out.println(text);

            String plainText = text;
            String encryptedText = AESFile.encrypt(plainText);
            String decryptedText = AESFile.decrypt(encryptedText);

            System.out.println("Plain Text : " + plainText);
            System.out.println("Encrypted Text : " + encryptedText);
            System.out.println("Decrypted Text : " + decryptedText);
    }
}

5
也许再添加一些说明文字。
ChrisG 2013年

问题,具有keyValuebyte数组有什么意义?我看到它被用来制作密钥,为什么?可以使用likeSecretKey代替吗?如果是这样,怎么办?
奥斯丁

@Mandrek,文件“ plaintext.txt”的内容将被加密。上面的逻辑对文件中的数据/消息进行加密,该文件在FileReader构造函数中作为参数读取。
沙卡·默西

2

这将工作。

public class CryptoUtils {

    private  final String TRANSFORMATION = "AES";
    private  final String encodekey = "1234543444555666";
    public  String encrypt(String inputFile)
            throws CryptoException {
        return doEncrypt(encodekey, inputFile);
    }


    public  String decrypt(String input)
            throws CryptoException {
    // return  doCrypto(Cipher.DECRYPT_MODE, key, inputFile);
    return doDecrypt(encodekey,input);
    }

    private  String doEncrypt(String encodekey, String inputStr)   throws CryptoException {
        try {

            Cipher cipher = Cipher.getInstance(TRANSFORMATION);

            byte[] key = encodekey.getBytes("UTF-8");
            MessageDigest sha = MessageDigest.getInstance("SHA-1");
            key = sha.digest(key);
            key = Arrays.copyOf(key, 16); // use only first 128 bit

            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

            byte[] inputBytes = inputStr.getBytes();     
            byte[] outputBytes = cipher.doFinal(inputBytes);

            return Base64Utils.encodeToString(outputBytes);

        } catch (NoSuchPaddingException | NoSuchAlgorithmException
                | InvalidKeyException | BadPaddingException
                | IllegalBlockSizeException | IOException ex) {
            throw new CryptoException("Error encrypting/decrypting file", ex);
       }
     }


    public  String doDecrypt(String encodekey,String encrptedStr) { 
          try {     

              Cipher dcipher = Cipher.getInstance(TRANSFORMATION);
              dcipher = Cipher.getInstance("AES");
              byte[] key = encodekey.getBytes("UTF-8");
              MessageDigest sha = MessageDigest.getInstance("SHA-1");
              key = sha.digest(key);
              key = Arrays.copyOf(key, 16); // use only first 128 bit

              SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

              dcipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
            // decode with base64 to get bytes

              byte[] dec = Base64Utils.decode(encrptedStr.getBytes());  
              byte[] utf8 = dcipher.doFinal(dec);

              // create new string based on the specified charset
              return new String(utf8, "UTF8");

          } catch (Exception e) {

            e.printStackTrace();

          }
      return null;
      }
 }

2

MD5,AES,无填充

import static javax.crypto.Cipher.DECRYPT_MODE;
import static javax.crypto.Cipher.ENCRYPT_MODE;
import static org.apache.commons.io.Charsets.UTF_8;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

public class PasswordUtils {

    private PasswordUtils() {}

    public static String encrypt(String text, String pass) {
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            Key key = new SecretKeySpec(messageDigest.digest(pass.getBytes(UTF_8)), "AES");
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(ENCRYPT_MODE, key);

            byte[] encrypted = cipher.doFinal(text.getBytes(UTF_8));
            byte[] encoded = Base64.getEncoder().encode(encrypted);
            return new String(encoded, UTF_8);

        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
            throw new RuntimeException("Cannot encrypt", e);
        }
    }

    public static String decrypt(String text, String pass) {
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            Key key = new SecretKeySpec(messageDigest.digest(pass.getBytes(UTF_8)), "AES");
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(DECRYPT_MODE, key);

            byte[] decoded = Base64.getDecoder().decode(text.getBytes(UTF_8));
            byte[] decrypted = cipher.doFinal(decoded);
            return new String(decrypted, UTF_8);

        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
            throw new RuntimeException("Cannot decrypt", e);
        }
    }
}

如何在角度(离子4)中创建像SecretKeySpec这样的安全密钥;
Nitin Karale

0
    byte[] seed = (SALT2 + username + password).getBytes();
    SecureRandom random = new SecureRandom(seed);
    KeyGenerator generator;
    generator = KeyGenerator.getInstance("AES");
    generator.init(random);
    generator.init(256);
    Key keyObj = generator.generateKey();
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