从字符串生成密钥？ [英] Generate Key from string?

问题描述

我需要从字符串生成一个Key，这样我总是可以从同一个字符串创建相同的键。 （特别是一个Key对象，这样我就可以用它来创建一个Cipher来创建一个SealedObject）

I need to generate a Key from a string, such that I can always create the same key from the same string. (Specifically a Key object, so that I can use it to create a Cipher in turn to create a SealedObject)

这在Java中是否可行，以及哪个类/方法组合我应该这样做吗？

Is this possible in Java, and what class/method combination should I be looking at to do so?

推荐答案

对于AES加密：

SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);

byte[] iv = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
byte[] ciphertext = cipher.doFinal("Hello, World!".getBytes("UTF-8"));

// reinit cypher using param spec
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));

同样适用于与旧系统通信的已弃用的PBKDF1和不安全的DES 学习目的：

Similarly for the deprecated PBKDF1 and insecure DES for communicating with legacy systems or learning purposes:

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

int count = 20;

PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, count);
PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());
SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);

Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);

SealedObject sealed = new SealedObject(object, cipher);
...

请注意，迭代计数在上一个示例中也太低了。

Note that the iteration count is too low as well in the last example.

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