使用充气城堡在Java中加密xml文件的示例

Question

任何人都可以向我展示（或提供指向）如何使用充气城堡在Java中加密文件的示例吗？我查看了bouncycastle.org，但找不到其API的任何文档。即使只是知道要使用哪些类，也对我入门很有帮助！

Answer 1

您要执行哪种类型的加密？基于密码（PBE），对称，不对称？这就是您配置Cipher的全部方法。

您不必使用任何BouncyCastle特定的API，只需使用它提供的算法即可。这是一个使用BouncyCastle PBE密码加密字符串的示例：

import java.security.SecureRandom;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

public class PBE {

    private static final String salt = "A long, but constant phrase that will be used each time as the salt.";
    private static final int iterations = 2000;
    private static final int keyLength = 256;
    private static final SecureRandom random = new SecureRandom();

    public static void main(String [] args) throws Exception {
        Security.insertProviderAt(new BouncyCastleProvider(), 1);

        String passphrase = "The quick brown fox jumped over the lazy brown dog";
        String plaintext = "hello world";
        byte [] ciphertext = encrypt(passphrase, plaintext);
        String recoveredPlaintext = decrypt(passphrase, ciphertext);

        System.out.println(recoveredPlaintext);
    }

    private static byte [] encrypt(String passphrase, String plaintext) throws Exception {
        SecretKey key = generateKey(passphrase);

        Cipher cipher = Cipher.getInstance("AES/CTR/NOPADDING");
        cipher.init(Cipher.ENCRYPT_MODE, key, generateIV(cipher), random);
        return cipher.doFinal(plaintext.getBytes());
    }

    private static String decrypt(String passphrase, byte [] ciphertext) throws Exception {
        SecretKey key = generateKey(passphrase);

        Cipher cipher = Cipher.getInstance("AES/CTR/NOPADDING");
        cipher.init(Cipher.DECRYPT_MODE, key, generateIV(cipher), random);
        return new String(cipher.doFinal(ciphertext));
    }

    private static SecretKey generateKey(String passphrase) throws Exception {
        PBEKeySpec keySpec = new PBEKeySpec(passphrase.toCharArray(), salt.getBytes(), iterations, keyLength);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWITHSHA256AND256BITAES-CBC-BC");
        return keyFactory.generateSecret(keySpec);
    }

    private static IvParameterSpec generateIV(Cipher cipher) throws Exception {
        byte [] ivBytes = new byte[cipher.getBlockSize()];
        random.nextBytes(ivBytes);
        return new IvParameterSpec(ivBytes);
    }

}