java - 需要帮助实现 CipherInputStream 和 CipherOutputStream

Question

这个问题已经有答案了:

Initial bytes incorrect after Java AES/CBC decryption (10 个回答)

已关闭 4 年前。

我在将 FileInputStream 和 FileOutputStream 转换为 3DES 加密算法的 CipherInputStream 和 CipherOutputStream 时遇到一些问题。有人可以指导我走上正确的道路吗？我最终收到错误:“CipherInputStream 无法解析为类型”。抱歉，如果这是显而易见的。

// author Alexander Matheakis
public static void main(String[] args) throws Exception {


    // file to be encrypted
    FileInputStream inputFile = new FileInputStream("plainfile.txt");

    // encrypted file
    FileOutputStream outputFile = new FileOutputStream("C:\\Users\\islan\\OneDrive\\Documents\\Encryptor\\plainfile.des");

    // password to encrypt the file
    String passKey = "tkfhkggovubm";


    byte[] salt = new byte[8];
    SecureRandom r = new SecureRandom();    
    r.nextBytes(salt);
    PBEKeySpec pbeKeySpec = new PBEKeySpec(passKey.toCharArray());
    SecretKeyFactory secretKeyFactory = SecretKeyFactory
            .getInstance("PBEWithSHA1AndDESede");
    SecretKey secretKey = secretKeyFactory.generateSecret(pbeKeySpec);


    PBEParameterSpec pbeParameterSpec = new PBEParameterSpec(salt, 99999);
    Cipher cipher = Cipher.getInstance("PBEWithSHA1AndDESede"); 
    cipher.init(Cipher.ENCRYPT_MODE, secretKey, pbeParameterSpec);
    outputFile.write(salt);

    byte[] input = new byte[64];
    int bytesRead;
    while ((bytesRead = inputFile.read(input)) != -1) {
        byte[] output = cipher.update(input, 0, bytesRead);
        if (output != null)
            outputFile.write(output);
    }

    byte[] output = cipher.doFinal();
    if (output != null)
        outputFile.write(output);

    inputFile.close();
    outputFile.flush();
    outputFile.close();

// author Alexander Matheakis

Answer 1

这对我有用:

public class Cypher {

    // password to encrypt the file
    private static final String passKey = "tkfhkggovubm";

    public static void main(String[] args) throws Exception {

        try (FileInputStream inputFile = new FileInputStream("plainfile.txt");
                FileOutputStream outputFile = new FileOutputStream("plainfile.des");) {

            byte[] salt = new byte[8];
            SecureRandom r = new SecureRandom();
            r.nextBytes(salt);

            outputFile.write(salt);

            PBEKeySpec pbeKeySpec = new PBEKeySpec(passKey.toCharArray());
            SecretKeyFactory secretKeyFactory = SecretKeyFactory
                    .getInstance("PBEWithSHA1AndDESede");
            SecretKey secretKey = secretKeyFactory.generateSecret(pbeKeySpec);

            PBEParameterSpec pbeParameterSpec = new PBEParameterSpec(salt, 99999);
            Cipher cipher = Cipher.getInstance("PBEWithSHA1AndDESede");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey, pbeParameterSpec);

            try (CipherOutputStream cis = new CipherOutputStream(outputFile, cipher);) {
                IOUtils.copy(inputFile, cis);
            }
        }

        try (FileInputStream fis = new FileInputStream("plainfile.des");
                FileOutputStream outputFile = new FileOutputStream("plainfile.txt2");) {
            byte[] salt = new byte[8];
            int saltBytes = fis.read(salt);
            if (saltBytes!=salt.length)
                throw new Exception("Huh???");

            PBEKeySpec pbeKeySpec = new PBEKeySpec(passKey.toCharArray());
            SecretKeyFactory secretKeyFactory = SecretKeyFactory
                    .getInstance("PBEWithSHA1AndDESede");
            SecretKey secretKey = secretKeyFactory.generateSecret(pbeKeySpec);

            PBEParameterSpec pbeParameterSpec = new PBEParameterSpec(salt, 99999);
            Cipher cipher = Cipher.getInstance("PBEWithSHA1AndDESede");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, pbeParameterSpec);

            try (CipherInputStream cis = new CipherInputStream(fis, cipher);) {
                IOUtils.copy(cis, outputFile);
            }
        }
    }
}

执行main后，plainfile.txt和plainfile.txt2是相等的。 plainfile.des 已加密。

IOUtils.copy 是 apache.commons-io 中的一个方法，它在内部保留一个缓冲区并将所有字节从一个流写入另一个流。它只是将 byte[] input = ... 提取到方法中，并使用 try-with-resources 。这使代码变得简单并具有更好的可读性。