java - DES加密:给定的最终块未正确填充

我得到了这段代码：

static ReadableByteChannel readChannel = null;
static WritableByteChannel writeChannel = null;
static SecretKey key = makeKeyFromPassword("chuj".getBytes());

public static SecretKey makeKeyFromPassword(byte[] password) {

    try {
        key = KeyGenerator.getInstance("DES").generateKey();
        byte[] encoded = key.getEncoded();
        return new SecretKeySpec(encoded, "DES");
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return null;
}

public static void run(int mode) throws Exception {
    ByteBuffer readBuffer = ByteBuffer.allocate(1024);
    ByteBuffer writeBuffer = ByteBuffer.allocate(1024);

    //initializing cipher...
    Cipher cipher = javax.crypto.Cipher.getInstance("DES");
    cipher.init(mode, key);

    int read = -1;
    while((read = readChannel.read(readBuffer)) != -1){
        readBuffer.flip();
        cipher.doFinal(readBuffer, writeBuffer);
        writeChannel.write(writeBuffer);
        readBuffer.clear();
        writeBuffer.clear();
    }
}

public static void main(String[] args) {
    // TODO Auto-generated method stub\
    FileOutputStream fos = null;
    String inFileString = "C:\\test.txt"; // Valid file pathname
    String fileString = "C:\\des.txt"; // Valid file pathname
    int mode = Cipher.ENCRYPT_MODE;
    FileSystem fs = FileSystems.getDefault();
    Path fp = fs.getPath(inFileString);

    try {
        readChannel = FileChannel.open(fp, EnumSet.of(StandardOpenOption.READ));
        fos = new FileOutputStream(fileString);
        writeChannel = Channels.newChannel(fos);
        run(mode);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

加密无例外。
但是当我尝试解密数据时（模式== DECRYPT_MODE并切换文件名）

javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:811)
at com.sun.crypto.provider.DESCipher.engineDoFinal(DESCipher.java:357)
at javax.crypto.CipherSpi.bufferCrypt(CipherSpi.java:767)
at javax.crypto.CipherSpi.engineDoFinal(CipherSpi.java:721)
at javax.crypto.Cipher.doFinal(Cipher.java:2382)
at Test.run(Test.java:57)
at Test.main(Test.java:77)

弹出。

我尝试使用不同的键，但未成功。
任何帮助将不胜感激。
[我必须使用通道，此代码仅测试较大类的一部分]

最佳答案

两件事情：


首先，在password方法中与makeKeyFromPassword变量没有关联。返回的SecretKey是随机的，因此不可能在程序的两个单独运行中对数据进行解码。
其次，在writeBuffer.flip()之后应该有cipher.doFinal(readBuffer, writeBuffer) ;-)


工作代码（请注意，用于生成DES密钥的密码必须至少为8个字符）：

public class Test {

    static ReadableByteChannel readChannel = null;
    static WritableByteChannel writeChannel = null;
    static SecretKey key = makeKeyFromPassword("abcdefghi".getBytes());
    static byte b[];

    public static SecretKey makeKeyFromPassword(byte[] password) {
        try {
            DESKeySpec dks = new DESKeySpec(password);
            SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
            return skf.generateSecret(dks);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void run(int mode) throws Exception {
        ByteBuffer readBuffer = ByteBuffer.allocate(1024);
        ByteBuffer writeBuffer = ByteBuffer.allocate(1024);

        // initializing cipher...
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(mode, key);

        while (readChannel.read(readBuffer) != -1) {
            readBuffer.flip();
            cipher.doFinal(readBuffer, writeBuffer);
            writeBuffer.flip();
            writeChannel.write(writeBuffer);
            readBuffer.clear();
            writeBuffer.clear();
        }
    }

    static void f(String inFileString, String fileString, int mode) {
        FileOutputStream fos = null;
        FileSystem fs = FileSystems.getDefault();
        Path fp = fs.getPath(inFileString);

        try {
            readChannel = FileChannel.open(fp,
                    EnumSet.of(StandardOpenOption.READ));
            fos = new FileOutputStream(fileString);
            writeChannel = Channels.newChannel(fos);
            run(mode);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        f("C:\\test.txt", "C:\\des.txt", Cipher.ENCRYPT_MODE);
        System.out.println("Encrypted.");
        f("C:\\des.txt", "C:\\undes.txt", Cipher.DECRYPT_MODE);
        System.out.println("Decrypted.");
    }

}

关于java - DES加密:给定的最终块未正确填充，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20060200/