java - Java中的基本加密算法无法解密

Question

我正在尝试在 Java 中实现 TEA(微型加密算法)，以对包含大小为 512 的音频的 byte[] 进行编码。

这是我的加密函数:

//Encrypt 64bit/8byte buffer with 128bit/16byte key
public byte[] encrypt(int[] data, int[] key) { 
    int x = data[0]; 
    int y = data[1]; 
    ByteBuffer encrypted = ByteBuffer.allocate(8);
    int sum = 0; 
    int constant = 0x9e3779b9; //magic constant

    for (int k = 0; k < 32; ++k) { 
        sum += constant; 
        x += (y << 4 & 0xfffffff0) + key[0] ^ y + sum ^ (y >> 5 & 0x7ffffff) + key[1]; 
        y += (x << 4 & 0xfffffff0) + key[2] ^ x + sum ^ (x >> 5 & 0x7ffffff) + key[3]; 
    }
    encrypted.putInt(x);
    encrypted.putInt(y);
    return encrypted.array();
}

并解密:

public byte[] decrypt(int[] data, int[] key) { 
    int x = data[0]; 
    int y = data[1]; 
    ByteBuffer decrypted = ByteBuffer.allocate(8);
    int sum = 0xC6EF3720; //32*delta
    int constant = 0x9e3779b9; //magic constant

    for (int k = 0; k < 32; ++k) { 
        x -= (x << 4 & 0xfffffff0) + key[2] ^ x + sum ^ (x >> 5 & 0x7ffffff) + key[3]; 
        y -= (y << 4 & 0xfffffff0) + key[0] ^ y + sum ^ (y >> 5 & 0x7ffffff) + key[1]; 
        sum -= constant; 
    }
    decrypted.putInt(x); 
    decrypted.putInt(y);
    return decrypted.array();
}

和我的加密调用:

ByteBuffer unwrapEncrypt = ByteBuffer.allocate(512);
int[] encryptionKey = {55555, 8888, 123857, 912029};

//block is a byte[] with length 512
ByteBuffer plainText = ByteBuffer.wrap(block);
for (int j = 0; j < block.length / 8; j++) {
    //Initiate array for int pairs
    int[] plainTextInts = new int[2];
    plainTextInts[0] = plainText.getInt();
    plainTextInts[1] = plainText.getInt();
    //Encrypt and store
    unwrapEncrypt.put(encrypt(plainTextInts, encryptionKey));
}

并解密调用:

ByteBuffer audioToPlay = ByteBuffer.allocate(512);
int[] decryptionKey = {55555, 8888, 123857, 912029};

//audio is a byte[] with length 512
ByteBuffer cipherText = ByteBuffer.wrap(audio);
for (int j = 0; j < audio.length / 8; j++) {
    int[] plainTextInts = new int[2];
    //Initiate array for int pairs
    plainTextInts[0] = cipherText.getInt();
    plainTextInts[1] = cipherText.getInt();
    //Decrypt and store
    audioToPlay.put(decrypt(plainTextInts, decryptionKey));
}

对大量代码感到抱歉 - 我已经尝试分析发送的音频和接收到的解密数据 - 它们的长度都是正确的，只是完全不同。如果我删除这 4 个代码块，音频就完美了。有人能发现发生了什么吗？谢谢

Answer 1

与 Wikipedia' s description of TEA 进行比较时，您的 decrpyt() 方法似乎存在错误。 。您必须交换 -= 运算符左侧的 x 和 y。以下似乎对我有用:

public byte[] decrypt(int[] data, int[] key) { 
    int x = data[0]; 
    int y = data[1]; 
    ByteBuffer decrypted = ByteBuffer.allocate(8);
    int sum = 0xC6EF3720; //32*delta
    int constant = 0x9e3779b9; //magic constant

    for (int k = 0; k < 32; ++k) { 
        y -= (x << 4 & 0xfffffff0) + key[2] ^ x + sum ^ (x >> 5 & 0x7ffffff) + key[3]; 
        x -= (y << 4 & 0xfffffff0) + key[0] ^ y + sum ^ (y >> 5 & 0x7ffffff) + key[1]; 
        sum -= constant; 
    }
    decrypted.putInt(x); 
    decrypted.putInt(y);
    return decrypted.array();
}