我正在尝试用Java实现TEA(微加密算法)来编码包含大小为512的音频的byte[]
。
这是我的加密功能:
//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();
}
和我的加密电话:
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));
}
和解密电话:
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));
}
很抱歉代码很多 - 我已经尝试过分析发送的音频并收到解密数据 - 它们都是正确的长度,完全不同。如果我删除这4个代码块,音频是完美的。有谁能发现什么了?谢谢
我将decrpyt()
方法与Wikipedia' s description of TEA进行比较时似乎有一个错误。你必须在-=
运算符的左边交换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();
}