Question

我自己实现了rc4算法，就像加密和解密文本的魅力一样，当我尝试加密/解密图像时出现问题。我的输出图像始终不可读。没有异常被抛出。我不确定它的加密或解密是否有效，或者两者兼而有之。我们将非常感谢您的帮助。

RC4 Class

公共类RC4 {

private byte[] S = new byte[256];

public RC4 (byte[] key) {

     byte[] T = new byte[256];

    int keylen, j;
    byte t;

    for (int i = 0; i < 256; i++) {

        keylen = key.length;
        S[i] = (byte) i;
        T[i] = key[i % keylen];
    }

    //KSA -  key-scheduling algorithm is used to initialize the permutation in the array "S"
    j = 0;
    for (int i = 0 ; i < 256 ; i++)
    {
        j = ((j + S[i] + T[i]) % 256) & 0xFF;

        //swap
        t = S[i];
        S[i] = S[j];
        S[j] = t;
    }
}

public byte[] encrypt(byte[] plaintext)
{
    int j = 0, i = 0, t, k;
    byte temp;
    byte[] pt,ct, s;

    //deep copy
    s = S.clone();

    pt = plaintext;
    ct = new byte[pt.length];
    for (int jj = 0 ; jj < pt.length; jj++)
    {
        i = ((i + 1) % 256) & 0xFF;
        j = ((j + s[i]) % 256) & 0xFF;

        //classic swap
        temp    = s[jj];
        s[jj]   = s[j];
        s[j]    = temp;

        t = ((s[i] + s[j]) % 256) & 0xFF;

        k = s[t];

        ct[jj] = (byte) (k ^ pt[jj]);
    }
    return ct;
}

public byte[] decrypt(byte[] ciphertext)
{
    return encrypt(ciphertext);
}

}

然后我的电话：服务器端

Bitmap SelectedImage = BitmapFactory.decodeFile(selectedImagePath);
            byte[] b = bitmapToByteArray(SelectedImage);

            RC4 rc4 = new RC4(sharedSecret);
            byte[] encrypted = rc4.encrypt(b);
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
            objectOutputStream.writeObject(encrypted);
            objectOutputStream.flush();

客户端

FileOutputStream fos = null;
ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());
                byte[] b = (byte[])objectInputStream.readObject();

                RC4 rc4 = new RC4(sharedSecret);
                byte[] decrypted = rc4.decrypt(b);

                Bitmap bmp = BitmapFactory.decodeByteArray(decrypted, 0, decrypted.length);
                fos = new FileOutputStream(file);
                bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
                fos.close();

Answer 1

我发现了我的错误，它在加密功能中;滥用柜台。以下是更正后的代码。

for (int counter = 0 ; counter < pt.length; counter++)
    {
        i = ((i + 1) % 256) & 0xFF;
        j = ((j + s[i]) % 256) & 0xFF;

        //classic swap
        temp    = s[j];
        s[j]    = s[i];
        s[i]    = temp;

        t = ((s[i] + s[j]) % 256) & 0xFF;

        k = s[t];

        ct[counter] = (byte) (k ^ pt[counter]);

在android

1 个答案: