Code:
public class RC4
{
public static byte[] Encrypt(byte[] pwd, byte[] data)
{
int a, i, j, k, tmp;
int[] key, box;
byte[] cipher;
key = new int[256];
box = new int[256];
cipher = new byte[data.Length];
for (i = 0; i < 256; i++)
{
key[i] = pwd[i % pwd.Length];
box[i] = i;
}
for (j = i = 0; i < 256; i++)
{
j = (j + box[i] + key[i]) % 256;
tmp = box[i];
box[i] = box[j];
box[j] = tmp;
}
for (a = j = i = 0; i < data.Length; i++)
{
a++;
a %= 256;
j += box[a];
j %= 256;
tmp = box[a];
box[a] = box[j];
box[j] = tmp;
k = box[((box[a] + box[j]) % 256)];
cipher[i] = (byte)(data[i] ^ k);
}
return cipher;
}
public static byte[] Decrypt(byte[] pwd, byte[] data)
{
return Encrypt(pwd, data);
}
}