Re: [Vala] RC4 encryption algorithm

[pancake <pancake youterm com>]

I stopped reading when I saw you are swapping the S box with integers instead of unsigned chars.

I have googled "rc4" for you from my phone and found two results in the first page that may give you some 
light..

http://forum.intern0t.net/c-c/783-rc4-algorithm.html
http://www.cypherspace.org/rsa/rc4c.html

On 27/10/2011, at 22:29, "Luis L. Rodríguez Oro" <luisr uci cu> wrote:

> hello, I have some problem with RC4 encryption algorithm. I don't know in what point the algorithm be come 
> asymmetric.
>
> Please, help me.
>
> string rc4_encrypt(string key, string text) {
>    int S[255];
>    int i;
>    int len = key.length;
>    int j = 0;
>    int temp;
>
>    for (i = 0; i < 255; i++)
>        S[i] = i;
>
>    for (i = 0; i < 255; i++) {
>    int s = (int) key[i % len]; //ascii
>
>    j = (j + S[i] + s) % 256;
>        temp = S[i];
>    S[i] = S[j];
>    S[j] = temp;
>    }
>
>    i = j = 0;
>    string conv="";
>    for (var y = text; y.get_char () != 0; y = y.next_char ()) {
>    int ansi = (int) y.get_char ();
>
>    i = (i + 1) % 256;
>    j = (j + S[i]) % 256;
>
>    temp = S[i];
>    S[i] = S[j];
>    S[j] = temp;
>
>    temp = ansi ^ S[(S[i] + S[j]) % 256];
>    var cara = (char) temp;
>
>    conv += cara.to_string();
>    }
>    return conv;
> }
>
>
> string rc4_decrypt(string key, string text) {
>    return rc4_encrypt(key, text);
> }
>
> void main() {
>    string encr = rc4_encrypt("Key", "Plaintext");
>    string decr = rc4_decrypt("Key", encr);
>
>    // the big problem is HERE!
>    if (decr != "Plaintext")
>       warning("do not work decrypt");
> }
>
>
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