AM2R-Community-Updates/scripts/rc4.gml

/// rc4()
// https://en.wikipedia.org/wiki/RC4
var str, key, out, len, i, S, j, temp, pos, t;
str = argument0;
key = argument1;
out = "";
len = string_length(key);
for (i = 0; i < 256; i += 1) {
    S[i] = i;
}
j = 0;
for (i = 0; i < 256; i += 1) {
    j = (j + S[i] + ord(string_char_at(key, i % len + 1))) % 256;
    temp = S[i];
    S[i] = S[j];
    S[j] = temp;
}
i = 0;
j = 0;
for (pos = 0; pos < string_length(str); pos += 1) {
    i = (i + 1) % 256;
    j = (j + S[i]) % 256;
    temp = S[i];
    S[i] = S[j];
    S[j] = temp;
    t = (S[i] + S[j]) % 256;
    out += chr(ord(string_char_at(str, pos + 1)) ^ S[t]);
}
return out;