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use buffer::{BufferResult, RefReadBuffer, RefWriteBuffer};
use symmetriccipher::{Encryptor, Decryptor, SynchronousStreamCipher, SymmetricCipherError};
use cryptoutil::symm_enc_or_dec;
#[derive(Copy)]
pub struct Rc4 {
i: u8,
j: u8,
state: [u8; 256]
}
impl Clone for Rc4 { fn clone(&self) -> Rc4 { *self } }
impl Rc4 {
pub fn new(key: &[u8]) -> Rc4 {
assert!(key.len() >= 1 && key.len() <= 256);
let mut rc4 = Rc4 { i: 0, j: 0, state: [0; 256] };
for (i, x) in rc4.state.iter_mut().enumerate() {
*x = i as u8;
}
let mut j: u8 = 0;
for i in 0..256 {
j = j.wrapping_add(rc4.state[i]).wrapping_add(key[i % key.len()]);
rc4.state.swap(i, j as usize);
}
rc4
}
fn next(&mut self) -> u8 {
self.i = self.i.wrapping_add(1);
self.j = self.j.wrapping_add(self.state[self.i as usize]);
self.state.swap(self.i as usize, self.j as usize);
let k = self.state[(self.state[self.i as usize].wrapping_add(self.state[self.j as usize])) as usize];
k
}
}
impl SynchronousStreamCipher for Rc4 {
fn process(&mut self, input: &[u8], output: &mut [u8]) {
assert!(input.len() == output.len());
for (x, y) in input.iter().zip(output.iter_mut()) {
*y = *x ^ self.next();
}
}
}
impl Encryptor for Rc4 {
fn encrypt(&mut self, input: &mut RefReadBuffer, output: &mut RefWriteBuffer, _: bool)
-> Result<BufferResult, SymmetricCipherError> {
symm_enc_or_dec(self, input, output)
}
}
impl Decryptor for Rc4 {
fn decrypt(&mut self, input: &mut RefReadBuffer, output: &mut RefWriteBuffer, _: bool)
-> Result<BufferResult, SymmetricCipherError> {
symm_enc_or_dec(self, input, output)
}
}
#[cfg(test)]
mod test {
use std::iter::repeat;
use symmetriccipher::SynchronousStreamCipher;
use rc4::Rc4;
struct Test {
key: &'static str,
input: &'static str,
output: Vec<u8>
}
fn tests() -> Vec<Test> {
vec![
Test {
key: "Key",
input: "Plaintext",
output: vec![0xBB, 0xF3, 0x16, 0xE8, 0xD9, 0x40, 0xAF, 0x0A, 0xD3]
},
Test {
key: "Wiki",
input: "pedia",
output: vec![0x10, 0x21, 0xBF, 0x04, 0x20]
},
Test {
key: "Secret",
input: "Attack at dawn",
output: vec![0x45, 0xA0, 0x1F, 0x64, 0x5F, 0xC3, 0x5B,
0x38, 0x35, 0x52, 0x54, 0x4B, 0x9B, 0xF5]
}
]
}
#[test]
fn wikipedia_tests() {
let tests = tests();
for t in tests.iter() {
let mut rc4 = Rc4::new(t.key.as_bytes());
let mut result: Vec<u8> = repeat(0).take(t.output.len()).collect();
rc4.process(t.input.as_bytes(), &mut result);
assert!(result == t.output);
}
}
}
#[cfg(all(test, feature = "with-bench"))]
mod bench {
use test::Bencher;
use symmetriccipher::SynchronousStreamCipher;
use rc4::Rc4;
#[bench]
pub fn rc4_10(bh: & mut Bencher) {
let mut rc4 = Rc4::new("key".as_bytes());
let input = [1u8; 10];
let mut output = [0u8; 10];
bh.iter( || {
rc4.process(&input, &mut output);
});
bh.bytes = input.len() as u64;
}
#[bench]
pub fn rc4_1k(bh: & mut Bencher) {
let mut rc4 = Rc4::new("key".as_bytes());
let input = [1u8; 1024];
let mut output = [0u8; 1024];
bh.iter( || {
rc4.process(&input, &mut output);
});
bh.bytes = input.len() as u64;
}
#[bench]
pub fn rc4_64k(bh: & mut Bencher) {
let mut rc4 = Rc4::new("key".as_bytes());
let input = [1u8; 65536];
let mut output = [0u8; 65536];
bh.iter( || {
rc4.process(&input, &mut output);
});
bh.bytes = input.len() as u64;
}
}