use nettle_sys::{
cast128_ctx, nettle_cast128_decrypt, nettle_cast128_encrypt,
nettle_cast5_set_key,
};
use std::cmp::min;
use std::mem::{MaybeUninit, transmute};
use std::os::raw::c_void;
use crate::cipher::RawCipherFunctionPointer;
use crate::{cipher::Cipher, Result};
pub struct Cast128 {
context: Box<cast128_ctx>,
}
impl_zeroing_drop_for!(Cast128);
impl Cast128 {
pub fn with_key(key: &[u8]) -> Self {
let context = unsafe {
let mut ctx = Box::new(MaybeUninit::uninit());
nettle_cast5_set_key(ctx.as_mut_ptr(), key.len(), key.as_ptr());
transmute(ctx)
};
Cast128 { context }
}
}
impl Cipher for Cast128 {
const BLOCK_SIZE: usize = ::nettle_sys::CAST128_BLOCK_SIZE as usize;
const KEY_SIZE: usize = ::nettle_sys::CAST5_MAX_KEY_SIZE as usize;
fn with_encrypt_key(key: &[u8]) -> Result<Cast128> {
Ok(Cast128::with_key(key))
}
fn with_decrypt_key(key: &[u8]) -> Result<Cast128> {
Ok(Cast128::with_key(key))
}
fn encrypt(&mut self, dst: &mut [u8], src: &[u8]) {
unsafe {
nettle_cast128_encrypt(
self.context.as_mut() as *mut _,
min(src.len(), dst.len()),
dst.as_mut_ptr(),
src.as_ptr(),
)
};
}
fn decrypt(&mut self, dst: &mut [u8], src: &[u8]) {
unsafe {
nettle_cast128_decrypt(
self.context.as_mut() as *mut _,
min(src.len(), dst.len()),
dst.as_mut_ptr(),
src.as_ptr(),
)
};
}
fn context(&mut self) -> *mut c_void {
(self.context.as_mut() as *mut cast128_ctx) as *mut c_void
}
fn raw_encrypt_function() -> RawCipherFunctionPointer {
RawCipherFunctionPointer::new(nettle_cast128_encrypt)
}
fn raw_decrypt_function() -> RawCipherFunctionPointer {
RawCipherFunctionPointer::new(nettle_cast128_decrypt)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn set_key() {
let key = &(b"\x01\x02\x03\x04\x05\x06\x07\x08"[..]);
let _ = Cast128::with_encrypt_key(key).unwrap();
let _ = Cast128::with_decrypt_key(key).unwrap();
}
#[test]
fn round_trip() {
let key = vec![0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08];
let input = vec![
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10, 0x11,
0x12, 0x13, 0x14, 0x15, 0x16,
];
let mut cipher = vec![0; 16];
let mut output = vec![0; 16];
let mut enc = Cast128::with_encrypt_key(&key).unwrap();
let mut dec = Cast128::with_decrypt_key(&key).unwrap();
enc.encrypt(&mut cipher, &input);
dec.decrypt(&mut output, &cipher);
assert_eq!(output, input);
}
}