nettle 3.0.0

Rust bindings for the Nettle cryptographic library
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use nettle_sys::{
    arctwo_ctx,
    nettle_arctwo_set_key,
    nettle_arctwo_set_key_ekb,
    nettle_arctwo_encrypt,
    nettle_arctwo_decrypt,
};
use std::mem::zeroed;
use std::os::raw::c_void;
use std::cmp::min;
use Cipher;
use Result;
use cipher::RawCipherFunctionPointer;

/// Ron Rivest's RC2 block cipher defined RFC 2268.
/// # Note
/// RC2 is no longer considered a secure cipher. Only use it for legacy applications.
pub struct ArcTwo {
    context: arctwo_ctx,
}

impl ArcTwo {
    /// Creates a new instance with `key` that can be used for both encryption and decryption.
    pub fn with_key(key: &[u8]) -> Self {
        let mut ctx = unsafe { zeroed() };
        unsafe { nettle_arctwo_set_key(&mut ctx as *mut _, key.len(), key.as_ptr()); }

        ArcTwo{ context: ctx }
    }

    /// Creates a new instance with `key` that can be used for both encryption and decryption. The
    /// `ekb` parameter can be used to limit the effective key size to `ekb` bits. A value of `0`
    /// is handled as `1024`.
    pub fn with_key_ekb(key: &[u8], ekb: u32) -> Self {
        let mut ctx = unsafe { zeroed() };
        unsafe { nettle_arctwo_set_key_ekb(&mut ctx as *mut _, key.len(), key.as_ptr(), ekb); }

        ArcTwo{ context: ctx }
    }
}

impl Cipher for ArcTwo {
    const BLOCK_SIZE: usize = 8;
    const KEY_SIZE: usize = ::nettle_sys::ARCTWO_MAX_KEY_SIZE as usize;

    fn with_encrypt_key(key: &[u8]) -> Result<ArcTwo> {
        Ok(ArcTwo::with_key(key))
    }

    fn with_decrypt_key(key: &[u8]) -> Result<ArcTwo> {
        Ok(ArcTwo::with_key(key))
    }

    fn encrypt(&mut self, dst: &mut [u8], src: &[u8]) {
        unsafe {
            nettle_arctwo_encrypt(
                &mut self.context 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_arctwo_decrypt(
                &mut self.context as *mut _,
                min(src.len(), dst.len()),
                dst.as_mut_ptr(), src.as_ptr())
        };
    }

    fn context(&mut self) -> *mut c_void {
        ((&mut self.context) as *mut arctwo_ctx) as *mut c_void
    }

    fn raw_encrypt_function() -> RawCipherFunctionPointer {
        RawCipherFunctionPointer::new(nettle_arctwo_encrypt)
    }

    fn raw_decrypt_function() -> RawCipherFunctionPointer {
        RawCipherFunctionPointer::new(nettle_arctwo_decrypt)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn set_key() {
        let key = &(b"\x01\x02\x03\x04\x05\x06\x07\x08"[..]);
        let _ = ArcTwo::with_encrypt_key(key).unwrap();
        let _ = ArcTwo::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 = ArcTwo::with_encrypt_key(&key).unwrap();
        let mut dec = ArcTwo::with_decrypt_key(&key).unwrap();

        enc.encrypt(&mut cipher,&input);
        dec.decrypt(&mut output,&cipher);

        assert_eq!(output, input);
    }

    #[test]
    fn round_trip_ekb() {
        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 = ArcTwo::with_key_ekb(&key,42);
        let mut dec = ArcTwo::with_key_ekb(&key,42);

        enc.encrypt(&mut cipher,&input);
        dec.decrypt(&mut output,&cipher);

        assert_eq!(output, input);
    }
}