nettle 3.0.0

Rust bindings for the Nettle cryptographic library
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use nettle_sys::{
    aes128_ctx,
    nettle_aes128_invert_key,
    nettle_aes128_set_encrypt_key,
    nettle_aes128_set_decrypt_key,
    nettle_aes128_encrypt,
    nettle_aes128_decrypt,
};
use std::mem::zeroed;
use std::os::raw::c_void;
use std::cmp::min;
use Cipher;
use Error;
use Result;
use cipher::RawCipherFunctionPointer;

/// 128 bit variant of the Advanced Encryption Standard (AES, formerly RIJNDAEL) defined in FIPS 197.
pub struct Aes128 {
    context: aes128_ctx,
}

impl Aes128 {
    /// Creates a new `Aes128` instance for decryption that uses the same key as `encrypt`. The
    /// `encrypt` instance must be configured for encryption. This is faster than calling
    /// `with_decrypt_key`.
    pub fn with_inverted_key(encrypt: &Self) -> Self {
        let mut ctx = unsafe { zeroed() };
        unsafe {
            nettle_aes128_invert_key(
                &mut ctx as *mut _,
                &encrypt.context as *const _);
        }

        Aes128{ context: ctx }
    }
}

impl Cipher for Aes128 {
    const BLOCK_SIZE: usize = ::nettle_sys::AES_BLOCK_SIZE as usize;
    const KEY_SIZE: usize = ::nettle_sys::AES128_KEY_SIZE as usize;

    fn with_encrypt_key(key: &[u8]) -> Result<Aes128> {
        if key.len() != Aes128::KEY_SIZE {
            return Err(Error::InvalidArgument{ argument_name: "key" }.into());
        }
        let mut ctx = unsafe { zeroed() };
        unsafe { nettle_aes128_set_encrypt_key(&mut ctx as *mut _, key.as_ptr()); }

        Ok(Aes128{ context: ctx })
    }

    fn with_decrypt_key(key: &[u8]) -> Result<Aes128> {
        if key.len() != Aes128::KEY_SIZE {
            return Err(Error::InvalidArgument{ argument_name: "key" }.into());
        }
        let mut ctx = unsafe { zeroed() };
        unsafe { nettle_aes128_set_decrypt_key(&mut ctx as *mut _, key.as_ptr()); }

        Ok(Aes128{ context: ctx })
    }

    fn encrypt(&mut self, dst: &mut [u8], src: &[u8]) {
        unsafe {
            nettle_aes128_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_aes128_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 aes128_ctx) as *mut c_void
    }

    fn raw_encrypt_function() -> RawCipherFunctionPointer {
        RawCipherFunctionPointer::new(nettle_aes128_encrypt)
    }

    fn raw_decrypt_function() -> RawCipherFunctionPointer {
        RawCipherFunctionPointer::new(nettle_aes128_decrypt)
    }
}

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

    #[test]
    fn set_key() {
        let key = &(b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16"[..]);
        let _ = Aes128::with_encrypt_key(key).unwrap();
        let _ = Aes128::with_decrypt_key(key).unwrap();
    }

    #[test]
    fn round_trip() {
        let key = vec![0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x10,0x11,0x12,0x13,0x14,0x15,0x16,];
        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 = Aes128::with_encrypt_key(&key).unwrap();
        let mut dec = Aes128::with_decrypt_key(&key).unwrap();

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

        assert_eq!(output, input);
    }

    #[test]
    fn round_trip_invert() {
        let key = vec![0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x10,0x11,0x12,0x13,0x14,0x15,0x16,];
        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 = Aes128::with_encrypt_key(&key).unwrap();
        let mut dec = Aes128::with_inverted_key(&enc);

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

        assert_eq!(output, input);
    }
}