1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155

//! This crate defines a set of simple traits used to define functionality of
//! [block ciphers][1].
//!
//! # About block ciphers
//!
//! Block ciphers are keyed, deterministic permutations of a fixed-sized input
//! "block" providing a reversible transformation to/from an encrypted output.
//! They are one of the fundamental structural components of [symmetric cryptography][2].
//!
//! [1]: https://en.wikipedia.org/wiki/Block_cipher
//! [2]: https://en.wikipedia.org/wiki/Symmetric-key_algorithm

#![no_std]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![doc(html_logo_url = "https://raw.githubusercontent.com/RustCrypto/meta/master/logo_small.png")]
#![forbid(unsafe_code)]
#![warn(missing_docs, rust_2018_idioms)]

#[cfg(feature = "std")]
extern crate std;

#[cfg(feature = "dev")]
#[cfg_attr(docsrs, doc(cfg(feature = "dev")))]
pub mod dev;

mod errors;

pub use crate::errors::InvalidKeyLength;
pub use generic_array::{self, typenum::consts};

use generic_array::typenum::Unsigned;
use generic_array::{ArrayLength, GenericArray};

/// Key for an algorithm that implements [`NewBlockCipher`].
pub type Key<B> = GenericArray<u8, <B as NewBlockCipher>::KeySize>;

/// Block on which a [`BlockCipher`] operates.
pub type Block<B> = GenericArray<u8, <B as BlockCipher>::BlockSize>;

/// Blocks being acted over in parallel.
pub type ParBlocks<B> = GenericArray<Block<B>, <B as BlockCipher>::ParBlocks>;

/// Instantiate a [`BlockCipher`] algorithm.
pub trait NewBlockCipher: Sized {
    /// Key size in bytes with which cipher guaranteed to be initialized.
    type KeySize: ArrayLength<u8>;

    /// Create new block cipher instance from key with fixed size.
    fn new(key: &Key<Self>) -> Self;

    /// Create new block cipher instance from key with variable size.
    ///
    /// Default implementation will accept only keys with length equal to
    /// `KeySize`, but some ciphers can accept range of key lengths.
    fn new_varkey(key: &[u8]) -> Result<Self, InvalidKeyLength> {
        if key.len() != Self::KeySize::to_usize() {
            Err(InvalidKeyLength)
        } else {
            Ok(Self::new(GenericArray::from_slice(key)))
        }
    }
}

/// The trait which defines in-place encryption and decryption
/// over single block or several blocks in parallel.
pub trait BlockCipher {
    /// Size of the block in bytes
    type BlockSize: ArrayLength<u8>;

    /// Number of blocks which can be processed in parallel by
    /// cipher implementation
    type ParBlocks: ArrayLength<Block<Self>>;

    /// Encrypt block in-place
    fn encrypt_block(&self, block: &mut Block<Self>);

    /// Decrypt block in-place
    fn decrypt_block(&self, block: &mut Block<Self>);

    /// Encrypt several blocks in parallel using instruction level parallelism
    /// if possible.
    ///
    /// If `ParBlocks` equals to 1 it's equivalent to `encrypt_block`.
    #[inline]
    fn encrypt_blocks(&self, blocks: &mut ParBlocks<Self>) {
        for block in blocks.iter_mut() {
            self.encrypt_block(block);
        }
    }

    /// Decrypt several blocks in parallel using instruction level parallelism
    /// if possible.
    ///
    /// If `ParBlocks` equals to 1 it's equivalent to `decrypt_block`.
    #[inline]
    fn decrypt_blocks(&self, blocks: &mut ParBlocks<Self>) {
        for block in blocks.iter_mut() {
            self.decrypt_block(block);
        }
    }
}

/// Stateful block cipher which permits `&mut self` access.
///
/// The main use case for this trait is hardware encryption engines which
/// require `&mut self` access to an underlying hardware peripheral.
pub trait BlockCipherMut {
    /// Size of the block in bytes
    type BlockSize: ArrayLength<u8>;

    /// Encrypt block in-place
    fn encrypt_block(&mut self, block: &mut GenericArray<u8, Self::BlockSize>);

    /// Decrypt block in-place
    fn decrypt_block(&mut self, block: &mut GenericArray<u8, Self::BlockSize>);
}

impl<Alg: BlockCipher> BlockCipherMut for Alg {
    type BlockSize = Alg::BlockSize;

    #[inline]
    fn encrypt_block(&mut self, block: &mut GenericArray<u8, Self::BlockSize>) {
        <Self as BlockCipher>::encrypt_block(self, block);
    }

    #[inline]
    fn decrypt_block(&mut self, block: &mut GenericArray<u8, Self::BlockSize>) {
        <Self as BlockCipher>::decrypt_block(self, block);
    }
}

impl<Alg: BlockCipher> BlockCipher for &Alg {
    type BlockSize = Alg::BlockSize;
    type ParBlocks = Alg::ParBlocks;

    #[inline]
    fn encrypt_block(&self, block: &mut Block<Self>) {
        Alg::encrypt_block(self, block);
    }

    #[inline]
    fn decrypt_block(&self, block: &mut Block<Self>) {
        Alg::decrypt_block(self, block);
    }

    #[inline]
    fn encrypt_blocks(&self, blocks: &mut ParBlocks<Self>) {
        Alg::encrypt_blocks(self, blocks);
    }

    #[inline]
    fn decrypt_blocks(&self, blocks: &mut ParBlocks<Self>) {
        Alg::decrypt_blocks(self, blocks);
    }
}