belt-dwp 0.1.0

Pure Rust implementation of the Belt-DWP authenticated encryption algorithm (STB 34.101.31-2020)
Documentation 
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use aead::array::Array;
use aead::consts::{U1, U16};
use aead::{KeyInit, KeySizeUser};
use belt_block::cipher::{BlockSizeUser, ParBlocksSizeUser};
use universal_hash::{Reset, UhfBackend, UhfClosure, UniversalHash};

use crate::gf::gf128_soft64::Element;

/// GHASH keys (16-bytes)
pub type Key = Array<u8, U16>;

/// GHASH blocks (16-bytes)
pub type Block = Array<u8, U16>;

/// GHASH tags (16-bytes)
pub type Tag = Array<u8, U16>;

#[derive(Clone)]
pub struct GHash {
    s: Element,
    h: Element,
}

impl KeySizeUser for GHash {
    type KeySize = U16;
}

impl BlockSizeUser for GHash {
    type BlockSize = U16;
}

impl KeyInit for GHash {
    fn new(h: &Key) -> Self {
        Self::new_with_init_block(h, 0)
    }
}

impl GHash {
    pub(crate) fn new_with_init_block(h: &Key, s: u128) -> Self {
        Self {
            s: Element::from(s),
            h: Element::from(h),
        }
    }
}

impl ParBlocksSizeUser for GHash {
    type ParBlocksSize = U1;
}

impl UhfBackend for GHash {
    fn proc_block(&mut self, x: &Block) {
        self.s = (self.s + Element::from(x)) * self.h;
    }
}

impl UniversalHash for GHash {
    fn update_with_backend(&mut self, f: impl UhfClosure<BlockSize = Self::BlockSize>) {
        f.call(self);
    }

    /// Get GHASH output
    #[inline]
    fn finalize(self) -> Tag {
        self.s.into()
    }
}

impl Reset for GHash {
    fn reset(&mut self) {
        self.s = Element::default();
    }
}