hmac/
simple_reset.rs

1use crate::utils::{IPAD, OPAD, get_der_key};
2use core::fmt;
3use digest::{
4    Digest, FixedOutput, KeyInit, MacMarker, Output, OutputSizeUser, Update,
5    common::{Block, BlockSizeUser, InvalidLength, Key, KeySizeUser},
6};
7use digest::{FixedOutputReset, Reset};
8
9/// Simplified HMAC instance with reset support able to operate
10/// over hash functions which do not expose block-level API and
11/// hash functions which process blocks lazily (e.g. BLAKE2).
12#[derive(Clone)]
13pub struct SimpleHmacReset<D: Digest + BlockSizeUser> {
14    digest: D,
15    opad_key: Block<D>,
16    ipad_key: Block<D>,
17}
18
19impl<D: Digest + BlockSizeUser> KeySizeUser for SimpleHmacReset<D> {
20    type KeySize = D::BlockSize;
21}
22
23impl<D: Digest + BlockSizeUser> MacMarker for SimpleHmacReset<D> {}
24
25impl<D: Digest + BlockSizeUser> KeyInit for SimpleHmacReset<D> {
26    fn new(key: &Key<Self>) -> Self {
27        Self::new_from_slice(key.as_slice()).unwrap()
28    }
29
30    #[inline]
31    fn new_from_slice(key: &[u8]) -> Result<Self, InvalidLength> {
32        let der_key = get_der_key::<D>(key);
33
34        let mut ipad_key = der_key.clone();
35        ipad_key.iter_mut().for_each(|b: &mut u8| *b ^= IPAD);
36
37        let mut digest = D::new();
38        digest.update(&ipad_key);
39
40        let mut opad_key = der_key;
41        opad_key.iter_mut().for_each(|b: &mut u8| *b ^= OPAD);
42
43        Ok(Self {
44            digest,
45            opad_key,
46            ipad_key,
47        })
48    }
49}
50
51impl<D: Digest + BlockSizeUser> Update for SimpleHmacReset<D> {
52    #[inline(always)]
53    fn update(&mut self, data: &[u8]) {
54        self.digest.update(data);
55    }
56}
57
58impl<D: Digest + BlockSizeUser> OutputSizeUser for SimpleHmacReset<D> {
59    type OutputSize = D::OutputSize;
60}
61
62impl<D: Digest + BlockSizeUser> FixedOutput for SimpleHmacReset<D> {
63    fn finalize_into(self, out: &mut Output<Self>) {
64        let mut h = D::new();
65        h.update(&self.opad_key);
66        h.update(self.digest.finalize());
67        h.finalize_into(out);
68    }
69}
70
71impl<D: Digest + BlockSizeUser + fmt::Debug> fmt::Debug for SimpleHmacReset<D> {
72    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
73        f.write_str("SimpleResetHmac")
74    }
75}
76
77impl<D: Digest + BlockSizeUser + Reset> Reset for SimpleHmacReset<D> {
78    fn reset(&mut self) {
79        Reset::reset(&mut self.digest);
80        self.digest.update(&self.ipad_key);
81    }
82}
83
84impl<D: Digest + BlockSizeUser + FixedOutputReset> FixedOutputReset for SimpleHmacReset<D> {
85    fn finalize_into_reset(&mut self, out: &mut Output<Self>) {
86        let mut h = D::new();
87        Update::update(&mut h, &self.opad_key);
88        Update::update(&mut h, &self.digest.finalize_reset());
89        Update::update(&mut self.digest, &self.ipad_key);
90        Digest::finalize_into(h, out);
91    }
92}
hmac/simple_reset.rs

hmac/
simple_reset.rs
