lexe_sha256/
sha256.rs

1use std::io;
2
3use lexe_byte_array::ByteArray;
4use ref_cast::RefCast;
5
6pub const HASH_LEN: usize = 32;
7
8/// A SHA-256 Hash value.
9#[derive(Copy, Clone, Default, Eq, Hash, PartialEq, RefCast)]
10#[repr(transparent)]
11pub struct Hash([u8; 32]);
12
13/// A SHA-256 digest accumulator.
14#[derive(Clone)]
15pub struct Context(ring::digest::Context);
16
17/// SHA-256 digest a single input.
18pub fn digest(input: &[u8]) -> Hash {
19    digest_many(&[input])
20}
21
22/// SHA-256 digest several input slices concatenated together, without
23/// allocating.
24pub fn digest_many(inputs: &[&[u8]]) -> Hash {
25    let mut ctx = Context::new();
26    for input in inputs {
27        ctx.update(input);
28    }
29    ctx.finish()
30}
31
32// -- impl Hash -- //
33
34impl Hash {
35    pub const fn new(value: [u8; 32]) -> Self {
36        Self(value)
37    }
38
39    // Note: not pub, since `ring::digest::Digest` is not always SHA-256, but
40    // we can guarantee this invariant inside the module.
41    fn from_ring(output: ring::digest::Digest) -> Self {
42        Self::new(<[u8; 32]>::try_from(output.as_ref()).unwrap())
43    }
44}
45
46lexe_byte_array::impl_byte_array!(Hash, 32);
47lexe_byte_array::impl_fromstr_fromhex!(Hash, 32);
48lexe_byte_array::impl_debug_display_as_hex!(Hash);
49
50// -- impl Context -- //
51
52impl Context {
53    pub fn new() -> Self {
54        Self(ring::digest::Context::new(&ring::digest::SHA256))
55    }
56
57    pub fn update(&mut self, input: &[u8]) {
58        self.0.update(input);
59    }
60
61    pub fn finish(self) -> Hash {
62        Hash::from_ring(self.0.finish())
63    }
64}
65
66impl Default for Context {
67    fn default() -> Self {
68        Self::new()
69    }
70}
71
72impl io::Write for Context {
73    fn write(&mut self, input: &[u8]) -> io::Result<usize> {
74        self.update(input);
75        Ok(input.len())
76    }
77
78    fn flush(&mut self) -> io::Result<()> {
79        Ok(())
80    }
81}
82
83#[cfg(test)]
84mod test {
85    use lexe_hex::hex;
86
87    use crate::sha256;
88
89    // sanity check
90    #[test]
91    fn test_sha256() {
92        let actual = hex::encode(sha256::digest(b"").as_ref());
93        let expected =
94            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
95        assert_eq!(&actual, expected);
96    }
97}
lexe_sha256/sha256.rs

lexe_sha256/
sha256.rs
