core_crypto_keystore/
hash.rs

1use std::fmt;
2
3use sha2::{Digest, Sha256};
4
5use crate::{CryptoKeystoreResult, traits::KeyType};
6
7/// Used to calculate ID hashes for some MlsEntities' SQLite tables (not used on wasm).
8/// We only use sha256 on platforms where we use SQLite.
9/// On wasm, we use IndexedDB, a key-value store, via the idb crate.
10#[cfg(not(target_family = "wasm"))]
11pub(crate) fn sha256(data: &[u8]) -> String {
12    Sha256Hash::hash_from(data).to_string()
13}
14
15/// A Sha256 hash.
16///
17/// Certain entities use this kind of hash as a key. It's a small value which lives on the stack,
18/// as opposed to the longer, heap-allocated values which it replaces.
19///
20/// This type enables this use case with the new entity traits.
21#[derive(
22    Debug,
23    Default,
24    Clone,
25    Copy,
26    PartialEq,
27    Eq,
28    PartialOrd,
29    Ord,
30    Hash,
31    derive_more::Deref,
32    derive_more::AsRef,
33    derive_more::From,
34    derive_more::Into,
35)]
36#[as_ref(forward)]
37pub struct Sha256Hash([u8; 32]);
38
39impl Sha256Hash {
40    /// Create an instance by hashing a single input value.
41    pub fn hash_from(input: impl AsRef<[u8]>) -> Self {
42        let mut hasher = Sha256::new();
43        hasher.update(input);
44        Self(hasher.finalize().into())
45    }
46
47    /// Convert an existing hash into an instance of this type.
48    ///
49    /// Only basic length checking is performed!
50    pub fn from_existing_hash(hash: impl AsRef<[u8]>) -> CryptoKeystoreResult<Self> {
51        let array = hash.as_ref().try_into()?;
52        Ok(Self(array))
53    }
54}
55
56impl fmt::Display for Sha256Hash {
57    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
58        let mut hex_bytes = [0; 64];
59        hex::encode_to_slice(self.0, hex_bytes.as_mut_slice())
60            .expect("infallible given inputs and outputs of fixed correct length");
61        let hex_str = str::from_utf8(&hex_bytes).expect("hex crate always produces valid utf8 data");
62        write!(f, "{hex_str}")
63    }
64}
65
66impl KeyType for Sha256Hash {
67    fn bytes(&self) -> std::borrow::Cow<'_, [u8]> {
68        (&self.0).into()
69    }
70}
71
72#[cfg(not(target_family = "wasm"))]
73impl rusqlite::ToSql for Sha256Hash {
74    fn to_sql(&self) -> rusqlite::Result<rusqlite::types::ToSqlOutput<'_>> {
75        self.as_ref().to_sql()
76    }
77}
core_crypto_keystore/hash.rs

core_crypto_keystore/
hash.rs
