bc_components/encrypted_key/
hkdf_params.rs

1use anyhow::Result;
2use bc_crypto::{hash::hkdf_hmac_sha512, hkdf_hmac_sha256};
3use dcbor::prelude::*;
4
5use super::{HashType, KeyDerivation, SALT_LEN};
6use crate::{EncryptedMessage, KeyDerivationMethod, Nonce, Salt, SymmetricKey};
7
8/// Struct representing HKDF parameters.
9///
10/// CDDL:
11/// ```cddl
12/// HKDFParams = [0, Salt, HashType]
13/// ```
14#[derive(Debug, Clone, PartialEq, Eq)]
15pub struct HKDFParams {
16    salt: Salt,
17    hash_type: HashType,
18}
19
20impl HKDFParams {
21    pub fn new() -> Self {
22        Self::new_opt(Salt::new_with_len(SALT_LEN).unwrap(), HashType::SHA256)
23    }
24
25    pub fn new_opt(salt: Salt, hash_type: HashType) -> Self {
26        Self { salt, hash_type }
27    }
28
29    pub fn salt(&self) -> &Salt { &self.salt }
30
31    pub fn hash_type(&self) -> HashType { self.hash_type }
32}
33
34impl KeyDerivation for HKDFParams {
35    const INDEX: usize = KeyDerivationMethod::HKDF as usize;
36
37    fn lock(
38        &mut self,
39        content_key: &SymmetricKey,
40        secret: impl AsRef<[u8]>,
41    ) -> Result<EncryptedMessage> {
42        let derived_key: SymmetricKey = (match self.hash_type {
43            HashType::SHA256 => hkdf_hmac_sha256(secret, &self.salt, 32),
44            HashType::SHA512 => hkdf_hmac_sha512(secret, &self.salt, 32),
45        })
46        .try_into()
47        .unwrap();
48        let encoded_method: Vec<u8> = self.to_cbor_data();
49        Ok(derived_key.encrypt(
50            content_key,
51            Some(encoded_method),
52            Option::<Nonce>::None,
53        ))
54    }
55
56    fn unlock(
57        &self,
58        encrypted_message: &EncryptedMessage,
59        secret: impl AsRef<[u8]>,
60    ) -> Result<SymmetricKey> {
61        let derived_key: SymmetricKey = (match self.hash_type {
62            HashType::SHA256 => hkdf_hmac_sha256(secret, &self.salt, 32),
63            HashType::SHA512 => hkdf_hmac_sha512(secret, &self.salt, 32),
64        })
65        .try_into()?;
66        let content_key = derived_key.decrypt(encrypted_message)?.try_into()?;
67        Ok(content_key)
68    }
69}
70
71impl std::fmt::Display for HKDFParams {
72    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
73        write!(f, "HKDF({})", self.hash_type)
74    }
75}
76
77impl Into<CBOR> for HKDFParams {
78    fn into(self) -> CBOR {
79        vec![
80            CBOR::from(Self::INDEX),
81            self.salt.into(),
82            self.hash_type.into(),
83        ]
84        .into()
85    }
86}
87
88impl TryFrom<CBOR> for HKDFParams {
89    type Error = dcbor::Error;
90
91    fn try_from(cbor: CBOR) -> dcbor::Result<Self> {
92        let a = cbor.try_into_array()?;
93        a.len()
94            .eq(&3)
95            .then_some(())
96            .ok_or_else(|| dcbor::Error::msg("Invalid HKDFParams"))?;
97        let mut iter = a.into_iter();
98        let _index: usize = iter
99            .next()
100            .ok_or_else(|| dcbor::Error::msg("Missing index"))?
101            .try_into()?;
102        let salt: Salt = iter
103            .next()
104            .ok_or_else(|| dcbor::Error::msg("Missing salt"))?
105            .try_into()?;
106        let hash_type: HashType = iter
107            .next()
108            .ok_or_else(|| dcbor::Error::msg("Missing hash type"))?
109            .try_into()?;
110        Ok(Self { salt, hash_type })
111    }
112}
bc_components/encrypted_key/hkdf_params.rs

bc_components/encrypted_key/
hkdf_params.rs
