#![allow(dead_code)] // TODO: remove
use super::SymKey;
use crate::{
err::{Error, Res},
hpke::{Aead, Kdf},
};
use hkdf::Hkdf as HkdfImpl;
use log::trace;
use sha2::{Sha256, Sha384, Sha512};
#[derive(Clone, Copy)]
pub enum KeyMechanism {
Aead(Aead),
#[allow(dead_code)] // We don't use this one.
Hkdf,
}
impl KeyMechanism {
fn len(self) -> usize {
match self {
Self::Aead(a) => a.n_k(),
Self::Hkdf => 0, // Let the underlying module decide.
}
}
}
pub enum Hkdf {
Sha256,
Sha384,
Sha512,
}
impl Hkdf {
pub fn new(kdf: Kdf) -> Self {
match kdf {
Kdf::HkdfSha256 => Self::Sha256,
Kdf::HkdfSha384 => Self::Sha384,
Kdf::HkdfSha512 => Self::Sha512,
}
}
#[cfg(test)]
#[allow(clippy::unnecessary_wraps)]
pub fn import_ikm(ikm: &[u8]) -> Res<SymKey> {
Ok(SymKey::from(ikm))
}
#[allow(clippy::unnecessary_wraps)]
pub fn extract(&self, salt: &[u8], ikm: &SymKey) -> Res<SymKey> {
let prk = match self {
Self::Sha256 => {
SymKey::from(HkdfImpl::<Sha256>::extract(Some(salt), &ikm.0).0.as_slice())
}
Self::Sha384 => {
SymKey::from(HkdfImpl::<Sha384>::extract(Some(salt), &ikm.0).0.as_slice())
}
Self::Sha512 => {
SymKey::from(HkdfImpl::<Sha512>::extract(Some(salt), &ikm.0).0.as_slice())
}
};
trace!(
"HKDF extract: salt={} ikm={:?} prk={:?}",
hex::encode(salt),
ikm,
prk
);
Ok(prk)
}
pub fn expand_key(&self, prk: &SymKey, info: &[u8], key_mech: KeyMechanism) -> Res<SymKey> {
let okm = SymKey::from(self.expand_data(prk, info, key_mech.len())?);
trace!(
"HKDF expand_key: prk={:?} info={} okm={:?}",
prk,
hex::encode(info),
okm,
);
Ok(okm)
}
pub fn expand_data(&self, prk: &SymKey, info: &[u8], len: usize) -> Res<Vec<u8>> {
let mut okm = vec![0; len];
match self {
Self::Sha256 => {
let h = HkdfImpl::<Sha256>::from_prk(&prk.0).map_err(|_| Error::Internal)?;
h.expand(info, &mut okm).map_err(|_| Error::Internal)?;
}
Self::Sha384 => {
let h = HkdfImpl::<Sha384>::from_prk(&prk.0).map_err(|_| Error::Internal)?;
h.expand(info, &mut okm).map_err(|_| Error::Internal)?;
}
Self::Sha512 => {
let h = HkdfImpl::<Sha512>::from_prk(&prk.0).map_err(|_| Error::Internal)?;
h.expand(info, &mut okm).map_err(|_| Error::Internal)?;
}
}
trace!(
"HKDF expand_data: prk={:?} info={} len={} okm={:?}",
prk,
hex::encode(info),
len,
hex::encode(&okm),
);
Ok(okm)
}
}
#[cfg(test)]
mod test {
use super::{super::super::hpke::Kdf, Hkdf};
use crate::init;
fn sha256_example(
ikm: &[u8],
salt: &[u8],
info: &[u8],
l: usize,
expected_prk: &[u8],
expected_okm: &[u8],
) {
init();
let hkdf = Hkdf::new(Kdf::HkdfSha256);
let k_ikm = Hkdf::import_ikm(ikm).unwrap();
let prk = hkdf.extract(salt, &k_ikm).unwrap();
let prk_data = prk.key_data().unwrap();
assert_eq!(prk_data, expected_prk);
let out = hkdf.expand_data(&prk, info, l).unwrap();
assert_eq!(&out[..], expected_okm);
}
/// Example 1 from <
https://tools.ietf.org/html/rfc5869#appendix-A.1>
#[test]
fn example1() {
const IKM: &[u8] = &[
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
];
const SALT: &[u8] = &[
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c,
];
const INFO: &[u8] = &[0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9];
const L: usize = 42;
const PRK: &[u8] = &[
0x07, 0x77, 0x09, 0x36, 0x2c, 0x2e, 0x32, 0xdf, 0x0d, 0xdc, 0x3f, 0x0d, 0xc4, 0x7b,
0xba, 0x63, 0x90, 0xb6, 0xc7, 0x3b, 0xb5, 0x0f, 0x9c, 0x31, 0x22, 0xec, 0x84, 0x4a,
0xd7, 0xc2, 0xb3, 0xe5,
];
const OKM: &[u8] = &[
0x3c, 0xb2, 0x5f, 0x25, 0xfa, 0xac, 0xd5, 0x7a, 0x90, 0x43, 0x4f, 0x64, 0xd0, 0x36,
0x2f, 0x2a, 0x2d, 0x2d, 0x0a, 0x90, 0xcf, 0x1a, 0x5a, 0x4c, 0x5d, 0xb0, 0x2d, 0x56,
0xec, 0xc4, 0xc5, 0xbf, 0x34, 0x00, 0x72, 0x08, 0xd5, 0xb8, 0x87, 0x18, 0x58, 0x65,
];
sha256_example(IKM, SALT, INFO, L, PRK, OKM);
}
/// Example 2 from <
https://tools.ietf.org/html/rfc5869#appendix-A.2>
#[test]
fn example2() {
const IKM: &[u8] = &[
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29,
0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
];
const SALT: &[u8] = &[
0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d,
0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b,
0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5,
0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
];
const INFO: &[u8] = &[
0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd,
0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb,
0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9,
0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5,
0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
];
const L: usize = 82;
const PRK: &[u8] = &[
0x06, 0xa6, 0xb8, 0x8c, 0x58, 0x53, 0x36, 0x1a, 0x06, 0x10, 0x4c, 0x9c, 0xeb, 0x35,
0xb4, 0x5c, 0xef, 0x76, 0x00, 0x14, 0x90, 0x46, 0x71, 0x01, 0x4a, 0x19, 0x3f, 0x40,
0xc1, 0x5f, 0xc2, 0x44,
];
const OKM: &[u8] = &[
0xb1, 0x1e, 0x39, 0x8d, 0xc8, 0x03, 0x27, 0xa1, 0xc8, 0xe7, 0xf7, 0x8c, 0x59, 0x6a,
0x49, 0x34, 0x4f, 0x01, 0x2e, 0xda, 0x2d, 0x4e, 0xfa, 0xd8, 0xa0, 0x50, 0xcc, 0x4c,
0x19, 0xaf, 0xa9, 0x7c, 0x59, 0x04, 0x5a, 0x99, 0xca, 0xc7, 0x82, 0x72, 0x71, 0xcb,
0x41, 0xc6, 0x5e, 0x59, 0x0e, 0x09, 0xda, 0x32, 0x75, 0x60, 0x0c, 0x2f, 0x09, 0xb8,
0x36, 0x77, 0x93, 0xa9, 0xac, 0xa3, 0xdb, 0x71, 0xcc, 0x30, 0xc5, 0x81, 0x79, 0xec,
0x3e, 0x87, 0xc1, 0x4c, 0x01, 0xd5, 0xc1, 0xf3, 0x43, 0x4f, 0x1d, 0x87,
];
sha256_example(IKM, SALT, INFO, L, PRK, OKM);
}
/// Example 3 from <
https://tools.ietf.org/html/rfc5869#appendix-A.3>
#[test]
fn example3() {
const IKM: &[u8] = &[
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
];
const SALT: &[u8] = &[];
const INFO: &[u8] = &[];
const L: usize = 42;
const PRK: &[u8] = &[
0x19, 0xef, 0x24, 0xa3, 0x2c, 0x71, 0x7b, 0x16, 0x7f, 0x33, 0xa9, 0x1d, 0x6f, 0x64,
0x8b, 0xdf, 0x96, 0x59, 0x67, 0x76, 0xaf, 0xdb, 0x63, 0x77, 0xac, 0x43, 0x4c, 0x1c,
0x29, 0x3c, 0xcb, 0x04,
];
const OKM: &[u8] = &[
0x8d, 0xa4, 0xe7, 0x75, 0xa5, 0x63, 0xc1, 0x8f, 0x71, 0x5f, 0x80, 0x2a, 0x06, 0x3c,
0x5a, 0x31, 0xb8, 0xa1, 0x1f, 0x5c, 0x5e, 0xe1, 0x87, 0x9e, 0xc3, 0x45, 0x4e, 0x5f,
0x3c, 0x73, 0x8d, 0x2d, 0x9d, 0x20, 0x13, 0x95, 0xfa, 0xa4, 0xb6, 0x1a, 0x96, 0xc8,
];
sha256_example(IKM, SALT, INFO, L, PRK, OKM);
}
}
