use alloc::vec::Vec;
use core::iter::repeat;
use crate::digest::Digest;
use crate::hmac::Hmac;
use crate::mac::Mac;
pub fn hkdf_extract<D: Digest>(mut digest: D, salt: &[u8], ikm: &[u8], prk: &mut [u8]) {
assert!(prk.len() == digest.output_bytes());
digest.reset();
let mut mac = Hmac::new(digest, salt);
mac.input(ikm);
mac.raw_result(prk);
mac.reset();
}
pub fn hkdf_expand<D: Digest>(mut digest: D, prk: &[u8], info: &[u8], okm: &mut [u8]) {
digest.reset();
let mut mac = Hmac::new(digest, prk);
let os = mac.output_bytes();
let mut t: Vec<u8> = repeat(0).take(os).collect();
let mut n: u8 = 0;
for chunk in okm.chunks_mut(os) {
n = n.checked_add(1).expect("HKDF size limit exceeded.");
if n != 1 {
mac.input(&t[..]);
}
let nbuf = [n];
mac.input(info);
mac.input(&nbuf);
mac.raw_result(&mut t);
mac.reset();
let chunk_len = chunk.len();
chunk[0..chunk_len].copy_from_slice(&t[..chunk_len]);
}
}
#[cfg(test)]
mod test {
use alloc::vec::Vec;
use core::iter::repeat;
use crate::digest::Digest;
use crate::hkdf::{hkdf_expand, hkdf_extract};
use crate::sha2::Sha256;
struct TestVector<D: Digest> {
digest: D,
ikm: Vec<u8>,
salt: Vec<u8>,
info: Vec<u8>,
l: usize,
prk: Vec<u8>,
okm: Vec<u8>,
}
#[test]
fn test_hkdf_rfc5869_sha256_vectors() {
let test_vectors = vec![
TestVector {
digest: Sha256::new(),
ikm: repeat(0x0b).take(22).collect(),
salt: (0x00..=0x0c).collect(),
info: (0xf0..=0xf9).collect(),
l: 42,
prk: vec![
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,
],
okm: vec![
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,
],
},
TestVector {
digest: Sha256::new(),
ikm: (0x00..=0x4f).collect(),
salt: (0x60..=0xaf).collect(),
info: (0xb0..=0xff).map(|x| x as u8).collect(),
l: 82,
prk: vec![
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,
],
okm: vec![
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,
],
},
TestVector {
digest: Sha256::new(),
ikm: repeat(0x0b).take(22).collect(),
salt: vec![],
info: vec![],
l: 42,
prk: vec![
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,
],
okm: vec![
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,
],
},
];
for t in test_vectors.iter() {
let mut prk: Vec<u8> = repeat(0).take(t.prk.len()).collect();
hkdf_extract(t.digest.clone(), &t.salt[..], &t.ikm[..], &mut prk);
assert!(prk == t.prk);
let mut okm: Vec<u8> = repeat(0).take(t.okm.len()).collect();
assert!(okm.len() == t.l);
hkdf_expand(t.digest.clone(), &prk[..], &t.info[..], &mut okm);
assert!(okm == t.okm);
}
}
}