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HMAC: only 32 byte keys (#424)

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* only support HMAC with 32 byte keys

* includes HMAC in the trait to be generic

* re-added HAMC test
This commit is contained in:
kaczmarczyck
2022-01-18 13:14:11 +01:00
committed by GitHub
parent ce08f82d68
commit 98c9191679
5 changed files with 165 additions and 299 deletions
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146
libraries/crypto/src/hkdf.rs
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@@ -38,117 +38,12 @@ where
hmac_256::<H>(&prk, t.as_slice())
}
/// Computes the HKDF.
///
/// # Arguments
///
/// * `salt` - Optional salt value (a non-secret random value)
/// * `ikm` - Input keying material
/// * `l` - Length of output keying material in octets
/// * `info` - Optional context and application specific information
///
/// Defined in RFC: https://tools.ietf.org/html/rfc5869
///
/// `salt` and `info` can be be empty. `salt` then defaults to one block of
/// zeros of size `HASH_SIZE`. Argument order is taken from:
/// https://fidoalliance.org/specs/fido-v2.1-rd-20201208/fido-client-to-authenticator-protocol-v2.1-rd-20201208.html#pinProto2
#[cfg(test)]
pub fn hkdf<H>(salt: &[u8], ikm: &[u8], l: u8, info: &[u8]) -> Vec<u8>
where
H: Hash256,
{
let prk = if salt.is_empty() {
hmac_256::<H>(&[0; HASH_SIZE], ikm)
} else {
hmac_256::<H>(salt, ikm)
};
let mut t = vec![];
let mut okm = vec![];
for i in 0..(l as usize + HASH_SIZE - 1) / HASH_SIZE {
t.extend_from_slice(info);
t.push((i + 1) as u8);
t = hmac_256::<H>(&prk, t.as_slice()).to_vec();
okm.extend_from_slice(t.as_slice());
}
okm.truncate(l as usize);
okm
}
#[cfg(test)]
mod test {
use super::super::sha256::Sha256;
use super::*;
use arrayref::array_ref;
#[test]
fn test_hkdf_sha256_vectors() {
// Test vectors taken from https://tools.ietf.org/html/rfc5869.
let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
let salt = hex::decode("000102030405060708090a0b0c").unwrap();
let info = hex::decode("f0f1f2f3f4f5f6f7f8f9").unwrap();
let l = 42;
let okm = hex::decode(
"3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865",
)
.unwrap();
assert_eq!(
hkdf::<Sha256>(salt.as_slice(), ikm.as_slice(), l, info.as_slice()),
okm
);
let ikm = hex::decode(
"000102030405060708090a0b0c0d0e0f\
101112131415161718191a1b1c1d1e1f\
202122232425262728292a2b2c2d2e2f\
303132333435363738393a3b3c3d3e3f\
404142434445464748494a4b4c4d4e4f",
)
.unwrap();
let salt = hex::decode(
"606162636465666768696a6b6c6d6e6f\
707172737475767778797a7b7c7d7e7f\
808182838485868788898a8b8c8d8e8f\
909192939495969798999a9b9c9d9e9f\
a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
)
.unwrap();
let info = hex::decode(
"b0b1b2b3b4b5b6b7b8b9babbbcbdbebf\
c0c1c2c3c4c5c6c7c8c9cacbcccdcecf\
d0d1d2d3d4d5d6d7d8d9dadbdcdddedf\
e0e1e2e3e4e5e6e7e8e9eaebecedeeef\
f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
)
.unwrap();
let l = 82;
let okm = hex::decode(
"b11e398dc80327a1c8e7f78c596a4934\
4f012eda2d4efad8a050cc4c19afa97c\
59045a99cac7827271cb41c65e590e09\
da3275600c2f09b8367793a9aca3db71\
cc30c58179ec3e87c14c01d5c1f3434f\
1d87",
)
.unwrap();
assert_eq!(
hkdf::<Sha256>(salt.as_slice(), ikm.as_slice(), l, info.as_slice()),
okm
);
let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
let salt = hex::decode("").unwrap();
let info = hex::decode("").unwrap();
let l = 42;
let okm = hex::decode(
"8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395faa4b61a96c8",
)
.unwrap();
assert_eq!(
hkdf::<Sha256>(salt.as_slice(), ikm.as_slice(), l, info.as_slice()),
okm
);
}
#[test]
fn test_hkdf_empty_salt_256_sha256_vectors() {
// Test vectors generated by pycryptodome using:
@@ -182,45 +77,4 @@ mod test {
);
}
}
#[test]
fn test_hkdf_length() {
let salt = [];
let mut input = Vec::new();
for l in 0..128 {
assert_eq!(
hkdf::<Sha256>(&salt, input.as_slice(), l, input.as_slice()).len(),
l as usize
);
input.push(b'A');
}
}
#[test]
fn test_hkdf_empty_salt() {
let salt = [];
let mut input = Vec::new();
for l in 0..128 {
assert_eq!(
hkdf::<Sha256>(&salt, input.as_slice(), l, input.as_slice()),
hkdf::<Sha256>(&[0; 32], input.as_slice(), l, input.as_slice())
);
input.push(b'A');
}
}
#[test]
fn test_hkdf_compare_implementations() {
let salt = [];
let l = 32;
let mut input = Vec::new();
for _ in 0..128 {
assert_eq!(
hkdf::<Sha256>(&salt, input.as_slice(), l, input.as_slice()),
hkdf_empty_salt_256::<Sha256>(input.as_slice(), input.as_slice())
);
input.push(b'A');
}
}
}