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fix(bc/pointer): cancel upper two bytes of payload bc they're node-specific

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Alain Zscheile 2022-09-27 17:17:27 +02:00
parent 911d662634
commit 7580ba28bb
1 changed files with 14 additions and 2 deletions
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16
crates/fogtix-bytecode/src/pointer.rs
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@ -77,10 +77,12 @@ impl Pointer {
fn calculate_hmac(payload: u64, key: &Atom) -> u64 {
use core::hash::Hasher;
let mut h = key.build_hasher();
h.write_u64(payload);
h.write_u64(payload & ((1 << 48) - 1));
h.finish()
}
/// SECURITY NOTE: the upper two bytes of `payload` (`origin`) aren't taken
/// into account when calculating the HMAC because they're node-specific
pub fn new_with_key(payload: u64, key: &Atom) -> Pointer {
let hmac = Self::calculate_hmac(payload, key);
Atom::from((hmac, payload)).into()
@ -172,8 +174,18 @@ mod tests {
let k = Atom([0, 0, 0, 0, 0, 0, 0xde, 0xad, 0, 0, 0, 0, 0, 0, 0xbe, 0xef]);
let p = Pointer::new_with_key(0x0508deadbeeffefe, &k);
// verify that this is the same value on all systems
assert_eq!(p.0[0..8], [98, 122, 191, 167, 34, 251, 28, 171]);
assert_eq!(p.0[0..8], [191, 23, 107, 0, 61, 74, 249, 219]);
assert_eq!(p.verify(&k), Some(0x0508deadbeeffefe));
assert_eq!(p.origin(), 0x0508);
}
#[test]
fn pointer_usage3() {
let k = Atom([0, 0, 0, 0, 0, 0, 0xde, 0xad, 0, 0, 0, 0, 0, 0, 0xbe, 0xef]);
let p = Pointer::new_with_key(0xf7d8deadbeeffefe, &k);
// verify that this is the same value on all systems
assert_eq!(p.0[0..8], [191, 23, 107, 0, 61, 74, 249, 219]);
assert_eq!(p.verify(&k), Some(0xf7d8deadbeeffefe));
assert_eq!(p.origin(), 0xf7d8);
}
}