mirror of https://github.com/ospab/ostp.git
ospab
f904695760
Every datagram from an unrecognized source ran the full key-trial loop:
for each registered access key, an HKDF (derive_all_secrets) plus two
HMACs (junk markers) plus a Noise read. A garbage flood from spoofed
sources could therefore force unbounded O(N_keys) crypto per packet — a
CPU-amplification DoS with no throttle (the existing token bucket only
guarded the roaming path, not this one).
Two mitigations:
- Memoize the per-key derived secrets (pure function of key+version) and
the per-window junk markers, so the trial loop is now cheap comparisons
plus one Noise read per key instead of HKDF+2*HMAC per key per packet.
Also speeds up every legitimate new connection. Caches are pruned in
on_tick when keys are deleted.
- Gate the trial path behind a global token bucket (TRIAL_RATE=100/s,
same burst). The established-session fast path and roaming are not
gated, so live sessions are unaffected; only unknown-datagram trials
are bounded. Over-budget datagrams are dropped silently.
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| .. | ||
| aead.rs | ||
| mod.rs | ||
| noise.rs | ||
| obfuscation.rs | ||
| obfuscation_tests.rs | ||