Brings Amethyst's Marmot code into wire-level interoperability with the
reference MDK (Rust) implementation by resolving four spec violations and
tightening the epoch lookback window:
- MIP-01 (NostrGroupData extension): switch to QUIC-style VarInt length
prefixes (RFC 9000 §16) instead of fixed uint16. MIP-01 mandates this
encoding (the one produced by the Rust `tls_codec` crate v0.4+), so
Amethyst's previous uint16 framing could not round-trip with any MDK
peer. admin_pubkeys, relays (outer + each inner), name, description,
image_*, and disappearing_message_secs now all use VarInt prefixes.
- MIP-01: enforce "admin_pubkeys MUST NOT contain duplicates" in the
MarmotGroupData constructor.
- MIP-05 (Push Notifications): token plaintext padded size was 220 (→ 280
encrypted); spec MUSTs are exactly 1024 bytes plaintext (1084 encrypted).
A server expecting MIP-05 tokens would reject Amethyst's frames outright.
- MIP-05: HKDF IKM was sha256(shared_point); spec requires the raw 32-byte
ECDH x-coordinate. The extra sha256 produced a different PRK, so token
ciphertext authenticated only within Amethyst. Removed the hash; ECDH
already returns the x-only compact form via pubKeyTweakMulCompact.
- MIP-03: bump EPOCH_RETENTION_WINDOW from 2 to 5 to match MDK's
DEFAULT_EPOCH_LOOKBACK, so late-arriving GroupEvents whose ChaCha20
outer key was derived from a prior epoch's exporter secret can still
be decrypted after a Commit advances the group.
Hand-crafted MarmotGroupData test blobs were updated to emit VarInt
length prefixes.
Claude
1569b45671