metamorphic_log

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Elixir client for the metamorphic-log transparency-log engine. It surfaces the engine's verification + monitor SDK and its deterministic ingestion primitives to Elixir/Phoenix, powered by precompiled Rust NIFs — no Rust toolchain, no C compiler, no system packages required.

Everything here computes byte-for-byte identically to the engine's native Rust core and its browser WebAssembly SDK, because all three are thin shells over the same audited metamorphic-crypto and metamorphic-log crates. A log built by browser clients can therefore be recomputed and verified, unchanged, on the server.

What it does

  • Inclusion & consistency proofs — RFC 6962 / 9162 Merkle proof verification (MetamorphicLog.Proof).
  • Checkpoints & signed notes — C2SP signed-note and tlog-checkpoint parsing/verification with both classical Ed25519 and an additive hybrid post-quantum (ML-DSA + Ed25519) signature type (MetamorphicLog.Checkpoint, MetamorphicLog.Note).
  • CONIKS key transparency — privacy-preserving lookup/absence proof verification over an ECVRF-blinded directory, with SHA3-512 commitments (MetamorphicLog.Coniks, MetamorphicLog.Commitment).
  • Namespace policy — signed, in-log posture (suite/level/commitment/VRF mode) verification and declared == observed enforcement (MetamorphicLog.Policy).
  • Canonical leaves — the mosslet/key-history/v1 canonical encoding and hashes (MetamorphicLog.Leaf).
  • Ingestion primitives — content dedup keys, tile flush geometry, and Merkle recomputation for an Elixir operator pipeline (MetamorphicLog.Ingest).

Installation

def deps do
  [
    {:metamorphic_log, "~> 0.1"}
  ]
end

A precompiled NIF is downloaded for your platform on first build. To build the NIF from source instead (requires a Rust toolchain), set METAMORPHIC_LOG_BUILD=true.

Quick start

# Verify a checkpoint (signed tree head) against trusted verifier keys
{:ok, checkpoint} = MetamorphicLog.Checkpoint.verify(note_text, [vkey])

# Then verify that a leaf is included under that verified checkpoint
:ok =
  MetamorphicLog.Checkpoint.verify_inclusion(
    note_text, [vkey], leaf_index, leaf_hash, proof
  )

# Verify a namespace policy and enforce declared == observed posture
{:ok, %MetamorphicLog.Policy{commitment_hash: :sha3_256}} =
  MetamorphicLog.Policy.verify(signed_policy)

:ok = MetamorphicLog.Policy.enforce_vrf_suite_id(signed_policy, 0x03)

Wire format

Binary values (hashes, roots, proof nodes, keys, openings) cross the API as base64-encoded strings (standard padded alphabet); checkpoint/note bodies and verifier keys are UTF-8 text. This matches the browser WASM SDK and is what makes cross-target digests identical. Use Base.encode64/1 / Base.decode64/1 at your application boundary.

See the verification guide for the end-to-end monitor workflow.

Performance & the BEAM

CPU-bound work — proof verification, CONIKS VRF verification, signature verification (Ed25519 + ML-DSA), and Merkle recomputation — runs on Erlang dirty CPU schedulers, so bursts of verification never block the normal schedulers. Genuine micro-operations (canonical framing, single-hash leaf and dedup digests, parsing, flush geometry) run inline.

License

Licensed under either of MIT or Apache-2.0 at your option.