OnchainTempo

Tempo blockchain primitives for Elixir — 0x76 transaction handling, TIP-20 token encoding, RPC broadcasting, and TransferWithMemo event parsing.

Built on onchain.

Installation

def deps do
  [
    {:onchain_tempo, "~> 0.13"}
  ]
end

Documentation: hexdocs.pm/onchain_tempo.

Modules

Quick Start

Deserialize a Tempo transaction

{:ok, tx} = Onchain.Tempo.Transaction.deserialize("0x76...")
tx.chain_id  #=> 42431
tx.calls     #=> [%{to: <<...>>, value: 0, input: <<...>>}]

Version 0.13 removes tx.fields. Read and update named struct fields, then call Transaction.serialize/1. raw retains the original broadcast hex; serialize/1 returns hex for the current fields. signing_hash/1, hash/1, and sender/1 return {:ok, binary}. Decode, serialization, hashing, fee-payer cosigning and recovery support Secp256k1, P-256, WebAuthn, and keychain V1/V2. Our builders sign with Secp256k1 keys. Keychain recovery verifies the inner signature, but callers must separately check access-key authorization on-chain.

Signatures are {:secp256k1, %{r: integer, s: integer, y_parity: 0 | 1}}, {:p256, %{r: binary, s: binary, pub_key_x: binary, pub_key_y: binary, pre_hash: boolean}}, {:webauthn, %{r: binary, s: binary, pub_key_x: binary, pub_key_y: binary, webauthn_data: binary}}, or {:keychain, 1 | 2, user_address_binary, primitive_signature}. Key authorizations are typed maps with atom keys; see t:Onchain.Tempo.Transaction.key_authorization/0. Multicall builders accept %{to: address_binary, value: integer, input: binary} calls.

Migration from 0.11 and 0.12

0.12 changed fields from positional RLP to an internal serde map without documenting the break, and restricted signatures to Secp256k1. 0.13 replaces both representations with named fields and restores all supported signatures. The 0.12 keys below lived under fields["transaction"] unless stated otherwise. Addresses/data now use binaries, quantities use integers, and absent optionals use nil. A fee-payer placeholder is :placeholder.

Transaction.sender/1 normalizes high-s Secp256k1 signatures to low-s before recovery, so equivalent complement-s encodings recover the same sender. It preserves the original envelope; successful recovery does not imply broadcast acceptance.

Find a payment call

{:ok, match} = Onchain.Tempo.Transaction.find_payment_call(tx, token_address,
  amount: "1000000",
  recipient: "0x70997970..."
)
match.amount  #=> 1000000

Build and sign a transfer

{:ok, tx_hex} = Onchain.Tempo.Transaction.Builder.build_signed_transfer(
  private_key: "0xac09...",
  token: "0x20c0...",
  recipient: "0x7099...",
  amount: 1_000_000,
  chain_id: 42_431,
  rpc_url: "https://rpc.moderato.tempo.xyz"
)

Broadcast

# Async (returns tx hash immediately)
{:ok, tx_hash} = Onchain.Tempo.RPC.broadcast_async(tx_hex, rpc_url)

# Sync (waits for block inclusion, returns receipt)
{:ok, tx_hash, receipt} = Onchain.Tempo.RPC.broadcast_sync(tx_hex, rpc_url)

Fund a Moderato testnet wallet

For integration tests against Moderato (testnet 42_431), Onchain.Tempo.Faucet wraps the non-standard tempo_fundAddress JSON-RPC:

# Fund an existing address.
{:ok, [tx_hash | _]} = Onchain.Tempo.Faucet.fund_address("0xabc...")

# Generate + fund a fresh keypair (polls for confirmation before returning).
{:ok, %{private_key: priv, address_hex: hex, address_bin: bin}} =
  Onchain.Tempo.Faucet.fresh_funded_wallet()

Defaults to https://rpc.moderato.tempo.xyz; overridable via TEMPO_RPC_URL or by passing rpc_url: in the opts (e.g. fund_address("0xabc...", rpc_url: "https://my-mirror")). Mainnet does not support tempo_fundAddress.

Discovery

All modules use descripex:

OnchainTempo.describe()                          # Module overview
OnchainTempo.describe(:transaction)              # Function list
OnchainTempo.describe(:transaction, :deserialize) # Full details

Tempo Networks

Which endpoint serves what

This package is Tempo-specific by design — it is not portable to an arbitrary Ethereum provider, and that is the point rather than an oversight. Type-0x76 transactions, TIP-20 encoding, and the synchronous broadcast path are Tempo protocol features; a generic Ethereum endpoint has no notion of them. What you can swap is which Tempo-compatible endpoint you point at — your own node, or a provider serving the Tempo chain — not the chain itself.

Every RPC function takes an rpc_url so you can target either network per call. The faucet additionally reads a TEMPO_RPC_URL environment variable as its default, falling back to https://rpc.moderato.tempo.xyz — set it to point the faucet at a different Moderato endpoint without threading a URL through every call (Onchain.Tempo.Faucet.rpc_url/0 returns the resolved value).

0x76 verification

Signing and canonical encoding are checked against the provider-owned Tempo transaction spec and the current ox TypeScript SDK (TxEnvelopeTempo), plus live Moderato broadcast success and a relevant decode error. Evidence lives in priv/verification/0x76/ (ledger, ox vectors, live observation). Unit tests under test/onchain/tempo/verification/ rerun the properties, differential checks and mutation campaign; live checks are the :integration suite.

License

MIT