Hedera (hedera_ex)

A native Elixir SDK for the Hedera network — keys, identifiers, protobuf encoding, and (incrementally) the Consensus Service. No NIFs for the core crypto; no Java/Python bridge.

Status: alpha — but it talks to the network. The crypto/encoding foundation is unit-tested offline, and building, signing and submitting a Consensus Service message has been validated against the live Hedera testnet (the node accepts the natively-signed transaction). APIs may still change; receipt queries and broader services are next.

It exists because the Elixir ecosystem has no maintained Hedera SDK — projects that need on-chain anchoring from the BEAM currently shell out to the Python/Java SDKs. This library brings the hard parts (Hedera's exact signing conventions and protobuf/gRPC wire format) into pure, tested Elixir.

What works today

Area	Module(s)	Notes
Keccak-256	`Hedera.Crypto.Keccak`	Pure Elixir; the Ethereum/Hedera padding (not SHA3). Matches known vectors.
Ed25519 keys	`Hedera.PrivateKey`, `Hedera.PublicKey`	Generate, sign, verify, hex round-trip.
ECDSA secp256k1 keys	same	Hedera convention: Keccak-256 prehash, canonical low-S 64-byte `r‖s`, 33-byte compressed public key.
Identifiers	`Hedera.AccountId`, `Hedera.TopicId`, `Hedera.Timestamp`, `Hedera.TransactionId`, `Hedera.Duration`	Parse / format / protobuf-encode.
Protobuf	`Hedera.Proto`	Minimal proto3 wire encoder + decoder.
Transactions	`Hedera.Transaction`	Encode + sign `TransactionBody` → `SignedTransaction` → `Transaction` for HCS create / submit.
gRPC	`Hedera.Grpc`, `Hedera.Client`, `Hedera.Network`	Unary calls over HTTP/2 (h2c) to consensus nodes; HCS submit verified live on testnet.
Receipts	`Hedera.Client.transaction_receipt/3`, `Hedera.Receipt`	Free gRPC `getTransactionReceipts` poll → status + topic sequence number + running hash. Verified live.
Mirror node	`Hedera.MirrorNode`	REST reads (topic messages, transactions).

alias Hedera.{AccountId, Client, PrivateKey, TopicId}

client =
  Client.testnet(
    AccountId.parse("0.0.8260469"),
    PrivateKey.from_string_ecdsa(System.fetch_env!("OPERATOR_KEY"))
  )

{:ok, %{precheck_code: 0, ok?: true}} =
  Client.submit_message(client, TopicId.parse("0.0.9339331"), "audit-event-hash")

Run the live test yourself:

OPERATOR_ID=0.0.x OPERATOR_KEY=0x... mix test --include network

Roadmap

Keccak-256, Ed25519 + ECDSA secp256k1 (Hedera conventions), identifiers, protobuf primitives
TransactionBody + SignedTransaction + Transaction encoding (HCS create / submit)
gRPC client over HTTP/2 (submitMessage, createTopic) — validated live on testnet
Receipt queries (status + sequence number) via gRPC getTransactionReceipts — verified live
Mirror-node REST helpers (Hedera.MirrorNode)
node address book + cross-node retry on transient (BUSY) failures
Token Service (HTS), account create/transfer, crypto transfer
protoc-generated message modules from the canonical Hedera .proto files
hex.pm release

Why field numbers aren't guessed

The transaction layer encodes Hedera protobuf messages whose field numbers must match the canonical schema exactly. Rather than ship unverified guesses, that layer lands together with the gRPC path so it can be validated end-to-end against a real testnet node.

Tests

mix test          # offline; deterministic, no network

License

MIT — see LICENSE.