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Protocols

Chromia's protocol stack defines how data is serialized, transactions are executed, accounts and tokens are managed, and chains exchange information. Each layer builds on the previous one so developers can compose rich dapps without reinventing infrastructure.

Data and transaction encoding​

  • Generic Transfer Value (GTV) — GTV is the ASN.1 DER serialization scheme Postchain uses for every primitive and composite type. Tables in the protocol reference map each Rell type to its GTV representation for operation inputs, query inputs, and outputs, and highlight the stricter type checking introduced in Rell 0.13.9.
  • Generic Transaction Protocol (GTX) — GTX wraps GTV to define how transactions are constructed. A GTX body includes the blockchain RID, a list of operations (each with a name and GTV-encoded arguments), and the signer set. It natively supports multi-signature transactions, standard ASN.1 serialization, and atomic execution so either all operations succeed or none do.

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Accounts and tokens with FT4​

The FT4 library is Chromia's reference implementation for account-centric token management:

  • Asset registration — Define name, ticker, decimals, and minting logic for on-chain assets, or register assets across chains so balances can move between chain A and chain B before bridging outward.
  • Account lifecycle — Accounts resemble Web2-style profiles backed by key pairs; they must be explicitly registered before receiving transfers, and developers can plug in their own business logic for approvals, descriptors, and multi-key setups.
  • Wallet compatibility — Users can authenticate with Chromia Vault or reuse existing Ethereum/Binance addresses, and FT4 exposes the hooks needed to bridge balances through Chromia's EVM interoperability stack.

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Cross-chain messaging​

  • ICMF (Inter-chain Messaging Facility) — Within a single dapp cluster, ICMF implements event-style messaging so one blockchain can emit events that another subscribes to and reacts upon. It underpins intra-cluster asset transfers, workflow orchestration, and state synchronization.
  • ICCF (Inter-chain Confirmation Facility) — When chains live in different clusters, ICCF acts as a client that submits a transaction on the source chain, waits for finality, constructs a proof, and presents it to the destination chain. Typical uses include cross-cluster asset transfers, multi-cluster governance, and integrations with external networks.

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To dive deeper into any protocol, explore the full Protocols section in Fundamentals, or follow the linked use cases for hands-on examples.