Styx Protocol — ERCs Overview

Covenant’s cryptographic primitives are not proprietary extensions — they are standardized through four Ethereum Improvement Proposals collectively called the Styx Protocol. Each ERC defines an on-chain interface that any EVM-compatible contract can implement, whether written in Covenant, Solidity, or Vyper.

The Four Standards

All four ERCs are currently in Draft status. The target for Final status is Q4 2026, with ERC-8227 (FHE Tokens) scheduled to move to Review first due to its broader applicability.

What Is an ERC?

An Ethereum Request for Comment is a proposal that defines a standard interface for contracts on the EVM. Well-known examples: ERC-20 (fungible tokens), ERC-721 (NFTs), ERC-4337 (account abstraction).

ERCs become standards through community review, implementation, and adoption. Covenant implements all four Styx ERCs natively — when you write encrypted token in Covenant, the compiler generates an ERC-8227-compliant contract automatically.

Implementation Profiles

The Styx specification defines five compliance profiles (CL1–CL5) to allow incremental adoption:

Covenant V0.7 contracts compile to CL5 by default when using all features. You can constrain the output profile using the --compliance-profile flag:

covenant build --compliance-profile CL2 ./src/Payroll.cvt

How ERCs Map to Covenant Constructs

Covenant source                →  ERC standard         →  EVM precompile
─────────────────────────────────────────────────────────────────────────
encrypted<uint256>             →  ERC-8227 §3.1         →  0x0f (fhe_encrypt)
fhe_add(a, b)                  →  ERC-8227 §3.2         →  0x10 (fhe_add)
reveal field to caller         →  ERC-8227 §3.4         →  0x13 (fhe_decrypt_auth)
amnesia { destroy(secret) }    →  ERC-8228 §2           →  0x20 (amnesia_destroy)
ceremony { ... }               →  ERC-8228 §4           →  0x21–0x24 (phase management)
zk_verify(proof, signal)       →  ERC-8229 §2           →  0x30 (zk_verify)
@prove_offchain                →  ERC-8229 §5           →  (off-chain WASM circuit)
pq_key type                    →  ERC-8231 §2           →  0x40 (pq_register)
@pq_signed(key)                →  ERC-8231 §3           →  0x41 (pq_verify)

Standardization Timeline

Relation to the Covenant Compiler

The Covenant compiler (V0.7) generates ERC-8227/8228/8229/8231 compliant bytecode without requiring any manual ABI wiring. If you write:

encrypted token ConfidentialUSDC {
    name: "Confidential USDC"
    symbol: "cUSDC"
    decimals: 6
}

The compiler generates:

• The ERC-8227 IConfidentialToken interface implementation
• The correct precompile call sequences
• The CBOR metadata blob with ERC ID annotations

If you’re building tooling (block explorers, wallets, bridge relayers) that needs to interact with Covenant contracts without the Covenant compiler, the ERC specifications are your source of truth.

See Also

• ERC-8227 — Encrypted Tokens
• ERC-8228 — Cryptographic Amnesia
• ERC-8229 — FHE Verification Standard
• ERC-8231 — Post-Quantum Key Registry
• Glossary: FHE, ZK proofs, PQ signatures