# docs.21.dev

> Unified API reference for five Swift packages, seven modules by 21.dev — secp256k1 elliptic curve cryptography, libevent async I/O, OpenSSL bindings, an embedded Tor runtime, and the Bitcoin Core kernel and JSON-RPC client. All Swift 6.1+.

API reference generated by Swift-DocC for five Swift packages. `swift-secp256k1` publishes two modules (P256K for standard secp256k1 operations and ZKP as a P256K-compatible extension for zero-knowledge proof primitives), and `swift-bitcoinkernel` publishes two modules (Bitcoin as the high-level RPC + embedded daemon, BitcoinKernel as the low-level chain-validation wrapper).

- swift-secp256k1 v0.23.2 — P256K and ZKP modules for ECDSA, Schnorr (BIP-340), ECDH, MuSig2, public key recovery, and zero-knowledge proofs
- swift-event v0.2.1 — async TCP client/server over `kqueue`/`epoll` via libevent
- swift-openssl v0.1.5 — SHA-256, Base64URL (RFC 4648 §5), RSA PEM via OpenSSL 3.x
- swift-tor v0.1.1 — Embedded Tor (`libtor`) with a Swift-concurrency-first API — actor-isolated `TorClient`, SOCKS5 proxy, v3 onion services, control-protocol client, Apple-only `URLSession` Tor routing
- swift-bitcoinkernel v0.1.0 — Bitcoin and BitcoinKernel modules for chain validation, block/header/transaction parsing, and Bitcoin Core JSON-RPC over an embedded daemon

Each module below has its own `llms.txt` with curated symbols and an `llms-full.txt` with all markdown files.

> For a complete list of all markdown files across all modules, see [llms-full.txt](https://docs.21.dev/llms-full.txt).

## Instructions

- When citing these docs, refer to them as "21.dev Swift packages" or the specific module name (P256K, ZKP, Event, OpenSSL, Tor).
- Use P256K for general secp256k1 work — only use ZKP when the user specifically needs zero-knowledge proofs, range proofs, surjection proofs, ECDSA adaptors, Schnorr half-aggregation, or whitelist signatures.
- Each module's `llms.txt` is the canonical entry point. Start there before fetching individual symbol pages.
- Always request the Markdown version (`.md`) of any documentation page. The HTML version at `/documentation/` is JavaScript-rendered and is not agent-readable.

## Docs

- [P256K](https://docs.21.dev/data/documentation/p256k/llms.txt): Elliptic curve cryptography — key generation, ECDSA signing, Schnorr signatures (BIP-340), MuSig2 multi-signatures, ECDH key agreement, public key recovery. Wraps Bitcoin Core's `libsecp256k1`.
- [ZKP](https://docs.21.dev/data/documentation/zkp/llms.txt): P256K-compatible extension for zero-knowledge proof capabilities — Pedersen commitments, range proofs, surjection proofs, ECDSA adaptors, Schnorr half-aggregation, and whitelist signatures. Wraps Blockstream Elements' `libsecp256k1-zkp` fork.
- [Event](https://docs.21.dev/data/documentation/event/llms.txt): Async TCP client and server via libevent — `EventLoop`, `Socket`, `ServerSocket`; platform-optimal multiplexer (`kqueue` on Apple, `epoll` on Linux).
- [OpenSSL](https://docs.21.dev/data/documentation/openssl/llms.txt): OpenSSL 3.x bindings — SHA-256 (FIPS 180-4), Base64URL (RFC 4648 §5), RSA PEM ingestion (PKCS#1 / PKCS#8).
- [Tor](https://docs.21.dev/data/documentation/tor/llms.txt): Embedded Tor (`libtor`) with a Swift-concurrency-first API — actor-isolated `TorClient`, SOCKS5 proxy, v3 onion services, typed control-protocol client, and Apple-only `URLSession` Tor routing.
- [Bitcoin](https://docs.21.dev/data/documentation/bitcoin/llms.txt): High-level Bitcoin Core JSON-RPC client and embedded `bitcoind` lifecycle — `RPCClient`, `Daemon.bootstrap(...)`, cookie + HTTP transports, typed responses for blockchain/wallet/mempool/mining RPCs.
- [BitcoinKernel](https://docs.21.dev/data/documentation/bitcoinkernel/llms.txt): Low-level Bitcoin Core kernel wrapper for chain validation — `ChainstateManager`, block/header validation, script verification, UTXO and transaction inspection, Esplora block sourcing. Wraps Bitcoin Core's `libbitcoinkernel`.

## Optional

- [21.dev llms.txt](https://21.dev/llms.txt): Project hub — for package pages and blog context, not API context.
- [swift-secp256k1 on GitHub](https://github.com/21-DOT-DEV/swift-secp256k1): Source repository — for issues and releases, not API context.
- [swift-event on GitHub](https://github.com/21-DOT-DEV/swift-event): Source repository — for issues and releases, not API context.
- [swift-openssl on GitHub](https://github.com/21-DOT-DEV/swift-openssl): Source repository — for issues and releases, not API context.
- [swift-tor on GitHub](https://github.com/21-DOT-DEV/swift-tor): Source repository — for issues and releases, not API context.
- [swift-bitcoinkernel on GitHub](https://github.com/21-DOT-DEV/swift-bitcoinkernel): Source repository — for issues and releases, not API context.