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key-derivation AI Agent Skill

Quellcode ansehen: b-open-io/bsv-skills

Critical

Installation

npx skills add b-open-io/bsv-skills --skill key-derivation

Installationen

BSV Key Derivation

Two primary approaches for deriving keys on BSV, plus mnemonic support.

Quick Reference

Method	Package	Use Case
Type42 (BRC-42)	`@bsv/sdk`	Modern: privacy-preserving, counterparty derivation
BIP32 (BRC-32)	`@bsv/sdk`	Legacy: HD wallets, sequential paths
Mnemonic	`@bsv/sdk`	Seed phrase to master key conversion

1. Type42 Key Derivation (Recommended)

Modern approach using ECDH shared secrets. Provides enhanced privacy and unlimited key derivation.

Basic Usage

import { PrivateKey, PublicKey } from "@bsv/sdk";

const masterKey = PrivateKey.fromWif("L1...");
const counterpartyPubKey = masterKey.toPublicKey(); // or another party's key

// Derive child key using invoice number
const childKey = masterKey.deriveChild(counterpartyPubKey, "invoice-123");
const childAddress = childKey.toPublicKey().toAddress();

Invoice Number Format (BRC-43)

For protocol-specific derivations, use the format: {securityLevel}-{protocol}-{keyId}

// BAP identity signing key
const bapKey = masterKey.deriveChild(masterKey.toPublicKey(), "1-sigma-identity");

// Encryption key
const encKey = masterKey.deriveChild(masterKey.toPublicKey(), "2-encryption-default");

Counterparty Derivation

Type42 enables deriving shared keys between parties without revealing private keys:

// Alice derives key for Bob
const aliceKey = PrivateKey.fromWif("L1...");
const bobPubKey = PublicKey.fromString("02...");
const sharedKey = aliceKey.deriveChild(bobPubKey, "payment-001");

// Bob derives same address using his private key and Alice's public key
const bobKey = PrivateKey.fromWif("K1...");
const alicePubKey = aliceKey.toPublicKey();
const bobDerived = bobKey.deriveChild(alicePubKey, "payment-001");
// bobDerived.toPublicKey().toAddress() === sharedKey.toPublicKey().toAddress()

Key Advantages

Privacy: ECDH shared secrets prevent address reuse detection
Flexibility: Any string as invoice number (no 2^31 limit)
Auditability: Reveal shared secret to specific parties only
No public derivation: Enhanced security vs BIP32

2. BIP32 HD Key Derivation (Legacy)

Traditional hierarchical deterministic derivation for compatibility.

Basic Usage

import { HD } from "@bsv/sdk";

// From extended private key
const hdKey = HD.fromString("xprv9s21ZrQH143K...");

// Derive child at path
const child = hdKey.derive("m/44'/0'/0'/0/0");
const address = child.pubKey.toAddress();
const privateKey = child.privKey;

Path Format

m = master key
Numbers = child index (0 to 2^31-1)
Apostrophe (') = hardened derivation

// Standard wallet paths
const receiving = hdKey.derive("m/44'/236'/0'/0/0");   // BSV receiving
const change = hdKey.derive("m/44'/236'/0'/1/0");     // BSV change

// BAP identity path
const bapRoot = hdKey.derive("m/424150'/0'/0'");      // 424150 = BAP in decimal

From Mnemonic

import { Mnemonic, HD } from "@bsv/sdk";

const mnemonic = Mnemonic.fromString("word1 word2 word3...");
const seed = mnemonic.toSeed();
const hdKey = HD.fromSeed(seed);

3. Mnemonic to Single Master Key

For Type42, convert mnemonic to a single master key (not extended key):

import { Mnemonic, Hash, PrivateKey, Utils } from "@bsv/sdk";
const { toHex } = Utils;

const mnemonic = Mnemonic.fromString("dial tunnel valid cry exhaust...");
const seed = mnemonic.toSeed();

// SHA256 of seed produces 256-bit private key
const keyBytes = Hash.sha256(seed);
const masterKey = PrivateKey.fromString(toHex(keyBytes), "hex");

// Use with Type42 derivation
const childKey = masterKey.deriveChild(masterKey.toPublicKey(), "bap:0");

This approach:

Maintains familiar mnemonic backup
Produces single key for Type42 (not HD extended key)
Remains compatible with existing BIP39 mnemonics

Choosing Between Methods

Scenario	Recommended
New wallet/identity system	Type42
Privacy-preserving payments	Type42
Counterparty key agreement	Type42
Legacy wallet compatibility	BIP32
Sequential address generation	BIP32
Migration from existing HD wallet	Both (see migration)

BAP Identity Key Derivation

BAP uses a two-level derivation hierarchy:

// Level 1: Member key from path
const memberKey = masterKey.deriveChild(masterKey.toPublicKey(), "bap:0");

// Level 2: Identity signing key using BAP invoice number
const signingKey = memberKey.deriveChild(memberKey.toPublicKey(), "1-sigma-identity");
const signingAddress = signingKey.toPublicKey().toAddress();

For BIP32 legacy:

const memberHD = hdKey.derive("m/424150'/0'/0'/0/0/0");
// Then apply Type42 for signing key
const signingKey = memberHD.privKey.deriveChild(memberHD.pubKey, "1-sigma-identity");

Security Considerations

Never expose master keys: Derive child keys for operations
Use hardened paths for BIP32 when privacy matters (apostrophe)
Type42 prevents public derivation: Cannot derive child public keys from parent public key alone
Invoice numbers are not secret: They can be shared

bsv-bap Library

The bsv-bap library implements Type42 with BRC-43 invoice numbers for BAP identities:

import { BAP } from "bsv-bap";
import { PrivateKey } from "@bsv/sdk";

const bap = new BAP({ rootPk: PrivateKey.fromRandom().toWif() });
const identity = bap.newId("Alice");

// Signing key derived with "1-sigma-identity"
const { address, signature } = identity.signMessage(messageBytes);

// Friend encryption key derived with "2-friend-{sha256(friendBapId)}"
const friendPubKey = identity.getEncryptionPublicKeyWithSeed(friendBapId);
const ciphertext = identity.encryptWithSeed("secret", friendBapId);

A CLI is also available: bun add -g bsv-bap (see create-bap-identity skill).

Official Specifications

All BSV key derivation standards are documented at:

https://bsv.brc.dev/key-derivation

Key specifications:

BRC-42: Type42 key derivation scheme
BRC-32: BIP32 HD key derivation
BRC-43: Security levels, protocol IDs, key IDs
BRC-69: Revealing key linkages
BRC-72: Protecting key linkage information

Additional Resources

Reference Files

references/brc-42-type42.md - Complete Type42 specification and advanced patterns
references/brc-32-bip32.md - BIP32 legacy derivation details
references/bap-derivation.md - BAP identity key derivation patterns and migration

Examples

examples/type42-derivation.ts - Type42 counterparty key derivation
examples/bip32-wallet.ts - BIP32 HD wallet with standard paths
examples/mnemonic-to-type42.ts - Convert mnemonic to Type42 master key

Installationen

Installationen 21

Globales Ranking #601 von 601

Sicherheitsprüfung

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Quellcode ansehen

b-open-io/bsv-skills

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So verwenden Sie diesen Skill

Install key-derivation by running npx skills add b-open-io/bsv-skills --skill key-derivation in your project directory. Führen Sie den obigen Installationsbefehl in Ihrem Projektverzeichnis aus. Die Skill-Datei wird von GitHub heruntergeladen und in Ihrem Projekt platziert.

Keine Konfiguration erforderlich. Ihr KI-Agent (Claude Code, Cursor, Windsurf usw.) erkennt installierte Skills automatisch und nutzt sie als Kontext bei der Code-Generierung.

Der Skill verbessert das Verständnis Ihres Agenten für key-derivation, und hilft ihm, etablierte Muster zu befolgen, häufige Fehler zu vermeiden und produktionsreifen Code zu erzeugen.

Was Sie erhalten

Skills sind Klartext-Anweisungsdateien — kein ausführbarer Code. Sie kodieren Expertenwissen über Frameworks, Sprachen oder Tools, das Ihr KI-Agent liest, um seine Ausgabe zu verbessern. Das bedeutet null Laufzeit-Overhead, keine Abhängigkeitskonflikte und volle Transparenz: Sie können jede Anweisung vor der Installation lesen und prüfen.

Kompatibilität

Dieser Skill funktioniert mit jedem KI-Coding-Agenten, der das skills.sh-Format unterstützt, einschließlich Claude Code (Anthropic), Cursor, Windsurf, Cline, Aider und anderen Tools, die projektbezogene Kontextdateien lesen. Skills sind auf Transportebene framework-agnostisch — der Inhalt bestimmt, für welche Sprache oder welches Framework er gilt.

Data sourced from the skills.sh registry and GitHub. Install counts and security audits are updated regularly.

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key-derivation AI Agent Skill

BSV Key Derivation

Quick Reference

1. Type42 Key Derivation (Recommended)

Basic Usage

Invoice Number Format (BRC-43)

Counterparty Derivation

Key Advantages

2. BIP32 HD Key Derivation (Legacy)

Basic Usage

Path Format

From Mnemonic

3. Mnemonic to Single Master Key

Choosing Between Methods

BAP Identity Key Derivation

Security Considerations

bsv-bap Library

Official Specifications

Additional Resources

Reference Files

Examples

Installationen

Sicherheitsprüfung

Quellcode ansehen

Power your AI Agents with the best open-source models.

So verwenden Sie diesen Skill

Was Sie erhalten

Kompatibilität

Chat with 100+ AI Models in one App.

Power your AI Agents with
the best open-source models.