Signing Skill

Provides cryptographic message signing for the Stacks and Bitcoin ecosystems. Four signing standards are supported:

• SIP-018 — Structured Clarity data signing. Signatures are verifiable both off-chain and by on-chain smart contracts via secp256k1-recover?.
• Stacks messages — SIWS-compatible plain-text signing. Used for wallet authentication and proving address ownership.
• Bitcoin messages — BIP-137/BIP-322 hybrid. BIP-137 for legacy (1...) and wrapped SegWit (3...) addresses; BIP-322 "simple" for native SegWit (bc1q) and Taproot (bc1p) addresses. Compatible with Electrum, Bitcoin Core, and modern wallets.
• Schnorr (BIP-340) — Taproot-native signing over raw 32-byte digests. Used for Taproot script-path spending, multisig coordination, and OP_CHECKSIGADD witness assembly.
• Nostr events (NIP-06) — Sign Nostr event objects using the NIP-06 derived key (m/44'/1237'/0'/0/0) by default, or from a wallet key path via keySource.

Usage

bun run signing/signing.ts <subcommand> [options]

Subcommands

sip018-sign

Sign structured Clarity data using the SIP-018 standard. The domain binding (name + version + chain-id) prevents cross-app and cross-chain replay attacks. Requires an unlocked wallet.

bun run signing/signing.ts sip018-sign \
  --message '{"amount":{"type":"uint","value":100}}' \
  --domain-name "My App" \
  --domain-version "1.0.0"

Options:

• --message (required) — Structured data as a JSON string. Use type hints for explicit Clarity types:
  • {"type":"uint","value":100} → uint
  • {"type":"int","value":-50} → int
  • {"type":"principal","value":"SP..."} → principal
  • {"type":"ascii","value":"hello"} → string-ascii
  • {"type":"utf8","value":"hello"} → string-utf8
  • {"type":"buff","value":"0x1234"} → buff
  • {"type":"bool","value":true} → bool
  • {"type":"none"} → none
  • {"type":"some","value":...} → (some ...)
  • {"type":"list","value":[...]} → list
  • {"type":"tuple","value":{...}} → tuple
  • Implicit: string → string-utf8, number → int, boolean → bool, null → none
• --domain-name + --domain-version (required together) — Flat CLI domain fields
• --domain (alternative) — MCP-style JSON object: {"name":"My App","version":"1.0.0"} (optional chainId)

Output:

{
  "success": true,
  "signature": "abc123...",
  "signatureFormat": "RSV (65 bytes hex)",
  "signer": "SP...",
  "network": "testnet",
  "chainId": 2147483648,
  "hashes": {
    "message": "...",
    "domain": "...",
    "encoded": "...",
    "verification": "...",
    "prefix": "0x534950303138"
  },
  "domain": { "name": "My App", "version": "1.0.0", "chainId": 2147483648 },
  "verificationNote": "Use sip018-verify with the 'verification' hash..."
}

sip018-verify

Verify a SIP-018 signature and recover the signer's Stacks address. Provide the verification hash from sip018-sign or sip018-hash.

bun run signing/signing.ts sip018-verify \
  --message-hash <verificationHash> \
  --signature <rsv65BytesHex> \
  [--expected-signer <address>]

Options:

• --message-hash (required) — The SIP-018 verification hash (from sip018-sign/sip018-hash)
• --signature (required) — Signature in RSV format (65 bytes hex)
• --expected-signer (optional) — Expected signer address to verify against

Output:

{
  "success": true,
  "recoveredPublicKey": "03...",
  "recoveredAddress": "SP...",
  "network": "testnet",
  "verification": {
    "expectedSigner": "SP...",
    "isValid": true,
    "message": "Signature is valid for the expected signer"
  }
}

sip018-hash

Compute the SIP-018 message hash without signing. Returns all hash components needed for off-chain or on-chain verification. Does not require an unlocked wallet.

bun run signing/signing.ts sip018-hash \
  --message '{"amount":{"type":"uint","value":100}}' \
  --domain-name "My App" \
  --domain-version "1.0.0" \
  [--chain-id <id>]

Options:

• --message (required) — Structured data as a JSON string (same format as sip018-sign)
• --domain-name + --domain-version (required together) — Flat CLI domain fields
• --domain (alternative) — MCP-style JSON object: {"name":"My App","version":"1.0.0"} (optional chainId)
• --chain-id (optional) — Chain ID override (takes precedence over domain.chainId)

Output:

{
  "success": true,
  "hashes": {
    "message": "...",
    "domain": "...",
    "encoded": "...",
    "verification": "..."
  },
  "hashConstruction": {
    "prefix": "0x534950303138",
    "formula": "verification = sha256(prefix || domainHash || messageHash)"
  },
  "domain": { "name": "My App", "version": "1.0.0", "chainId": 2147483648 },
  "clarityVerification": {
    "example": "(secp256k1-recover? (sha256 encoded-data) signature)"
  }
}

stacks-sign

Sign a plain text message using the Stacks message signing format. The message is prefixed with \x17Stacks Signed Message:\n before hashing (SIWS-compatible). Requires an unlocked wallet.

bun run signing/signing.ts stacks-sign --message "Hello, Stacks!"

Options:

• --message (required) — Plain text message to sign

Output:

{
  "success": true,
  "signature": "abc123...",
  "signatureFormat": "RSV (65 bytes hex)",
  "signer": "SP...",
  "network": "testnet",
  "message": {
    "original": "Hello, Stacks!",
    "prefix": "\u0017Stacks Signed Message:\n",
    "prefixHex": "...",
    "hash": "..."
  },
  "verificationNote": "Use stacks-verify with the original message and signature to verify."
}

stacks-verify

Verify a Stacks message signature and recover the signer's Stacks address. Compatible with SIWS authentication flows.

bun run signing/signing.ts stacks-verify \
  --message "Hello, Stacks!" \
  --signature <rsv65BytesHex> \
  [--expected-signer <address>]

Options:

• --message (required) — The original plain text message that was signed
• --signature (required) — Signature in RSV format (65 bytes hex)
• --expected-signer (optional) — Expected signer Stacks address

Output:

{
  "success": true,
  "signatureValid": true,
  "recoveredPublicKey": "03...",
  "recoveredAddress": "SP...",
  "network": "testnet",
  "message": {
    "original": "Hello, Stacks!",
    "prefix": "\u0017Stacks Signed Message:\n",
    "hash": "..."
  },
  "verification": {
    "expectedSigner": "SP...",
    "signerMatches": true,
    "isFullyValid": true,
    "message": "Signature is valid and matches expected signer"
  }
}

btc-sign

Sign a plain text message using Bitcoin message signing. Automatically selects the signing format based on address type: BIP-137 (65-byte compact signature) for legacy (1...) and wrapped SegWit (3...) addresses; BIP-322 "simple" (witness-serialized) for native SegWit (bc1q) and Taproot (bc1p) addresses. Compatible with Electrum, Bitcoin Core, and modern wallets. Requires an unlocked wallet with Bitcoin keys.

bun run signing/signing.ts btc-sign --message "Hello, Bitcoin!"

Options:

• --message (required) — Plain text message to sign

Output:

{
  "success": true,
  "signature": "abc123...",
  "signatureBase64": "...",
  "signatureFormat": "BIP-137 (65 bytes: 1 header + 32 r + 32 s)",
  "signer": "bc1q...",
  "network": "mainnet",
  "addressType": "P2WPKH (native SegWit)",
  "message": {
    "original": "Hello, Bitcoin!",
    "prefix": "\u0018Bitcoin Signed Message:\n",
    "prefixHex": "...",
    "formattedHex": "...",
    "hash": "..."
  },
  "header": { "value": 39, "recoveryId": 0, "addressType": "P2WPKH (native SegWit)" },
  "verificationNote": "Use btc-verify with the original message and signature to verify."
}

btc-verify

Verify a Bitcoin message signature (BIP-137 or BIP-322) and recover the signer's Bitcoin address. Automatically detects the format: BIP-137 (65-byte compact, hex 130 chars or base64 88 chars) for legacy/wrapped-SegWit addresses, and BIP-322 "simple" (witness-serialized, base64) for native SegWit (bc1q) and Taproot (bc1p) addresses.

bun run signing/signing.ts btc-verify \
  --message "Hello, Bitcoin!" \
  --signature <hexOrBase64Sig> \
  [--expected-signer <btcAddress>]

Options:

• --message (required) — The original plain text message that was signed
• --signature (required) — Bitcoin signature: BIP-137 (65 bytes as hex [130 chars] or base64 [88 chars]) for legacy/wrapped-SegWit, or BIP-322 "simple" (witness-serialized, base64) for bc1q/bc1p addresses
• --expected-signer (optional) — Expected signer Bitcoin address to verify against

Output:

{
  "success": true,
  "signatureValid": true,
  "recoveredPublicKey": "03...",
  "recoveredAddress": "bc1q...",
  "network": "mainnet",
  "message": { "original": "Hello, Bitcoin!", "prefix": "...", "hash": "..." },
  "header": { "value": 39, "recoveryId": 0, "addressType": "P2WPKH (native SegWit)" },
  "verification": {
    "expectedSigner": "bc1q...",
    "signerMatches": true,
    "isFullyValid": true,
    "message": "Signature is valid and matches expected signer"
  }
}

schnorr-sign-digest

Sign a raw 32-byte digest with Schnorr (BIP-340) using the wallet's Taproot private key. Use for Taproot script-path spending, multisig coordination, or any case where you need a BIP-340 Schnorr signature over a pre-computed hash (e.g., BIP-341 sighash). Includes a blind-signing safety gate — the first call without --confirm-blind-sign returns the digest for review. Requires an unlocked wallet with Taproot keys.

bun run signing/signing.ts schnorr-sign-digest \
  --digest <64-char-hex> \
  [--aux-rand <64-char-hex>] \
  [--confirm-blind-sign]

Options:

• --digest (required) — 32-byte hex-encoded digest to sign (e.g., BIP-341 transaction sighash)
• --aux-rand (optional) — 32-byte hex auxiliary randomness for BIP-340 (improves side-channel resistance)
• --confirm-blind-sign (optional) — Set to confirm you have reviewed the digest and accept blind-signing risk. Without this flag, returns a warning with the digest for review.

Output (without --confirm-blind-sign):

{
  "warning": "schnorr-sign-digest signs a raw 32-byte digest...",
  "digestToReview": "abc123...",
  "instructions": "Review the digest above. If you trust its origin..."
}

Output (with --confirm-blind-sign):

{
  "success": true,
  "signature": "abc123...",
  "publicKey": "def456...",
  "address": "bc1p...",
  "network": "mainnet",
  "signatureFormat": "BIP-340 Schnorr (64 bytes)",
  "publicKeyFormat": "x-only (32 bytes)",
  "note": "For Taproot script-path spending, append sighash type byte..."
}

schnorr-verify-digest

Verify a BIP-340 Schnorr signature over a 32-byte digest. Takes the digest, signature, and x-only public key, returns whether the signature is valid. Use for verifying Taproot signatures from other agents in multisig coordination.

bun run signing/signing.ts schnorr-verify-digest \
  --digest <64-char-hex> \
  --signature <128-char-hex> \
  --public-key <64-char-hex>

Options:

• --digest (required) — 32-byte hex-encoded digest that was signed
• --signature (required) — 64-byte hex-encoded BIP-340 Schnorr signature
• --public-key (required) — 32-byte hex-encoded x-only public key of the signer

Output:

{
  "success": true,
  "isValid": true,
  "digest": "abc123...",
  "signature": "def456...",
  "publicKey": "789abc...",
  "message": "Signature is valid for the given digest and public key",
  "note": "BIP-340 Schnorr verification. Use for validating signatures in Taproot multisig coordination."
}

nostr-sign-event

Sign a Nostr event object (NIP-01 format) using the wallet's Nostr key. By default the key is derived via NIP-06 (m/44'/1237'/0'/0/0) from the wallet mnemonic, producing an npub that matches NIP-06 compliant Nostr clients (e.g. Amethyst, Damus, Snort). Requires an unlocked wallet.

bun run signing/signing.ts nostr-sign-event \
  --event '{"kind":1,"created_at":1700000000,"tags":[],"content":"Hello, Nostr!"}' \
  [--key-source nostr|taproot|segwit]

Options:

• --event (required) — Nostr event JSON object (NIP-01 format). Fields id, pubkey, and sig are computed and returned; do not include them in the input.
• --key-source (optional, default: "nostr") — Which wallet key to use for signing:
  • "nostr" (default) — NIP-06 derived key (m/44'/1237'/0'/0/0). Use this for new identities and compatibility with all NIP-06 Nostr clients.
  • "taproot" — BIP-86 Taproot key (m/86'/0'/0'/0/0). Use if you already have an existing Nostr identity on your Taproot key.
  • "segwit" — BIP-84 native SegWit key (m/84'/0'/0'/0/0). Use if you already have an existing Nostr identity on your SegWit key.

Output:

{
  "success": true,
  "event": {
    "id": "abc123...",
    "pubkey": "def456...",
    "created_at": 1700000000,
    "kind": 1,
    "tags": [],
    "content": "Hello, Nostr!",
    "sig": "789abc..."
  },
  "npub": "npub1...",
  "keySource": "nostr",
  "derivationPath": "m/44'/1237'/0'/0/0",
  "note": "Key derived via NIP-06. npub matches NIP-06 compliant Nostr clients."
}

Key derivation note: The default "nostr" source uses NIP-06 (m/44'/1237'/0'/0/0), the standard Nostr derivation path defined in the NIP-06 spec. Agents should use this default for all Nostr interactions. The keySource override is only needed when an existing Nostr identity was previously established on a different key path.

Signing Standards Reference

Notes

• SIP-018 signing and Stacks signing require an unlocked wallet (bun run wallet/wallet.ts unlock)
• BTC signing additionally requires Bitcoin keys (automatically present in managed wallets)
• Schnorr signing requires Taproot keys (automatically derived in managed wallets)
• sip018-hash, both *-verify subcommands, and schnorr-verify-digest do NOT require an unlocked wallet
• All ECDSA signatures use the secp256k1 curve; Schnorr uses BIP-340 (x-only pubkeys, 64-byte sigs)
• SIP-018 chain IDs: mainnet = 1, testnet = 2147483648 (0x80000000)