unisat-dev-docs

Sign Message

signMessage

unisat.signMessage(msg[, type])

Sign a message with the current account’s private key.

Parameters

• msg - string: a string to sign

• type - string: (Optional) “ecdsa”

  “bip322-simple”. default is “ecdsa”

Returns

• Promise - string: the signature (Base64 encoded).

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Signature Types

ECDSA (Default)

The default signature type uses RFC6979 Deterministic ECDSA with Bitcoin’s standard message signing format.

How it works:

1. Message Hashing: The message is prefixed with "Bitcoin Signed Message:\n" and double SHA256 hashed:

   hash = SHA256(SHA256(varint(prefix.length) + prefix + varint(msg.length) + msg))
   

2. Deterministic Signing (RFC6979): Instead of using a random nonce k, the signature uses HMAC-DRBG to deterministically generate k from the private key and message hash. This ensures:
   • Same private key + same message = same signature (deterministic)
   • No risk of private key leakage due to weak random number generation
3. Output Format: Bitcoin compact signature format (65 bytes, Base64 encoded)
   • 1 byte header: 27 + recovery_id + 4 (for compressed public key)
   • 32 bytes r value
   • 32 bytes s value (low-S, BIP-62/BIP-146 compliant)

Supported Address Types: P2PKH, P2SH-P2WPKH, P2WPKH, P2TR

BIP-322 Simple

BIP-322 is a generic message signing standard that works with all Bitcoin address types, including Taproot (P2TR).

How it works:

1. Creates a virtual “to_sign” transaction that spends from a “to_spend” transaction
2. The witness/scriptSig of the “to_sign” transaction serves as the signature
3. Supports all address types natively, including P2TR with Schnorr signatures

Output Format: Base64 encoded witness stack

Recommended for: Taproot addresses (P2TR) or when cross-wallet compatibility is required.

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Example

// sign by ecdsa
try {
    let res = await window.unisat.signMessage("abcdefghijk123456789");
    console.log(res)
} catch (e) {
    console.log(e);
}

> G+LrYa7T5dUMDgQduAErw+i6ebK4GqTXYVWIDM+snYk7Yc6LdPitmaqM6j+iJOeID1CsMXOJFpVopvPiHBdulkE=

// verify by ecdsa
import { verifyMessage } from "@unisat/wallet-utils";
const pubkey = "026887958bcc4cb6f8c04ea49260f0d10e312c41baf485252953b14724db552aac";
const message = "abcdefghijk123456789";
const signature = "G+LrYa7T5dUMDgQduAErw+i6ebK4GqTXYVWIDM+snYk7Yc6LdPitmaqM6j+iJOeID1CsMXOJFpVopvPiHBdulkE=";
const result = verifyMessage(pubkey,message,signature);
console.log(result);

> true

// sign by bip322-simple
try {
    let res = await window.unisat.signMessage("abcdefghijk123456789","bip322-simple");
    console.log(res)
} catch (e) {
    console.log(e);
}

> AkcwRAIgeHUcjr0jODaR7GMM8cenWnIj0MYdGmmrpGyMoryNSkgCICzVXWrLIKKp5cFtaCTErY7FGNXTFe6kuEofl4G+Vi5wASECaIeVi8xMtvjATqSSYPDRDjEsQbr0hSUpU7FHJNtVKqw=