@kazeblockchain/krypton-js/src/wallet/multisig.js

Javascript libraries for kaze wallet using https://github.com/kazechainio/kazewallet/blob/master/js/wallet.js as the original source.

import { OpCode, ScriptBuilder } from '../sc'
import { reverseHex, StringStream } from '../utils'
import { isPublicKey } from './verify'

/**
 * @param {number} signingThreshold
 * @param {string[]} keys
 * @return {string} verificationScript
 */
export function constructMultiSigVerificationScript (signingThreshold, keys) {
  if (signingThreshold > keys.length) {
    throw new Error(
      'signingThreshold must be smaller than or equal to number of keys'
    )
  }

  const ss = new ScriptBuilder()
  ss.emitPush(signingThreshold)
  keys.forEach(k => {
    if (!isPublicKey(k, true)) {
      throw new Error(`${k} is not a valid encoded public key`)
    }
    ss.emitPush(k)
  })
  ss.emitPush(keys.length)
  ss.emit(OpCode.CHECKMULTISIG)
  return ss.str
}

/**
 * Returns the list of public keys found in the verification script.
 * @param {string} verificationScript Verification Script of an Account.
 */
export function getPublicKeysFromVerificationScript (verificationScript) {
  const ss = new StringStream(verificationScript)
  const keys = []
  while (!ss.isEmpty()) {
    const byte = ss.read()
    if (byte === '21') {
      keys.push(ss.read(33))
    }
  }
  return keys
}

/**
 * Returns the number of signatures required for signing for a verification Script.
 * @param {string} verificationScript Verification Script of a multi-sig Account.
 * @returns {number}
 */
export function getSigningThresholdFromVerificationScript (verificationScript) {
  const checkSigOpCode = verificationScript.slice(
    verificationScript.length - 2
  )
  if (checkSigOpCode === 'ac') {
    return 1
  } else if (checkSigOpCode === 'ae') {
    const ss = new StringStream(verificationScript)
    const byte = parseInt(ss.peek(), 16)
    if (byte < 80) {
      const hexNum = reverseHex(ss.readVarBytes())
      return parseInt(hexNum, 16)
    } else {
      return parseInt(ss.read(), 16) - 80
    }
  } else {
    throw new Error(
      'VerificationScript does not call CHECKSIG or CHECKMULTISIG.'
    )
  }
}

/**
 * Extract signatures from invocationScript
 * @param {string} invocationScript InvocationScript of a Witness.
 * @returns {string[]}
 */
export function getSignaturesFromInvocationScript (invocationScript) {
  const ss = new StringStream(invocationScript)
  const sigs = []
  while (!ss.isEmpty()) {
    const byte = parseInt(ss.peek(), 16)
    if (byte > 80) {
      continue
    } else if (byte === 4 * 16) {
      sigs.push(ss.readVarBytes())
    }
  }
  return sigs
}