@kinecosystem/kin-base/lib/base58.js

Low level Kin support library

"use strict";

var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };

exports.decodeBase58Check = decodeBase58Check;
Object.defineProperty(exports, "__esModule", {
  value: true
});

var bs58 = _interopRequire(require("./vendor/bs58"));

var isUndefined = _interopRequire(require("lodash/isUndefined"));

var hash = require("./hashing").hash;

var verifyChecksum = require("./util/checksum").verifyChecksum;

var versionBytes = {
  accountId: 0, // decimal 0
  none: 1, // decimal 1
  seed: 33 };

function decodeBase58Check(versionByteName, encoded) {
  var decoded = bs58.decode(encoded);
  var versionByte = decoded[0];
  var payload = decoded.slice(0, decoded.length - 4);
  var data = payload.slice(1);
  var checksum = decoded.slice(decoded.length - 4);

  var expectedVersion = versionBytes[versionByteName];

  if (isUndefined(expectedVersion)) {
    throw new Error("" + versionByteName + " is not a valid version byte name.  expected one of \"accountId\", \"seed\", or \"none\"");
  }

  if (versionByte !== expectedVersion) {
    throw new Error("invalid version byte.  expected " + expectedVersion + ", got " + versionByte);
  }

  var expectedChecksum = calculateChecksum(payload);

  if (!verifyChecksum(expectedChecksum, checksum)) {
    throw new Error("invalid checksum");
  }

  if (versionByteName === "accountId" && decoded.length !== 37) {
    throw new Error("Decoded address length is invalid. Expected 37, got " + decoded.length);
  }

  return Buffer.from(data);
}

function calculateChecksum(payload) {
  var inner = hash(payload);
  var outer = hash(inner);
  return outer.slice(0, 4);
}
// decimal 33