theseus/bundled-addons/bchwallet/lib/base58check.js

// Base58Check encode/decode for Tron addresses (0x41 || H160 || sha256d[:4]).
// Bitcoin-style base58 alphabet; the caller supplies the raw 21-byte payload
// (version byte first) so this module knows nothing about Tron itself.
const ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
const INDEX = new Int8Array(128).fill(-1);
for (let i = 0; i < ALPHABET.length; i++) INDEX[ALPHABET.charCodeAt(i)] = i;

module.exports = function makeBase58Check({ sha256 }) {
  function encodeBase58(bytes) {
    let zeros = 0;
    while (zeros < bytes.length && bytes[zeros] === 0) zeros++;
    // Convert base-256 → base-58 by repeated division.
    const b58 = new Uint8Array(Math.ceil(bytes.length * 138 / 100 + 1));
    let length = 0;
    for (let i = zeros; i < bytes.length; i++) {
      let carry = bytes[i];
      let j = 0;
      for (let k = b58.length - 1; (carry !== 0 || j < length) && k >= 0; k--, j++) {
        carry += (b58[k] << 8) >>> 0;
        b58[k] = carry % 58;
        carry = (carry / 58) | 0;
      }
      length = j;
    }
    // Skip leading zero-bytes in the base58 buffer, then prepend '1' per leading zero-byte in input.
    let it = b58.length - length;
    while (it < b58.length && b58[it] === 0) it++;
    let out = "";
    for (let i = 0; i < zeros; i++) out += ALPHABET[0];
    for (; it < b58.length; it++) out += ALPHABET[b58[it]];
    return out;
  }

  function decodeBase58(str) {
    if (typeof str !== "string" || str.length === 0) throw new Error("base58: empty input");
    let zeros = 0;
    while (zeros < str.length && str[zeros] === ALPHABET[0]) zeros++;
    const out = new Uint8Array(Math.ceil(str.length * 733 / 1000 + 1));
    let length = 0;
    for (let i = zeros; i < str.length; i++) {
      const c = str.charCodeAt(i);
      const val = c < 128 ? INDEX[c] : -1;
      if (val < 0) throw new Error("base58: bad character " + JSON.stringify(str[i]));
      let carry = val;
      let j = 0;
      for (let k = out.length - 1; (carry !== 0 || j < length) && k >= 0; k--, j++) {
        carry += 58 * out[k];
        out[k] = carry & 0xff;
        carry >>>= 8;
      }
      length = j;
    }
    let it = out.length - length;
    while (it < out.length && out[it] === 0) it++;
    const total = zeros + (out.length - it);
    const decoded = new Uint8Array(total);
    for (let i = 0; i < zeros; i++) decoded[i] = 0;
    let p = zeros;
    while (it < out.length) decoded[p++] = out[it++];
    return decoded;
  }

  function encodeCheck(payload) {
    const bytes = payload instanceof Uint8Array ? payload : Uint8Array.from(payload);
    const check = sha256(sha256(bytes)).slice(0, 4);
    const full = new Uint8Array(bytes.length + 4);
    full.set(bytes, 0);
    full.set(check, bytes.length);
    return encodeBase58(full);
  }

  function decodeCheck(str) {
    const full = decodeBase58(str);
    if (full.length < 5) throw new Error("base58check: too short");
    const payload = full.slice(0, full.length - 4);
    const check = full.slice(full.length - 4);
    const want = sha256(sha256(payload)).slice(0, 4);
    for (let i = 0; i < 4; i++) if (check[i] !== want[i]) throw new Error("base58check: bad checksum");
    return payload;
  }

  return { encodeBase58, decodeBase58, encodeCheck, decodeCheck };
};