Signer for Lark webhooks

lark_signer.dart

import 'dart:convert';

import 'package:crypto/crypto.dart';

Map<String, String> sign({
  required String key,
  DateTime? dateTime,
}) {
  dateTime ??= DateTime.now();
  final int timestamp = dateTime.millisecondsSinceEpoch ~/ 1000;
  final Hmac signKey = Hmac(sha256, utf8.encode('$timestamp\n$key'));
  final Digest digest = signKey.convert(<int>[]);
  final String sign = base64.encode(digest.bytes);
  return <String, String>{'timestamp': '$timestamp', 'sign': sign};
}