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Dart

Sign a JWS with an HMAC Key

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.SetMacKey, which sets the symmetric MAC key for a signature. The key bytes are supplied in a named encoding such as hex or base64.

Background. HMAC-based JWS (for example HS256) authenticates the payload with a shared symmetric key that both signer and verifier possess.

Chilkat Dart Downloads

Dart
import 'package:chilkat/chilkat.dart';

void main() {
  final jws = CkJws();

  // Protected header specifying HMAC-SHA256.
  final header = CkJsonObject();
  header.updateString('alg', 'HS256');
  try {
    jws.setProtectedHeader(0, header);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final bIncludeBom = false;
  try {
    jws.setPayload('This is the content to sign.', 'utf-8', bIncludeBom);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Set the symmetric MAC key for signature 0.  The key bytes are provided in the named encoding (here
  // base64).  In production, obtain the key from a secure source rather than hard-coding it.
  final base64Key = 'YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU=';
  try {
    jws.setMacKey(0, base64Key, 'base64');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final String jwsCompact;
  try {
    jwsCompact = jws.createJws();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print(jwsCompact);
}