buildCsrForDid function

Future<String> buildCsrForDid(WalletStore wallet, String did, { String? countryCode, String? state, String? city, String? organization, String? organizationalUnit, String? emailAddress, })

Generate a x509 Certificate Signing Request for a key belonging to did.

Implementation

Future<String> buildCsrForDid(WalletStore wallet, String did,
    {String? countryCode,
    String? state,
    String? city,
    String? organization,
    String? organizationalUnit,
    String? emailAddress}) async {
  if (!did.startsWith('did:key:z6Mk')) {
    throw Exception('Only did:key with Ed25519 keys are supported now');
  }

  String? privateKey;
  privateKey = await wallet.getPrivateKeyForCredentialDid(did);
  privateKey ??= await wallet.getPrivateKeyForConnectionDid(did);
  if (privateKey == null) {
    throw Exception('Could not find private Key for DID $did');
  }

  var key = ed.PrivateKey(hexToBytes(privateKey).toList());
  var pub = ed.public(key);

  var csr = ASN1Sequence();
  var cri = ASN1Sequence();

  //Version
  cri.add(ASN1Integer(BigInt.zero));

  //subject
  var subject = ASN1Sequence();

  //countryCode in subject
  if (countryCode != null) {
    if (countryCode.length != 2) {
      throw Exception('Only two letter countryCodes are accepted');
    }
    var country = ASN1Sequence();
    country.add(ASN1ObjectIdentifier([2, 5, 4, 6], identifier: 'countryName'));
    country.add(ASN1PrintableString(countryCode));
    var countrySet = ASN1Set();
    countrySet.add(country);
    subject.add(countrySet);
  }

  if (state != null) {
    subject.add(_buildSubjectInfoPart('stateOrProvinceName', state));
  }
  if (city != null) {
    subject.add(_buildSubjectInfoPart('localityName', city));
  }
  if (organization != null) {
    subject.add(_buildSubjectInfoPart('organizationName', organization));
  }
  if (organizationalUnit != null) {
    subject.add(
        _buildSubjectInfoPart('organizationalUnitName', organizationalUnit));
  }

  subject.add(_buildSubjectInfoPart('commonName', did));

  //email
  if (emailAddress != null) {
    var country = ASN1Sequence();
    country.add(ASN1ObjectIdentifier([1, 2, 840, 113549, 1, 9, 1],
        identifier: 'countryName'));
    country.add(ASN1IA5String(emailAddress));
    var countrySet = ASN1Set();
    countrySet.add(country);
    subject.add(countrySet);
  }

  //subject public Key
  var publicKey = ASN1Sequence();
  var pubKeyId = ASN1Sequence();
  pubKeyId.add(ASN1ObjectIdentifier([1, 3, 101, 112]));
  publicKey.add(pubKeyId);
  publicKey.add(ASN1BitString(pub.bytes));
  var sigId = ASN1Sequence()..add(ASN1ObjectIdentifier([1, 3, 101, 112]));

  //build together Certificate Request Info
  cri.add(subject);
  cri.add(publicKey);

  //sign
  var sig = ed.sign(ed.PrivateKey(hexToBytes(privateKey).toList()),
      Uint8List.fromList(cri.encodedBytes));
  csr.add(cri);
  csr.add(sigId);
  csr.add(ASN1BitString(sig));

  //buildPem
  var buffer = StringBuffer();
  var bytes = csr.encodedBytes;
  buffer.writeln('-----BEGIN CERTIFICATE REQUEST-----');
  for (var i = 0; i < bytes.length; i += 48) {
    buffer.writeln(base64.encode(bytes.skip(i).take(48).toList()));
  }
  buffer.writeln('-----END CERTIFICATE REQUEST-----');
  return buffer.toString();
}