anchor.diff:      throw UnimplementedError('TODO: implement AES-KW');
     }
   
  +  static Future<AesKwSecretKey> importJsonWebKey({
  +    @required List<int> jwk,
  +    @required bool extractable,
  +    @required List<KeyUsage> usages,
  +  }) {
  +    ArgumentError.checkNotNull(jwk, 'jwk');
  +    ArgumentError.checkNotNull(extractable, 'extractable');
  +    checkAllowedUsages('AES-KW', usages, [
  +      // KeyUsage.wrapKey,
  +      // KeyUsage.unwrapKey,
  +    ]);
  +    usages = normalizeUsages(usages);
  +
  +    throw UnimplementedError('TODO: implement AES-KW');
  +  }
  +
     // TODO: add wrapKey support
     // TODO: add unwrapKey support
   
     Future<List<int>> exportRawKey();
  -}
  +
  +  Future<Map<String, Object>> exportJsonWebKey();
  +}*/
   
   abstract class EcdhPrivateKey implements CryptoKey {
     EcdhPrivateKey._(); // keep the constructor private.
  
positive.code:   });
  
    Future<List<int>> exportSpkiKey();
  }
  
  enum EllipticCurve {
  
negative.code:   // TODO: add unwrapKey support
  
    Future<List<int>> exportPkcs8Key();
  
    Future<Map<String, Object>> exportJsonWebKey();
  }
  
  abstract class RsaOaepPublicKey implements CryptoKey {
  