encryptJWE function

String encryptJWE(String data, Map<String, dynamic> key, { Map<String, dynamic>? epk, })

Encrypts the provided data using the specified key and optional epk. Returns the compact serialization of the encrypted JWE.

Implementation

String encryptJWE(
  String data,
  Map<String, dynamic> key, {
  Map<String, dynamic>? epk,
}) {
  var keyJwk = JsonWebKey.fromJson(key);

  var builder = JsonWebEncryptionBuilder();
  builder.stringContent = data;
  builder.addRecipient(keyJwk, algorithm: "dir");
  builder.encryptionAlgorithm = "A256GCM";

  if (epk != null) {
    var epkJwk = Jwk.fromJson(epk);
    builder.setProtectedHeader("epk", epkJwk.toJson());
  }

  var jwe = builder.build();
  var split = jwe.toCompactSerialization().split(".");

  if (epk != null) {
    String jsonString = utf8.decode(base64Url.decode(split[0]));
    var jsonObject = json.decode(jsonString);
    jsonObject["alg"] = "ECDH-ES";
    split[0] = base64Url.encode(utf8.encode(json.encode(jsonObject)));
    if (split[0].length % 4 != 0) {
      var paddingLength = 4 - (split[0].length % 4);
      split[0] += "=" * paddingLength;
    }
  }

  return split.join(".");
}