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Made fallback for missing recipients/header. #11

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15e5b43
fix(jwe): fallback parsing for missing recipients/header, support unp…
5eeman Oct 27, 2025
8f2a7d7
Downgraded crypto_keys_plus lower bound.
5eeman Oct 28, 2025
5998352
Format and add comments for updated constructor.
5eeman Oct 28, 2025
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6 changes: 6 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,3 +1,9 @@
## 0.4.8
- **FIX**: JWE JSON parsing now handles missing `recipients` / `header` by deriving a single recipient from the protected header and validates absent `encrypted_key` for non-`dir` algorithms.
- **FEAT**: Support unpadded Base64URL protected header (new parsing test).
- **TEST**: Added fallback, AAD, key wrap, and error path tests.
- **CHORE**: Refactored `JsonWebEncryption.fromJson` for clarity.

## 0.4.7
- **DEPS**: Remove dependency on `package:collection`
- **UPGRADE**: Updated to use crypto_keys_plus 0.5.0 which uses pointycastle 4.0.0.
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69 changes: 60 additions & 9 deletions lib/src/jwe.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -66,16 +66,67 @@ class JsonWebEncryption extends JoseObject {
JsonWebEncryption.fromJson(Map<String, dynamic> json)
: this._(
decodeBase64EncodedBytes(json['ciphertext']),
List.unmodifiable(json.containsKey('recipients')
? (json['recipients'] as List).map((v) => _JweRecipient._(
// Determine recipients according to RFC7516 general/flattened or
// fallback when neither recipients nor header are present.
List.unmodifiable(() {
if (json.containsKey('recipients')) {
// General JSON Serialization
return (json['recipients'] as List).map(
(v) => _JweRecipient._(
header: JsonObject.from(v['header']),
encryptedKey: decodeBase64EncodedBytes(v['encrypted_key'])))
: [
_JweRecipient._(
header: JsonObject.from(json['header']),
encryptedKey:
decodeBase64EncodedBytes(json['encrypted_key']))
]),
encryptedKey: decodeBase64EncodedBytes(v['encrypted_key']),
),
);
}
var encryptedKey = json.containsKey('encrypted_key')
? decodeBase64EncodedBytes(json['encrypted_key'])
: <int>[];

if (json.containsKey('header')) {
// Flattened JSON Serialization (header present)
var hdr = json['header'];
return [
_JweRecipient._(
header: hdr == null ? null : JsonObject.from(hdr),
encryptedKey: encryptedKey,
),
];
}
// (Do not treat presence of only 'encrypted_key' as flattened; fall back to protected header derivation)
// Fallback: No recipients array and no per-recipient header.
// Try to derive necessary information from protected header.
// This supports cases where all header parameters (alg, enc, kid, ...)
// are only present in the protected header.
var protectedHeader = json['protected'];
if (protectedHeader == null) {
throw ArgumentError('Missing protected header for JWE');
}
// We still build a single recipient to keep internal model consistent.
// encrypted_key may be legitimately absent for direct encryption (alg == 'dir').
JsonObject? derivedRecipientHeader;
var phDecoded = JsonObject.decode(protectedHeader);
var alg = phDecoded['alg'];
var kid = phDecoded['kid'];
if (alg != null) {
// Populate derived recipient header so downstream logic finds per-recipient alg
derivedRecipientHeader = JsonObject.from({
'alg': alg,
if (kid != null) 'kid': kid,
});
}

// Encrypted key must be present unless alg == 'dir'.
if (encryptedKey.isEmpty && alg != null && alg != 'dir') {
throw ArgumentError('Missing encrypted_key for algorithm "$alg"');
}

return [
_JweRecipient._(
header: derivedRecipientHeader,
encryptedKey: encryptedKey,
),
];
}()),
protectedHeader: JsonObject.decode(json['protected']),
unprotectedHeader: json['unprotected'] == null
? null
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4 changes: 2 additions & 2 deletions pubspec.yaml
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
name: jose_plus
description: Javascript Object Signing and Encryption (JOSE) library supporting JWE, JWS, JWK and JWT
version: 0.4.7
version: 0.4.8
homepage: https://github.com/Bdaya-Dev/jose
funding:
- https://github.com/sponsors/rbellens
Expand All @@ -9,7 +9,7 @@ environment:
sdk: ^3.0.0

dependencies:
crypto_keys_plus: ">=0.5.0 <1.0.0"
crypto_keys_plus: ">=0.4.0 <1.0.0"
meta: ^1.1.6
typed_data: ^1.0.0
x509_plus: ">=0.3.3 <1.0.0"
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115 changes: 115 additions & 0 deletions test/jwe_test.dart
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
import 'dart:convert';

import 'package:jose_plus/jose.dart';
import 'package:jose_plus/src/util.dart';
import 'package:test/test.dart';

void main() {
Expand Down Expand Up @@ -285,6 +286,120 @@ void main() {
jwe.getPayloadFor(jwk, jwe.commonHeader, jwe.recipients.first)!),
'{"aud": "somekey", "sub": 12, "iss": "auth.example.com", "exp": 1617349353}');
});

group('Fallback JWE JSON parsing (no recipients/header)', () {
test('Direct encryption without encrypted_key succeeds', () async {
var payload = 'Secret message';
var builder = JsonWebEncryptionBuilder()..stringContent = payload;
builder.encryptionAlgorithm = 'A256GCM';
// Generate a symmetric key for direct encryption
var key = JsonWebKey.generate(builder.encryptionAlgorithm);
builder.addRecipient(key, algorithm: 'dir');
var jwe = builder.build();
// Build JSON representation without recipients/header and intentionally omit encrypted_key
var compact = jwe.toCompactSerialization().split('.');
// compact parts: [protected, encrypted_key (empty for dir), iv, ciphertext, tag]
var fallbackJson = {
'protected': compact[0],
// intentionally no 'encrypted_key'
'iv': compact[2],
'ciphertext': compact[3],
'tag': compact[4]
};
var parsed = JsonWebEncryption.fromJson(fallbackJson);
var keyStore = JsonWebKeyStore()..addKey(key);
expect((await parsed.getPayload(keyStore)).stringContent, payload);
});

test('Missing encrypted_key for non-direct algorithm throws', () async {
var payload = 'Another secret';
var builder = JsonWebEncryptionBuilder()..stringContent = payload;
builder.encryptionAlgorithm = 'A128CBC-HS256';
// Use an octet key suitable for key wrapping (A128KW)
var key =
JsonWebKey.fromJson({'kty': 'oct', 'k': 'GawgguFyGrWKav7AX4VKUg'});
builder.addRecipient(key, algorithm: 'A128KW');
var jwe = builder.build();
var compact = jwe.toCompactSerialization().split('.');
// Remove encrypted_key field
var fallbackJson = {
'protected': compact[0],
// encrypted_key omitted but algorithm in protected header is not 'dir'
'iv': compact[2],
'ciphertext': compact[3],
'tag': compact[4]
};
expect(
() => JsonWebEncryption.fromJson(fallbackJson), throwsArgumentError);
});

test('Parse JWE protected header (Base64URL unpadded)', () {
final jweJson = {
'ciphertext':
'F9vgLFXCxXd46RVux-YNAT0aSxAevRvz0Po1vLrbc45vTC3r_S8fv2S24I9IVOjRvE1CJm73-cyf04CvtngCiyLwgzhnr2hFiIzVOQ4bM077_KqHkn0rWHD5xGekxNHcGpVMkcXfhwnRGNMTCfcnJV5YbolDNYXwYJw4Wcjk2suLCPB-NFK0yuakmszOzC82PIlKBJ4VQ0Gjh_R5DsQoz00IcpvQogzsYWxgbV87TsGXrjqbV8x97ng_8B0V0Yd9EURg3SWJqsuWFPFig9k2voNwurztmKoRiNbYEdIV5Zn-AP96G7p4i76rY0h_v-NdBsTz38z17Qu_1W8-RNsdcH0rGUblQPQV6VWVQjrS3D6AfSoz-uoYga2X3BISU1GTmsqtHnOauq03aT2pN33PqxQ0nxQgJ1bvU1E4BuHugN6Mt9kVwv9ssNeYk3QE6gax4LE24f1SGH3-PfKQ0hwGfeql6yRdVA',
'encrypted_key':
'eId1wPPb7TEH9PazhcUsYEk5_nPOfVmqxwui7W7k5bqbIvIsJKX7vIh3xrcYF51fheHvOdZfqewWoJY3PTtPwBg1pJ-IE6V8UPKFpyJ6p8ETjKpypE5VijXrYeqTfFAXxpU3dhk5xVnm7eF8YfymmqzHA2_ErFzqbHu6e5JK6xGFkSc_bMINBBs1612ow1HHBr1LnnGUGM5hVX0bydisnJG9kkxLX7PH_0Np1vzkRspVlsi16zK4uA09GXraxIVo5GQNPoEdoAqC7AK71DzThOBMZMbN7incVJxegBnO8G0oqkG9IvCHHglTP6wtOVF_qzNNZ36-q5uxDatw4-oc6Q',
'iv': '4fX9lmzwwR1d4Jbw',
'protected':
'eyJhbGciOiJSU0EtT0FFUC0yNTYiLCJlbmMiOiJBMjU2R0NNIiwia2lkIjoiZGlkOmlkZW4zOmJpbGxpb25zOnRlc3Q6MlZ4bm9pTnFkTVB5SE10VXdBRXpobldxWEdrRWVKcEFwNG50VGtMOFhUI2tleTEiLCJ0eXAiOiJhcHBsaWNhdGlvbi9pZGVuM2NvbW0tZW5jcnlwdGVkLWpzb24ifQ',
'tag': 'of7WWH7gbhEiADgowsXiOA',
};
// Parsing should succeed and derive header values from protected header (unpadded base64url)
final jwe = JsonWebEncryption.fromJson(jweJson);
final header = jwe.commonHeader;
expect(header.algorithm, 'RSA-OAEP-256');
expect(header.encryptionAlgorithm, 'A256GCM');
expect(header.type, 'application/iden3comm-encrypted-json');
expect(header.keyId, isNotNull);
// Ensure keyId has expected suffix fragment
expect(header.keyId!.endsWith('#key1'), isTrue);
// Ensure no recipients array created (flattened/fallback single recipient)
expect(jwe.recipients.length, 1);
});

test('Key wrapping (non-dir) fallback with encrypted_key present',
() async {
var payload = 'Key wrap fallback';
var builder = JsonWebEncryptionBuilder()..stringContent = payload;
builder.encryptionAlgorithm = 'A128CBC-HS256';
var key =
JsonWebKey.fromJson({'kty': 'oct', 'k': 'GawgguFyGrWKav7AX4VKUg'});
builder.addRecipient(key, algorithm: 'A128KW');
var jwe = builder.build();
var parts = jwe.toCompactSerialization().split('.');
var fallbackJson = {
'protected': parts[0],
'encrypted_key': parts[1],
'iv': parts[2],
'ciphertext': parts[3],
'tag': parts[4]
};
var parsed = JsonWebEncryption.fromJson(fallbackJson);
var store = JsonWebKeyStore()..addKey(key);
expect((await parsed.getPayload(store)).stringContent, payload);
expect(parsed.commonHeader.algorithm, 'A128KW');
expect(parsed.commonHeader.encryptionAlgorithm, 'A128CBC-HS256');
});

test('Error when protected header missing', () {
var json = {
'iv': 'AA',
'ciphertext': 'AA',
'tag': 'AA'
}; // intentionally minimal
expect(() => JsonWebEncryption.fromJson(json), throwsArgumentError);
});

test('Error for invalid protected header base64/json', () {
var json = {
'protected': '***', // invalid base64 / json
'iv': 'AA',
'ciphertext': 'AA',
'tag': 'AA'
};
expect(() => JsonWebEncryption.fromJson(json), throwsA(isA<Exception>()));
});
});
}

void _doTests(dynamic payload, dynamic key, dynamic encoded) {
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