refactor: PR #26

ethicnology · Apr 20, 2023 · e6add66 · e6add66
1 parent cc429de
commit e6add66
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Showing 3 changed files with 76 additions and 126 deletions.
diff --git a/lib/src/event.dart b/lib/src/event.dart
@@ -128,27 +128,26 @@ class Event {
     );
   }
 
-  /// Instantiate Event object from the minimum available data
+  /// Instantiate Event object from the minimum needed data
   ///
   /// ```dart
   ///Event event = Event.from(
   ///  kind: 1,
-  ///  tags: [],
   ///  content: "",
   ///  privkey:
   ///      "5ee1c8000ab28edd64d74a7d951ac2dd559814887b1b9e1ac7c5f89e96125c12",
   ///);
   ///```
   factory Event.from({
-    int createdAt = 0,
+    int? createdAt,
     required int kind,
-    required List<List<String>> tags,
+    List<List<String>> tags = const [],
     required String content,
     required String privkey,
     String? subscriptionId,
     bool verify = false,
   }) {
-    if (createdAt == 0) createdAt = currentUnixTimestampSeconds();
+    createdAt ??= currentUnixTimestampSeconds();
     final pubkey = bip340.getPublicKey(privkey).toLowerCase();
 
     final id = _processEventId(
@@ -271,20 +270,6 @@ class Event {
     );
   }
 
-  factory Event.quick(
-    String content,
-    String privkey,
-  ) {
-    Event event = Event.partial();
-    event.kind = 1;
-    event.content = content;
-    event.createdAt = currentUnixTimestampSeconds();
-    event.pubkey = bip340.getPublicKey(privkey).toLowerCase();
-    event.id = event.getEventId();
-    event.sig = event.getSignature(privkey);
-    return event;
-  }
-
   /// To obtain the event.id, we sha256 the serialized event.
   /// The serialization is done over the UTF-8 JSON-serialized string (with no white space or line breaks) of the following structure:
   ///

diff --git a/lib/src/nips/nip_004/crypto.dart b/lib/src/nips/nip_004/crypto.dart
@@ -1,105 +1,66 @@
 import 'dart:convert';
 import 'dart:math';
 import 'dart:typed_data';
+import 'package:nostr/src/crypto/kepler.dart';
 import 'package:pointycastle/export.dart';
 
-import '../../crypto/kepler.dart';
-
 class Nip4 {
-  static Map<String, List<List<int>>> gMapByteSecret = {};
-  // pointy castle source https://github.com/PointyCastle/pointycastle/blob/master/tutorials/aes-cbc.md
-  // https://github.com/bcgit/pc-dart/blob/master/tutorials/aes-cbc.md
-  // 3 https://github.com/Dhuliang/flutter-bsv/blob/42a2d92ec6bb9ee3231878ffe684e1b7940c7d49/lib/src/aescbc.dart
-
-  // Encrypt data using self private key in nostr format ( with trailing ?iv=)
-  static String cipher(
-    String privkey,
-    String pubkey,
-    String plaintext,
-  ) {
-    Uint8List uintInputText = Utf8Encoder().convert(plaintext);
-    final secretIV = Kepler.byteSecret(privkey, pubkey);
-    final key = Uint8List.fromList(
-      secretIV[0],
+  static Uint8List generateNonce() {
+    final random = Random.secure();
+    return Uint8List.fromList(
+      List<int>.generate(16, (i) => random.nextInt(256)),
     );
-
-    // generate iv  https://stackoverflow.com/questions/63630661/aes-engine-not-initialised-with-pointycastle-securerandom
-    FortunaRandom fr = FortunaRandom();
-    final sGen = Random.secure();
-    fr.seed(KeyParameter(
-        Uint8List.fromList(List.generate(32, (_) => sGen.nextInt(255)))));
-    final iv = fr.nextBytes(16);
-
-    CipherParameters params = PaddedBlockCipherParameters(
-        ParametersWithIV(KeyParameter(key), iv), null);
-
-    PaddedBlockCipherImpl cipherImpl =
-        PaddedBlockCipherImpl(PKCS7Padding(), CBCBlockCipher(AESEngine()));
-
-    cipherImpl.init(
-        true, // means to encrypt
-        params as PaddedBlockCipherParameters<CipherParameters?,
-            CipherParameters?>);
-
-    // allocate space
-    final Uint8List outputEncodedText = Uint8List(uintInputText.length + 16);
-
-    var offset = 0;
-    while (offset < uintInputText.length - 16) {
-      offset += cipherImpl.processBlock(
-          uintInputText, offset, outputEncodedText, offset);
-    }
-
-    //add padding
-    offset +=
-        cipherImpl.doFinal(uintInputText, offset, outputEncodedText, offset);
-    final Uint8List finalEncodedText = outputEncodedText.sublist(0, offset);
-
-    String stringIv = base64.encode(iv);
-    String outputPlainText = base64.encode(finalEncodedText);
-    outputPlainText = "$outputPlainText?iv=$stringIv";
-    return outputPlainText;
   }
 
-  static String decipher(
+  static String cipher(
     String privkey,
     String pubkey,
-    String ciphertext, [
-    String nonce = "",
-  ]) {
-    Uint8List cipherText = base64.decode(ciphertext);
-    List<List<int>> byteSecret = gMapByteSecret[pubkey] ?? [];
-    if (byteSecret.isEmpty) {
-      byteSecret = Kepler.byteSecret(privkey, pubkey);
-      gMapByteSecret[pubkey] = byteSecret;
+    String payload,
+    bool cipher, {
+    String? nonce,
+  }) {
+    // if cipher=false –> decipher –> nonce needed
+    if (!cipher && nonce == null) throw Exception("missing nonce");
+
+    // init variables
+    Uint8List input, output, iv;
+    if (!cipher && nonce != null) {
+      input = base64.decode(payload);
+      output = Uint8List(input.length);
+      iv = base64.decode(nonce);
+    } else {
+      input = Utf8Encoder().convert(payload);
+      output = Uint8List(input.length + 16);
+      iv = generateNonce();
     }
-    final secretIV = byteSecret;
-    final key = Uint8List.fromList(secretIV[0]);
-    final iv = nonce.length > 6
-        ? base64.decode(nonce)
-        : Uint8List.fromList(secretIV[1]);
 
-    CipherParameters params = PaddedBlockCipherParameters(
-        ParametersWithIV(KeyParameter(key), iv), null);
-
-    PaddedBlockCipherImpl cipherImpl =
-        PaddedBlockCipherImpl(PKCS7Padding(), CBCBlockCipher(AESEngine()));
-
-    cipherImpl.init(
-        false,
-        params as PaddedBlockCipherParameters<CipherParameters?,
-            CipherParameters?>);
-    final Uint8List finalPlainText =
-        Uint8List(cipherText.length); // allocate space
+    // params
+    List<List<int>> keplerSecret = Kepler.byteSecret(privkey, pubkey);
+    var key = Uint8List.fromList(keplerSecret[0]);
+    var params = PaddedBlockCipherParameters(
+      ParametersWithIV(KeyParameter(key), iv),
+      null,
+    );
+    var algo = PaddedBlockCipherImpl(
+      PKCS7Padding(),
+      CBCBlockCipher(AESEngine()),
+    );
 
+    // processing
+    algo.init(cipher, params);
     var offset = 0;
-    while (offset < cipherText.length - 16) {
-      offset +=
-          cipherImpl.processBlock(cipherText, offset, finalPlainText, offset);
+    while (offset < input.length - 16) {
+      offset += algo.processBlock(input, offset, output, offset);
+    }
+    offset += algo.doFinal(input, offset, output, offset);
+    Uint8List result = output.sublist(0, offset);
+
+    if (cipher) {
+      String stringIv = base64.encode(iv);
+      String plaintext = base64.encode(result);
+      return "$plaintext?iv=$stringIv";
+    } else {
+      return Utf8Decoder().convert(result);
     }
-    //remove padding
-    offset += cipherImpl.doFinal(cipherText, offset, finalPlainText, offset);
-    Uint8List result = finalPlainText.sublist(0, offset);
-    return Utf8Decoder().convert(result);
   }
 }
diff --git a/lib/src/nips/nip_004/event.dart b/lib/src/nips/nip_004/event.dart
@@ -4,8 +4,6 @@ import 'package:nostr/src/nips/nip_004/crypto.dart';
 import 'package:nostr/src/utils.dart';
 
 class EncryptedDirectMessage extends Event {
-  static Map<String, List<List<int>>> gMapByteSecret = {};
-
   EncryptedDirectMessage(Event event)
       : super(
           event.id,
@@ -31,36 +29,42 @@ class EncryptedDirectMessage extends Event {
     event.tags = [
       ['p', receiverPubkey]
     ];
-    event.content = Nip4.cipher(senderPrivkey, '02$receiverPubkey', message);
+    event.content = Nip4.cipher(
+      senderPrivkey,
+      '02$receiverPubkey',
+      message,
+      true,
+    );
     event.id = event.getEventId();
     event.sig = event.getSignature(senderPrivkey);
     return EncryptedDirectMessage(event);
   }
 
   String? get receiverPubkey => findPubkey();
 
+  String get nonce {
+    List<String> split = content.split("?iv=");
+    if (split.length != 2) throw Exception("invalid nip4 content");
+    return split[1];
+  }
+
   String getCiphertext(String senderPrivkey, String receiverPubkey) {
-    String ciphertext =
-        Nip4.cipher(senderPrivkey, '02$receiverPubkey', content);
-    return ciphertext;
+    return Nip4.cipher(senderPrivkey, '02$receiverPubkey', content, true);
   }
 
-  String getPlaintext(String receiverPrivkey, [String senderPubkey=""]) {
-    if (senderPubkey.length == 0) {
-      senderPubkey = pubkey;
-    }
+  String getPlaintext(String receiverPrivkey) {
+    String ciphertext = content.split("?iv=")[0];
     String plaintext = "";
-    int ivIndex = content.indexOf("?iv=");
-    if( ivIndex <= 0) {
-      print("Invalid content for dm, could not get ivIndex: $content");
-      return plaintext;
-    }
-    String iv = content.substring(ivIndex + "?iv=".length, content.length);
-    String ciphertext = content.substring(0, ivIndex);
     try {
-      plaintext = Nip4.decipher(receiverPrivkey, "02$senderPubkey", ciphertext, iv);
-    } catch(e) {
-      print("Fail to decrypt: ${e}");
+      plaintext = Nip4.cipher(
+        receiverPrivkey,
+        "02$pubkey",
+        ciphertext,
+        false,
+        nonce: nonce,
+      );
+    } catch (e) {
+      throw Exception("Fail to decipher: $e");
     }
     return plaintext;
   }