first commit

.gitignore

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+# Files and directories created by pub
+.dart_tool/
+.packages
+pubspec.lock
+
+# Temporary Files
+.tmp/
+
+# Android studio and IntelliJ
+.idea
+
+# Misc files
+.DS_Store

LICENSE

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+MIT License
+
+Copyright (c) 2024 Dominik Šimoník
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+### Cashu
+
+[![License: MIT][license_badge]][license_link]
+
+⚠️ **Warning:** This project is work in progress
+
+Library for [Cashu](https://github.com/cashubtc) wallets written in Dart.
+
+## Supported NUTs
+
+Implemented [NUTs](https://github.com/cashubtc/nuts/):
+
+- [] [NUT-00](https://github.com/cashubtc/nuts/blob/main/00.md)
+- [] [NUT-01](https://github.com/cashubtc/nuts/blob/main/01.md)
+- [] [NUT-02](https://github.com/cashubtc/nuts/blob/main/02.md)
+- [] [NUT-03](https://github.com/cashubtc/nuts/blob/main/03.md)
+- [] [NUT-04](https://github.com/cashubtc/nuts/blob/main/04.md)
+- [] [NUT-05](https://github.com/cashubtc/nuts/blob/main/05.md)
+- [] [NUT-06](https://github.com/cashubtc/nuts/blob/main/06.md)
+- [] [NUT-07](https://github.com/cashubtc/nuts/blob/main/07.md)
+- [] [NUT-08](https://github.com/cashubtc/nuts/blob/main/08.md)
+- [] [NUT-09](https://github.com/cashubtc/nuts/blob/main/09.md)
+- [] [NUT-10](https://github.com/cashubtc/nuts/blob/main/10.md)
+- [] [NUT-11](https://github.com/cashubtc/nuts/blob/main/11.md)
+- [] [NUT-12](https://github.com/cashubtc/nuts/blob/main/12.md)
+
+## Contribute
+
+Contributions are very welcome.
+
+If you want to contribute, please open an Issue or a PR.
+
+[license_badge]: https://img.shields.io/badge/license-MIT-blue.svg
+[license_link]: https://opensource.org/licenses/MIT
+

analysis_options.yaml

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+include: package:flutter_lints/flutter.yaml

lib/cashu.dart

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+library;
+
+export 'src/cashu.dart';

lib/src/base64.dart

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+import 'dart:convert';
+
+String base64UrlToBase64(String base64Url) {
+  return base64Url.replaceAll('_', '/').replaceAll('-', '+');
+}
+
+String base64ToBase64Url(String base64) {
+  return base64.replaceAll('+', '-').replaceAll('/', '_');
+}
+
+Map<String, dynamic> base64toJson(String base64) {
+  // Directly decode the Base64 string, which may include padding characters
+  return jsonDecode(utf8.decode(base64Decode(base64))) as Map<String, dynamic>;
+}
+
+String jsonToBase64(Map<String, dynamic> json) {
+  // Encode the JSON to a UTF-8 byte array, then to a standard Base64 string
+  return base64Encode(utf8.encode(jsonEncode(json)));
+}

lib/src/cashu.dart

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+import 'package:cashu/src/base64.dart';
+import 'package:cashu/src/constants.dart';
+import 'package:cashu/src/model/cashu_token.dart';
+
+class Cashu {
+  static CashuToken getDecodedToken(String serialized) {
+    final prefix = serialized.startsWith(kTokenPrefix);
+
+    if (!prefix) {
+      throw Exception('Invalid token prefix');
+    }
+
+    final version =
+        serialized.substring(kTokenPrefix.length, kTokenPrefix.length + 1);
+
+    if (!kSupportedVersions.contains(version)) {
+      throw Exception('Unsupported token version');
+    }
+
+    final base64Dirty = serialized.substring(kTokenPrefix.length + 1);
+
+    final cleanedBase64url = base64UrlToBase64(base64Dirty);
+
+    final json = base64toJson(cleanedBase64url);
+
+    return CashuToken.fromJson(json);
+  }
+
+  static CashuToken getDecodedTokenUri(Uri uri) {
+    if (kCashuUriSchemes.contains(uri.scheme)) {
+      throw Exception('Invalid scheme');
+    }
+
+    final token = uri.host;
+
+    return getDecodedToken(token);
+  }
+}

lib/src/constants.dart

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+const kTokenPrefix = 'cashu';
+const kTokenVersion3 = 'A';
+const kSupportedVersions = [kTokenVersion3];
+const kCashuUriSchemes = ['cashu:', 'cashu://', 'web+cashu://'];

lib/src/helpers.dart

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+import 'dart:core';
+import 'dart:typed_data';
+
+import 'package:convert/convert.dart';
+
+Uint8List hexDecode(String input) {
+  final list = hex.decode(input);
+  return Uint8List.fromList(list);
+}
+
+String hexEncode(Uint8List input) {
+  return hex.encode(input);
+}

lib/src/model/blind_signature.dart

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+class BlindSignature {
+  BlindSignature({
+    required this.amount,
+    required this.id,
+    required this.C_,
+  });
+
+  final int amount;
+  final String id;
+  final String C_;
+}

lib/src/model/blinded_message.dart

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+class BlindedMessage {
+  BlindedMessage({
+    required this.amount,
+    required this.id,
+    required this.B_,
+  });
+
+  final int amount;
+  final String id;
+  final String B_;
+}
+
+typedef BlindedMessages = List<BlindedMessage>;

lib/src/model/cashu_token.dart

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+import 'package:cashu/src/base64.dart';
+import 'package:cashu/src/constants.dart';
+import 'package:cashu/src/model/token.dart';
+
+class CashuToken {
+  CashuToken({
+    required this.token,
+    this.unit,
+    this.memo,
+  });
+
+  final String? unit;
+  final String? memo;
+  final List<Token> token;
+
+  factory CashuToken.fromJson(Map<String, dynamic> json) {
+    final token = json['token'] as List<dynamic>;
+
+    final tokenList =
+        token.map((e) => Token.fromJson(e as Map<String, dynamic>)).toList();
+
+    final unit = json['unit'] as String?;
+    final memo = json['memo'] as String?;
+
+    return CashuToken(
+      token: tokenList,
+      unit: unit,
+      memo: memo,
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'token': token.map((e) => e.toJson()).toList(),
+        if (unit != null) 'unit': unit,
+        if (memo != null) 'memo': memo,
+      };
+
+  String serialize() {
+    final json = toJson();
+
+    final base64url = jsonToBase64(json);
+
+    final token = '$kTokenPrefix$kTokenVersion3$base64url';
+    return token;
+  }
+}

lib/src/model/error.dart

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+class ProtocolError {
+  ProtocolError({
+    required this.detail,
+    required this.code,
+  });
+
+  final String detail;
+  final int code;
+}

lib/src/model/proof.dart

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+class Proof {
+  Proof({
+    required this.amount,
+    required this.id,
+    required this.secret,
+    required this.C,
+  });
+
+  final int amount;
+  final String id;
+  final String secret;
+  final String C;
+
+  factory Proof.fromJson(Map<String, dynamic> json) {
+    return Proof(
+      amount: json['amount'] as int,
+      id: json['id'] as String,
+      secret: json['secret'] as String,
+      C: json['C'] as String,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'amount': amount,
+      'secret': secret,
+      'C': C,
+    };
+  }
+}

lib/src/model/token.dart

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+import 'package:cashu/src/model/proof.dart';
+
+class Token {
+  Token({
+    required this.mint,
+    required this.proofs,
+  });
+
+  final String mint;
+  final List<Proof> proofs;
+
+  factory Token.fromJson(Map<String, dynamic> json) {
+    final proofs = json['proofs'] as List<dynamic>;
+
+    final proofList =
+        proofs.map((e) => Proof.fromJson(e as Map<String, dynamic>)).toList();
+
+    return Token(
+      mint: json['mint'] as String,
+      proofs: proofList,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'mint': mint,
+      'proofs': proofs.map((e) => e.toJson()).toList(),
+    };
+  }
+}

lib/src/utils.dart

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+import 'dart:typed_data';
+import 'package:pointycastle/export.dart';
+
+final secp256k1 = ECDomainParameters('secp256k1');
+
+ECPoint hashToCurve(Uint8List secret) {
+  ECPoint? point;
+  while (point == null) {
+    final hash = sha256(secret);
+    final hashHex = bytesToHex(hash);
+    final pointX = '02$hashHex';
+    try {
+      point = pointFromHex(pointX);
+    } catch (e) {
+      print(e);
+    }
+  }
+  return point;
+}
+
+ECPoint pointFromHex(String hex) {
+  return secp256k1.curve.decodePoint(hexToBytes(hex))!;
+}
+
+Uint8List sha256(Uint8List data) {
+  final digest = SHA256Digest();
+  return Uint8List.fromList(digest.process(data));
+}
+
+String bytesToHex(Uint8List bytes) {
+  return bytes.map((byte) => byte.toRadixString(16).padLeft(2, '0')).join();
+}
+
+Uint8List hexToBytes(String hex) {
+  final result = Uint8List(hex.length ~/ 2);
+  for (var i = 0; i < hex.length; i += 2) {
+    final number = int.parse(hex.substring(i, i + 2), radix: 16);
+    result[i ~/ 2] = number;
+  }
+  return result;
+}

pubspec.yaml

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+name: cashu
+description: Library for cashu wallets
+version: 0.1.0
+repository: https://github.com/ryzizub/cashu
+
+environment:
+  sdk: ^3.2.0
+
+dependencies:
+  convert: ^3.1.1
+  crypto: ^3.0.3
+  pointycastle: ^3.7.3
+  typed_data: ^1.3.2
+
+dev_dependencies:
+  flutter_lints: ^3.0.1
+  test: ^1.14.4