hashcash 1.0.0

  • README.md
  • Example
  • Installing
  • Versions
  • 28


Hashcash is a proof-of-work algorithm, which has been used as a denial-of-service counter measure technique in a number of systems.

A hashcash stamp constitutes a proof-of-work which takes a parameterizable amount of work to compute for the sender. The recipient (and indeed anyone as it is publicly auditable) can verify received hashcash stamps efficiently. Hashcash was invented by Adam Back in 1997

How to use it

Call HashCash.mint to generate a stamp and use HashCash.check to verify if this stamp is correct



update to crypto 1.1.1 for significant improvement


  • Initial version, created by Stagehand


// Copyright (c) 2015, Kevin Segaud. All rights reserved. Use of this source code
// is governed by a BSD-style license that can be found in the LICENSE file.

import "package:hashcash/hashcash.dart";

main() {
  String stamp = HashCash.mint("segaud.kevin@gmail.com");
  print(HashCash.check(stamp, resource: "segaud.kevin@gmail.com"));

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  hashcash: ^1.0.0

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter packages get

Alternatively, your editor might support pub get or flutter packages get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:hashcash/hashcash.dart';
Version Uploaded Documentation Archive
1.0.0 May 11, 2016 Go to the documentation of hashcash 1.0.0 Download hashcash 1.0.0 archive
0.0.1 May 11, 2016 Go to the documentation of hashcash 0.0.1 Download hashcash 0.0.1 archive
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Learn more about scoring.

We analyzed this package on Jul 20, 2018, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.0.0-dev.69.0
  • pana: 0.11.7


Detected platforms: Flutter, web, other

No platform restriction found in primary library package:hashcash/hashcash.dart.

Issues and suggestions

Support Dart 2 in pubspec.yaml.

The SDK constraint in pubspec.yaml doesn't allow the Dart 2.0.0 release. For information about upgrading it to be Dart 2 compatible, please see https://www.dartlang.org/dart-2#migration.

Package is too old.

The package was released more than two years ago.

Fix lib/src/hashcash.dart.

Analysis of lib/src/hashcash.dart reported 6 hints, including:

line 90 col 40: 'onError' is deprecated and shouldn't be used.

line 94 col 54: 'onError' is deprecated and shouldn't be used.

line 95 col 56: 'onError' is deprecated and shouldn't be used.

line 96 col 55: 'onError' is deprecated and shouldn't be used.

line 103 col 53: 'onError' is deprecated and shouldn't be used.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.0.0 <2.0.0
crypto >=1.1.1 <2.0.0 1.1.1 2.0.6
Transitive dependencies
charcode 1.1.2
collection 1.14.11
convert 1.1.1 2.0.2
typed_data 1.1.6
Dev dependencies
benchmark_harness any
test any