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A Java implementation of the Bitcoin protocol, for phones and apps
A Java implementation of the Bitcoin protocol, for phones and apps


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After many months of work, the bitcoinj team has released version 0.13!

The highlights of this release include

* Dramatically improved performance, especially for big wallets that contain many large sendmany transactions e.g. from mining pool payouts
* Much faster Tor performance
* A new MySQL based block store
* Ability for the wallet to use a UTXO database instead of its own internal data structures. A good place to get a UTXO database is by building one using the MySQL/Postgres/H2 block stores that come with bitcoinj. This is a major step forward for allowing bitcoinj to be easily used for making web wallets and other hosted wallet services.

Many other API cleanups, tweaks and new features have been added too. The Lighthouse crowdfunding wallet was developed alongside 0.13 in parallel and many improvements made as part of developing this smart contracts app were made available for general use in this release. So it should be easier than ever to build advanced smart contract apps now.

Let us know how you find it!

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The tutorial talk given at DevCore 2015, "How to build a timestamping app in under 30 minutes" is now available on YouTube and GitHub:

It covers how to use the bitcoinj wallet-template app to build a cross platform, Tor supporting, decentralised, peer to peer, 3D accelerated, block chain based document timestamping app ...... from scratch. Is that enough buzzwords for you? Then check it out!

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Happy new year to everyone who uses or develops bitcoinj!

I wrote a retrospective on 2014 and some wishes for the new year. We did pretty well with last years new year wishes ... let's hope our good luck continues! :)

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We have released version 0.12 of bitcoinj! This release represents 8 months of work and is packed with great new features that should start showing up in your apps soon.

The most interesting new features are HD wallets, support for multisig wallets, the bundled Tor client, a better bundled GUI wallet app (this is used as the basis for a few different end user apps now, like Lighthouse) and new tutorials showing how to use the library from Javascript / how to make a custom GUI wallet app.

bitcoinj has been on a tear lately. It's gathered a big community of users and contributors. Thanks to everyone who helps make it happen!

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Some new features in recent bitcoinj master:

- Kosta Korenkov (@troggy on github) has implemented the first part of married wallets support. You can now marry a wallet to a third party HD tree e.g. on a remote server and that wallet will start vending multi-sig P2SH addresses. Currently if you do this, you'll have to sign transactions yourself (this is quite easy). Hopefully in future bitcoinj will have a plugin system so different risk analysis providers can be presented with a uniform interface.

- WalletTemplate now shows how to implement online restore from seed words, with real-time validation as you type.

- Old random wallets are upgraded to HD wallets on the fly, using the oldest private key in the old wallet as the seed. This means the upgrade to HD should be seamless for our existing user base.

- Andreas implemented decryption of BIP38 encrypted private keys, as part of work he's doing on supporting paper wallets in Bitcoin Wallet for Android.

+Andreas Schildbach has been on fire lately: his commits are just rolling right in to bitcoinj master. Andreas has been improving protocol compliance, cleaning up the code and fixing long-standing warts and gaps in our API. His work not only benefits his own Bitcoin Wallet for Android app but everyone else's apps too. You can tip him at 18CK5k1gajRKKSC7yVSTXT9LUzbheh1XY4

In other news, we merged HD wallets support to master as well. Although it's a good milestone, the work isn't over yet: managing HD wallets when you have weak devices (phones) talking to weak servers (p2p nodes) is a difficult and fiddly piece of engineering. But we're making good progress and I'm hoping for a release later in the summer.

We have a new website! Check it out at and tell us what you think!

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Two bits of news today:

- We released bitcoinj 0.11.2, this is an important bugfix release that all wallets and users should be upgraded to.

- Tor integration has landed into git master:!topic/bitcoinj/XlL5jJs9ur8

It's not on by default yet because unfortunately Orchid has a couple of bugs but it should be good enough for beta testing. Look for a Tor option in your bitcoinj based wallet soon!

We have released bitcoinj 0.11.1. This is a bugfix release that resolves some minor issues with payment protocol verification, a Bloom filtering regression, and blocks dust transactions from entering the wallet. Combined with a new cleanup method, this should resolve the annoying 1Enjoy 1Sochi spam that has been appearing in peoples wallets lately.

All users are recommended to upgrade ASAP.

We released bitcoinj 0.11! It's an awesome release with more different contributors than any previous version. Wallets with the new features it enables should start to enter beta soon.

Some of my favourite highlights: payment protocol support, P2SH address support, the new PostgreSQL block store, a new GUI wallet template app that lets you quickly bring up a custom app that has wallet functionality for experimentation or contracts apps, a much improved micropayment channel sublibrary, and a new network stack that we'll start to exploit more thoroughly in the next release.

Things to look forward to in 0.12, if all goes well:

- HD wallets (with auto-upgrade)
- Integrated/out of the box Tor usage
- More decentralisation (less reliance on DNS seeds)
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