[Bitcoin-development] bitcoinj 0.7 released

[Bitcoin-development] bitcoinj 0.7 released

[Mike Hearn]

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I'm pleased to announce the release of version 0.7 of the bitcoinj Java
library for working with Bitcoin. Bitcoinj forms the foundation of
MultiBit, Bitcoin Wallet for Android, SatoshiDice and more.

To get bitcoinj 0.7, check out our source from git and then run *git reset
--hard a9bd8631b904*. This will place you on the 0.7 release in a secure
manner. This paragraph was written on Tuesday 19th February 2013 and is
signed with the following key, which will be used in all release
announcements in future: 16vSNFP5Acsa6RBbjEA7QYCCRDRGXRFH4m.

Signature for the last
paragraph: IMvY1FsQobjU2t83ztQL3CTA+V+7WWKBFwMC+UWKCOMyTKA+73iSsFnCHdbFjAOEFMQH/NvJMTgGeVCSV/F9hfs=

If you want to, you can check that the original announcement mail sent to
bitcoinj@googlegroups.com is correctly signed with the google.com DKIM key,
to establish a full chain of trust.

*Release notes*

   - Thanks to Matt Corallo, we now support a* fully verifying mode* in
   addition to simplified verification. This is a tremendous amount of work
   that wouldn't have happened without Matt! Right now, we strongly discourage
   anyone from using it for mining (which is not supported out of the box
   anyway). Use it in a production environment only if you know what you're
   doing and are willing to risk losing money. If you do use it, let us know
   so we can contact you when problems are discovered. Read the documentation
   carefully before you begin.
   - Also thanks to Matt, *Bloom filtering* is now implemented and
   activated by default. When bitcoinj connects to a peer that supports Bloom
   filtering, only transactions relevant to the wallet will be downloaded
   which makes bandwidth usage scale with the size of your wallet, not global
   system activity. A configurable false positive ratio allows you to trade
   off bandwidth vs privacy. App developers don't need to do anything to take
   advantage of this, it is enabled automatically.
   - PeerGroup now pings its peers and calculates moving averages of the
   ping times. Ping time, versions and block heights are taken into account
   when selecting the peer to download the chain from.
   - You can now customize which outputs the wallet uses to create spends.
   The new default coin selector object allows you to spend unconfirmed change
   as long as it's been seen propagating across the network, addressing a
   common end-user pain point in wallet apps.
   - Optimized networking code for faster startup.
   - A new PeerMonitor example app shows how to put properties of connected
   peers into a GUI.
   - The Wallet is now decoupled from the BlockChain using the new
   BlockChainListener interface. This will simplify the development of some
   apps that want to process transactions but not maintain an actual wallet.
   - The dependencies of broadcast transactions are now downloaded and risk
   analyzed. At the moment they are only being checked for having a timelock.
   In future we may also analyze tree depth. The goal is to make certain kinds
   of protocol abuse harder. Wallets will reject timelocked transactions by
   default, this can be overridden via a property.
   - You can now create timelocked transactions with
WalletTool?<http://code.google.com/p/bitcoinj/w/edit/WalletTool> if
   you want to.
   - Compressed public keys are now used by default.
   - Support testnet3
   - Support bitcoin-qt compatible message signing and verification.
   - ECDSA key recovery is now implemented and allows you to obtain the
   public key from an extended signature. If the signature is not extended
   then there are multiple key possibilities returned.
   - Many bugfixes and minor improvements

API changes:

   - ECKey.sign() now takes a Sha256Hash as an argument and returns an
   ECDSASignature object in response. To get DER encoded signatures, use
   the encodeToDER() method of ECDSASignature.
   - ECKey.publicKeyFromPrivate now takes an additional compressed
   parameter.
   - PeerGroup.start()/PeerGroup.shutDown() now run asynchronously and
   return futures you can use to wait for them. You cannot restart a
   PeerGroup once it has been shut down any more.

*Credits*
*
*
Thanks to Matt Corallo (a.k.a. BlueMatt) for his huge contributions to this
release.

As always, thanks to Andreas Schildbach for his thorough testing, ideas and
high volume of quality bug reports. Also thanks to Jim Burton for the same
reasons.

Finally thanks to Ben (piuk) of blockchain.info for funding the ECDSA key
recovery feature.

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