---
# This file is licensed under the MIT License (MIT) available on
# http://opensource.org/licenses/MIT.
# Text originally from Bitcoin Core project
# Metadata and small formatting changes from Bitcoin.org project

## Please see _releases/0.10.0.md for a release template
required_version: 0.8.1
optional_date: 2013-03-18
title: Bitcoin-Qt version 0.8.1 released
show_toc: true

---

<div class="post-content" markdown="1">

Bitcoin-Qt version 0.8.1 is now available from:
  <http://sourceforge.net/projects/bitcoin/files/Bitcoin/bitcoin-0.8.1/>

This is a maintenance release that adds a new network rule to avoid
a chain-forking incompatibility with versions 0.7.2 and earlier.

Please report bugs using the issue tracker at github:
  <https://github.com/bitcoin/bitcoin/issues>



How to Upgrade
--------------

If you are running an older version, shut it down. Wait
until it has completely shut down (which might take a few minutes for older
versions), then run the installer (on Windows) or just copy over
/Applications/Bitcoin-Qt (on Mac) or bitcoind/bitcoin-qt (on Linux).

If you are upgrading from version 0.7.2 or earlier, the first time you
run 0.8.1 your blockchain files will be re-indexed, which will take
anywhere from 30 minutes to several hours, depending on the speed of
your machine.

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<div class="toccontent-block boxexpand expanded" markdown="1">

0.8.1 Release notes
===================

The 0.8.1 release has just two changes from the 0.8.0 release:

1. A new block-acceptance rule that will be enforced from 21 March 2013 until
15 May 2013 to prevent accepting blocks that fail to validate on pre-0.8 peers.

2. A new compiled-in checkpoint at block number 225,430 -- the first block
of the 11 March 2013 chain fork.


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<div class="toccontent-block boxexpand expanded" markdown="1">

0.8.0 Release notes
===================

Incompatible Changes
--------------------

This release no longer maintains a full index of historical transaction ids
by default, so looking up an arbitrary transaction using the getrawtransaction
RPC call will not work. If you need that functionality, you must run once
with -txindex=1 -reindex=1 to rebuild block-chain indices (see below for more
details).

Improvements
------------

Mac and Windows binaries are signed with certificates owned by the Bitcoin
Foundation, to be compatible with the new security features in OSX 10.8 and
Windows 8.

LevelDB, a fast, open-source, non-relational database from Google, is
now used to store transaction and block indices.  LevelDB works much better
on machines with slow I/O and is faster in general. Berkeley DB is now only
used for the wallet.dat file (public and private wallet keys and transactions
relevant to you).

Pieter Wuille implemented many optimizations to the way transactions are
verified, so a running, synchronized node uses less working memory and does
much less I/O. He also implemented parallel signature checking, so if you
have a multi-CPU machine all CPUs will be used to verify transactions.

New Features
------------

"Bloom filter" support in the network protocol for sending only relevant transactions to
lightweight clients.

contrib/verifysfbinaries is a shell-script to verify that the binary downloads
at sourceforge have not been tampered with. If you are able, you can help make
everybody's downloads more secure by running this occasionally to check PGP
signatures against download file checksums.

contrib/spendfrom is a python-language command-line utility that demonstrates
how to use the "raw transactions" JSON-RPC api to send coins received from particular
addresses (also known as "coin control").

New/changed settings (command-line or bitcoin.conf file)
--------------------------------------------------------

dbcache : controls LevelDB memory usage.

par : controls how many threads to use to validate transactions. Defaults to the number
of CPUs on your machine, use -par=1 to limit to a single CPU.

txindex : maintains an extra index of old, spent transaction ids so they will be found
by the getrawtransaction JSON-RPC method.

reindex : rebuild block and transaction indices from the downloaded block data.

New JSON-RPC API Features
-------------------------

lockunspent / listlockunspent allow locking transaction outputs for a period of time so
they will not be spent by other processes that might be accessing the same wallet.

addnode / getaddednodeinfo methods, to connect to specific peers without restarting.

importprivkey now takes an optional boolean parameter (default true) to control whether
or not to rescan the blockchain for transactions after importing a new private key.

Important Bug Fixes
-------------------

Privacy leak: the position of the "change" output in most transactions was not being
properly randomized, making network analysis of the transaction graph to identify
users' wallets easier. 

Zero-confirmation transaction vulnerability: accepting zero-confirmation transactions
(transactions that have not yet been included in a block) from somebody you do not
trust is still not recommended, because there will always be ways for attackers to
double-spend zero-confirmation transactions. However, this release includes a bug
fix that makes it a little bit more difficult for attackers to double-spend a
certain type ("lockTime in the future") of zero-confirmation transaction.

Dependency Changes
------------------

Qt 4.8.3 (compiling against older versions of Qt 4 should continue to work)


Thanks to everybody who contributed to the 0.8.0 release:
---------------------------------------------------------

- Alexander Kjeldaas
- Andrey Alekseenko
- Arnav Singh
- Christian von Roques
- Eric Lombrozo
- Forrest Voight
- Gavin Andresen
- Gregory Maxwell
- Jeff Garzik
- Luke Dashjr
- Matt Corallo
- Mike Cassano
- Mike Hearn
- Peter Todd
- Philip Kaufmann
- Pieter Wuille
- Richard Schwab
- Robert Backhaus
- Rune K. Svendsen
- Sergio Demian Lerner
- Wladimir J. van der Laan
- burger2
- default
- fanquake
- grimd34th
- justmoon
- redshark1802
- tucenaber
- xanatos
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