Inside Bitcoin
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The code behind the network, with room to understand it.
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1Bitcoin version 0.4.0 is now available for download at:2http://sourceforge.net/projects/bitcoin/files/Bitcoin/bitcoin-0.4.0/4The main feature in this release is wallet private key encryption;5you can set a passphrase that must be entered before sending coins.6See below for more information; if you decide to encrypt your wallet,7WRITE DOWN YOUR PASSPHRASE AND PUT IT IN A SECURE LOCATION. If you8forget or lose your wallet passphrase, you lose your bitcoins.9Previous versions of bitcoin are unable to read encrypted wallets,10and will crash on startup if the wallet is encrypted.12Also note: bitcoin version 0.4 uses a newer version of Berkeley DB13(bdb version 4.8) than previous versions (bdb 4.7). If you upgrade14to version 0.4 and then revert back to an earlier version of bitcoin15the it may be unable to start because bdb 4.7 cannot read bdb 4.816"log" files.19Notable bug fixes from version 0.3.24:21Fix several bitcoin-becomes-unresponsive bugs due to multithreading22deadlocks.24Optimize database writes for large (lots of inputs) transactions25(fixes a potential denial-of-service attack)28Wallet Encryption30Bitcoin supports native wallet encryption so that people who steal your31wallet file don't automatically get access to all of your Bitcoins.32In order to enable this feature, choose "Encrypt Wallet" from the33Options menu. You will be prompted to enter a passphrase, which34will be used as the key to encrypt your wallet and will be needed35every time you wish to send Bitcoins. If you lose this passphrase,36you will lose access to spend all of the bitcoins in your wallet,37no one, not even the Bitcoin developers can recover your Bitcoins.38This means you are responsible for your own security, store your39passphrase in a secure location and do not forget it.41Remember that the encryption built into bitcoin only encrypts the42actual keys which are required to send your bitcoins, not the full43wallet. This means that someone who steals your wallet file will44be able to see all the addresses which belong to you, as well as the45relevant transactions, you are only protected from someone spending46your coins.48It is recommended that you backup your wallet file before you49encrypt your wallet. To do this, close the Bitcoin client and50copy the wallet.dat file from ~/.bitcoin/ on Linux, /Users/(user51name)/Application Support/Bitcoin/ on Mac OSX, and %APPDATA%/Bitcoin/52on Windows (that is /Users/(user name)/AppData/Roaming/Bitcoin on53Windows Vista and 7 and /Documents and Settings/(user name)/Application54Data/Bitcoin on Windows XP). Once you have copied that file to a55safe location, reopen the Bitcoin client and Encrypt your wallet.56If everything goes fine, delete the backup and enjoy your encrypted57wallet. Note that once you encrypt your wallet, you will never be58able to go back to a version of the Bitcoin client older than 0.4.60Keep in mind that you are always responsible for your own security.61All it takes is a slightly more advanced wallet-stealing trojan which62installs a keylogger to steal your wallet passphrase as you enter it63in addition to your wallet file and you have lost all your Bitcoins.64Wallet encryption cannot keep you safe if you do not practice65good security, such as running up-to-date antivirus software, only66entering your wallet passphrase in the Bitcoin client and using the67same passphrase only as your wallet passphrase.69See the doc/README file in the bitcoin source for technical details70of wallet encryption.
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