Free open source on-the-fly encryption software
Most operating systems, including Windows, can be configured to write debugging information and contents of the system memory to so-called memory dump files (also called crash dump files) when an error occurs (system crash, “blue screen,” bug check). Therefore, memory dump files may contain sensitive data. TrueCrypt cannot prevent cached passwords, encryption keys, and the contents of sensitive files opened in RAM from being saved unencrypted to memory dump files. Note that when you open a file stored on a TrueCrypt volume, for example, in a text editor, then the content of the file is stored unencrypted in RAM (and it may remain unencrypted in RAM until the computer is turned off). Also note that when a TrueCrypt volume is mounted, its master key is stored unencrypted in RAM. Therefore, you must disable memory dump file generation on your computer at least for each session during which you work with any sensitive data and during which you mount a TrueCrypt volume. To do so in Windows XP or later, right-click the ‘Computer’ (or ‘My Computer’) icon on the desktop or in the Start Menu, and then select Properties -> (on Windows Vista or later: -> Advanced System Settings ->) Advanced tab -> sectionStartup and Recovery -> Settings -> section Write debugging information -> select (none) -> OK.
Note for users of Windows XP/2003: As Windows XP and Windows 2003 do not provide any API for encryption of memory dump files, if the system partition/drive is encrypted by TrueCrypt and your Windows XP system is configured to write memory dump files to the system drive, the TrueCrypt driver automatically prevents Windows from writing any data to memory dump files.