Truecrack is an open source Linux only tool optimized with Nvidia Cuda (Compute Unified Device Architecture ) technology, a computing platform able to process queries in parallel that can be used to crack Truecrypt volumes greatly speeding up brute force attacks, Truecrack will only work if the volume has been encrypted with the default Truecrypt settings RIPEMD160 and XTS block cipher mode based on AES. The software can read a list of passwords from a text file or generate a list of possible passwords from a charset of symbols defined by the user, a dictionary attack of 10,000 possible passwords with a length of 10 characters each will take 11 minutes to execute on an Intel Core i7 computer CPU, the same list of possible passwords in GPU mode (Nvidia Cuda technology) only takes 30 seconds to execute.
Truecrack will open a Truecrypt volume and retrieve the masterkey from its header section checking the success of the deciphering operation, if the password is right or wrong, querying the true and crc32 fields.
This is not the first tool designed to crack Truecrypt, while Truecrypt default settings are safe, for what I have seen in other similar tools they are all optimized to crack Truecrypt encryption having into account that the user did not change the default cipher (AES) or key derivation (RIPEMD160) and they do not work when keyfiles have been used. Choosing a strong passphrase should stop any brute force attack on your Truecrypt volume but if you would like to play the paranoid card it would be a good idea to change the default settings to something else, like a cascade algorithm, and add a keyfile.