TrueCrypt unfortunately doesn't exist in my usual repositories. Building it in Fedora requires having the kernel sources installed and a one-line edit to the build script to properly set the path of the kernel sources. Once built, TrueCrypt works fine on Fedora.

Get kernel sources
If you already have a kernel source tree on your system, you can skip this step. Or, if you think you do and realize you don't when things fail later, you can always come back to this step.

To get the kernel sources you'll need to do the following:

$ sudo yum -y install kernel-devel yum-utils redhat-rpm-config unifdef
$ cd /usr/src
$ sudo yumdownloader --source kernel --enablerepo updates-source
$ sudo rpm -ivh kernel*.src.rpm
$ sudo rpmbuild -bp --target=`uname -m` /usr/src/redhat/SPECS/kernel-2.6.spec

At this point, you should have your kernel source tree located somewhere like: /usr/src/redhat/BUILD/kernel-2.6.20/linux-2.6.20.x86_64

Get TrueCrypt
Go to the TrueCrypt Download Page and download Other (source code) under Linux.

$ tar xzvf truecrypt*code.tar.gz
$ truecrypt*/Linux/
$ vi build.sh

You can substitute vi in the above example with your favorite text editor.

Find the following line:

KERNEL_SRC=/usr/src/linux-source-$KERNEL_VER

You need to change the path to the actual path where your kernel sources are. So, the line should look like:

KERNEL_SRC=/usr/src/redhat/BUILD/kernel-2.6.20/linux-2.6.20.x86_64

Then save it and you're ready to build and install TrueCrypt.

Build and Install TrueCrypt
Just run the scripts provided:

$ sudo ./build.sh && sudo ./install.sh

Note that the build script takes quite some time to build. (With my 2.2GHz Athlon64 with 1GB RAM, I had enough time to get a cup of coffee.)

Use TrueCrypt
Instead of reinventing the wheel, I'll just link you to the following pages:

• TrueCrypt on Linux HOWTO with XFS and ext2/ext3 volumes
• HOWTO Truecrypt - Gentoo Linux
• TrueCrypt Manual Page