Native Android encryption presents some limitations when you want to easily and securely exchange your data to your PC.
However, using Truecrypt you can easily set most Android smartphones to act as encrypted mobile storage devices.
Why bother with those easy to lose and rarely encrypted USB Flash Drives when you always have your smartphone with you?
What You Will Need
Personal Computer. (Windows, Linux, OSX, BSD ..doesn't matter)
Android smartphone or mobile device that accepts MicroSD storage and has a USB connector.
Decently size MicroSD storage card (the larger the better).
Some basic knowledge of setting up partitions on Windows, Linux, OSX, or BSD.
Step #1 - Backup Your Data!
If you have any data that you don't want to risk losing, you need to backup it up off your mobile device's MicroSD" card.
If this data is protected with native Android encryption you will first need to decrypt it.
Step #2 - Wipe The MicroSD Partition Table
Connect your mobile device via USB to your computer and fire up your favorite partitioning tool.
Using this tool, first remove all partitions off the storage device that respresents the MicroSD storage card within the device.
Step #3 - Set Up partition for your Android Device
Next, we'll want to set up a partition that the mobile device can use.
You want to size this partition to be enough for basic use but also leave enough remaining space on the storage media for your encrypted storage needs.
Since I have a 32GB MicroSD card, I have chosen to slice off 8GB for my phone.
This first partition needs to be formatted as a FAT partition to ensure compatabilitiy with your Android device.
Step #4 - Set Up partition for encrypted Truecrypt volume
Now add a second partition that covers the remaining space on your storage media.
After you've done this your partition layout should look something like this:
With your new partition table in place, you can now fire up Truecrypt to use the second partition an encrypted volume.
Select Create a volume within a partition/drive.
Make sure to select the second partition that you created on your Android internal storage media.
Make a mistake here and you can wipe your data. Be careful!
Follow instructions to set up a password and select the encryption and hashing algorithm you wish to use for your encrypted volume.
Note: Make sure that your password is strong!!
After TrueCrypt has finished setting up the encrypted volume on your partition you will be able to access it.
Simply select the appropriate encrypted device partition (sdd2 in this example) and input your passphrase to mount the drive on your PC.
Voila! You now have convenient portable encrypted storage that goes where you go