FreeOTFE4PDA is a free, open source, "on-the-fly" (OTFE) transparent disk encryption program.

Using this software, you can create one or more "virtual memory cards" on your PDA - anything written to which will be automatically, and securely, encrypted before being stored.

Features include:

- Source code freely available
- Easy to use; full wizard included for creating new volumes
- Powerful: Supports numerous hash/encryption algorithms, and provides a greater level of flexibility than a number of other (including commercial!) OTFE systems
- Hash algorithms include: MD5, SHA-512, RIPEMD-160, Tiger and many more
- Cyphers include AES (256 bit), Twofish (256 bit), Blowfish (448 bit), Serpent (256 bit) and many more
- "Hidden" volumes may be concealed within other FreeOTFE volumes, providing "plausible deniability"
- Encrypted volumes have no "signature" to allow them to be identified as such
- Modular design allowing 3rd party drivers to be created, incorporating new hash/cypher algorithms
- Supports password salting (up to 512 bits), reducing the risks presented by dictionary attacks.
- Keyfile support included; store volumes and their associated metadata separately.
- Uses per-sector IVs, including support for ESSIV
- Volume file timestamps and attributes are reset after dismounting, increasing "plausible deniability"
- Plus more...!

A PC version is also available, allowing data encrypted on your PC to be read/written on your PDA, and vice versa