GSMK CryptoPhone for Windows Mobile offers secure end-to-end encrypted voice calls using the same 4096-bit Diffie-Hellman key exchange and 256-bit AES and Twofish symmetric encryption as all other GSMK CryptoPhone products. Unlike GSMK CryptoPhone secure mobile phones that feature a hardened operating system, secure storage, and secure messaging, GSMK CryptoPhone for Windows Mobile is a software-only voice encryption application and thus offers no protection against targeted attacks against the mobile device itself.