Kremlin is the perfect encryption tool for the job.
BS Editor: Kremlin Encrypt provides an easy-to-use interface to powerful cryptography. You can Encrypt Files with one of six algorithms, including RC4 and Blowfish.

Read more about cryptography basics or an overview of cryptographic algorithms.

Encryption with Kremlin is easy to do and completely transparent. For example: to encrypt a file, just right-click on the file and choose Kremlin Encrypt.

After you enter your passphrase, it is hashed with a 64-bit random salt using SHA1 (implemented as per the FIPS 180-1 standard) hash Algorithm. This produces a 160 bit digest, which is then used as the key to the encryption algorithm. If a block encryption algorithm is selected, encryption is performed in enhanced Cipher Block Chaining (CBC) mode.

The encrypted kgb file can be transferred across the platforms! For example you can encrypt the file on PC and then copy and decrypt it on MAC.

Kremlin Decrypt allows you to decrypt the files you have encrypted. To use it, just double-click on the encrypted .kgb file. You should then enter your passphrase. It will appear obscured with stars (optionally disabled) to prevent other people from reading it off your screen.

By Default, Kremlin decrypts all files in the .kgb archive. If you would like to choose which files to decrypt, uncheck the Decrypt All button and choose which files you would like to decrypt. you can free download Kremlin Encryption and Security Suite 2.21 now.