.DCO files are virtual disk files that have been encrypted with the application 'DisCryptor'. 'DisCryptor' is a software utility that will securely encrypt important data. .DCO files are similar to .DCF files, but .DCO files are saved as a virtual disk instead of a standard file archive. DCO files may be encrypted using any number of algorithms, including, but not limited to, Blowfish, Twofish, CAST5, CAST6, MARS, RC5, RC6, Rijndael (AES), or Serpent. .DCO files can also be decrypted by an authorized user with DisCryptor Personal or Enterprise software.