Dogs in warfare have a long history starting in ancient times. From war dogs trained in combat to their use as scouts, sentries and trackers, their uses have been varied and some continue to exist in modern military usage.
Encryption is the coding or scrambling of information so that it can only be decoded and read by someone who has the correct decoding key. Encryption is used in secure Web sites as well as other mediums of data transfer. If a third party were to intercept the information you sent via an encrypted connection, they would not be able to read it.
In cryptography and steganography, deniable encryption is encryption that allows its users to convincingly deny the fact that the data is encrypted or, assuming that the data is obviously encrypted, its users can convincingly deny that they are able to decrypt it.