For as long as modern computers have been around, they have been associated with encryption in one way or another. It is no coincidence that the first semi-programmable computer, Colossus, was developed to decrypt messages during the Second World War. Encryption relies on encoding information in a way that makes it difficult to decode without either a key (cipher) or an awful lot of mathematical muscle. The longer the length of the cipher (in bits), the more difficult it will be to break. Although there are many encryption techniques that are unbreakable in practice, there are very few that are unbreakable in theory, given enough time or processing power.

Encryption techniques separate into two main types, explains Bernard Parsons, chief technology officer at security software company BeCrypt. Symmetric encryption dates back to the Roman empire and beyond, but asymmetric encryption is more recent.

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