Encryption surrounds us imperceptibly every time we use mobile communications, online banking, online services and the like. Meanwhile the demand for efficient encryption is growing daily. In this thesis, we present authenticated encryption, which is one of the most powerful tools for ensuring secure communications, since it provides both privacy and authenticity. We show which kind of attacks a system like that is effective against and explain why. We describe message authentication codes and show how they assure data integrity. Finally, we present different approaches to constructing authenticated encryption schemes: generic compositions which combine an encryption scheme and a message authentication code, and integrated schemes. Two algorithms that realize such systems are then presented: GCM and OCB.
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