Practical cryptography

Several standards for data encryption and protection have been created in cryptography. One of them is AES (Advanced Encryption Standard), a very strong symmetric cipher, which is used (among others) by American military and diplomatic corps. Despite many years of scientific research, no real weak points of AES cipher have been found. Other important standard is SHA-2, a hash algorithm, which can be used to protect data integrity (=that no one has changed the data in any way).

A basic rule concerning ciphers is so-called Kerckhoff principle. By this principle, a detailed knowledge of the cipher must not help the attacker to retrieve the encrypted information; all security must lie in used key.

In autumn 2005, both AES and SHA-2 standards respected Kerckhoffs principle.

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