Foundations of Cryptography

The basic idea of cryptography is to take a plaintext message, combine it with a key, and get ciphertext output. Once ciphertext is generated, its secrecy is not that important as long as the key is secret. Only those with the key to decrypt the message are able to read it. The process of encrypting plaintext messages is encryption. Getting the plaintext back from the ciphertext is decryption. The process of trying to break a cryptosystem is cryptanalysis.

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