CS458 Lecture Notes - Lecture 5: Authenticated Encryption, Stream Cipher, Block Cipher
2 Dec 2014
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Document Summary
Building blocks: cryptography contains three major types of components, con dentiality components, preventing eve from reading alice"s messages, integrity components, preventing mallory from modifying alice"s messages without being detected, authenticity components, preventing mallory from impersonating alice. Eve can do: with weaker systems, there are shortcuts to nding the key, example: newspaper cryptogram has. 403,291,461,126,605,635,584,000,000 possible keys: but you don"t try them all; it"s way easier than that! Secret-key encryption: secret-key encryption is the simplest form of cryptography, also called symmetric encryption, used for thousands of years, the key alice uses to encrypt the message is the same as the key bob uses to decrypt it. Secret-key encryption: eve, not knowing the key, should not be able to recover the plaintext. Computational security: in contrast to otp"s perfect or. Some data points: one computer can try about 17 million keys per second, a medium-sized corporate or research lab may have 100 computers, the boinc project has 13 million computers.
