shannon and 5 good criteria of a good cipher
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a brief introduction of Shannon his 5 good criteria of a cipherTRANSCRIPT
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(April 30, 1916 – February 24, 2001)
American mathematician, electronic engineer, and cryptographer.
Graduated from MIT known as "the father of
information theory“.
Claude Elwood Shannon Shannon Biography
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Plaintext: text to be protected
Cipher (or cypher): algorithm for performing encryption or decryption
Ciphertext: encrypted/decrypted plaintext.
Terminology
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1. The amount of secrecy needed should determine the amount of labor appropriate for the encryption and decryption. Need of more security, needs more encryption
5 criteria of a good cipher:
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2. The set of keys and the enciphering algorithm should be free from complexity.
5 criteria of a good cipher:
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3. The implementation of the process should be as simple as possible.
5 criteria of a good cipher:
Undermining security
Complexity implementati
on
Message Transmission
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4. Errors in ciphering should not propagate and cause corruption of further information in the message. one error should not throw off the entire process
5 criteria of a good cipher:
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5. The size of the enciphered text should be no larger than the text of the original message.
5 criteria of a good cipher:
Longer ciphertext :
More space of storageEasier detection of pattern by Cryptanalysis
Longer time to communicate
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Shannon developed these criteria before modern digital computers.
Some the concern he expressed, is not a limitation anymore.
We don’t need to implement a simple cipher with modern fast computers, whereas complexity of implementation has become easier
BUT
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World is not safe, be careful of your information and privacy
Be secure