Crytography and Computer Security

What is cryptography?

Plaintext and Ciphertext - crpytanalysis - two kinds of cryptography

Caesar's Cipher

This a a Substitution Cipher approach. Compare to transposition cipher approaches.

Key Management

This is the key problem with conventional encryption. Why is this so?

Solution: Public Key Cryptography.

Public Key Cryptography (PKC) is an asymmetric scheme that uses a pair of keys. What is the primary benefit of PKC? What is the pair called? Conventional cryptography is symmetric.

Digital Signatures.

What is a digital signature? Why are they so important? What do you use to find out if a document purportedly sent by Alice was actually send and signed by her and not someone impersonating her? What does Alice use to sign her document? What do you use the verify she signed it?

Vigenere ciphers

Do they really help to produce Frequency Analysis immunity?

aaaaaa mississippi aaaaaa panthersuniuniuniuni aaaaaaaaaaaa PLAINTEXT
holmes twdemkzwabm sholme hhbetijziyuyfpiyuyfp olmesholmesh CIPHERTEXT

As you can see, the key was holmes as in Sherlock HOLMES
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