Subvenio Computing

A Crash Course in Cryptography Part II – Symmetric Ciphers

Posted on: May 3rd, 2010, Filed under: General No Comments »

AES, cipher, cryptanalysis, cryptography, DES, DMCA, hash, MD5, monoalphabetic, password, polyalphabetic, rainbow tables, SHA-1, symmetric, vigenère

Today we will be delving into symmetric ciphers. I will remind you that this course is an introductory one. That means we won’t be digging deeply into the specifics. Yes, we will talk a little about the algorithms and their applications, however it will mostly be abstract. For instance we will talk about what a hash is, but not pick out the mathematical differences between SHA-1 and MD5.

What is a symmetric cipher? Symmetric, secret, private key, these are all synonyms for a specific class of cryptography. Symmetric ciphers all have one thing in common, a secret. That’s it. The encryption is only as strong as this secret and who knows it. As the old saying goes, “Three can keep a secret if two of them are dead.” That said, let’s get one with it and find out what implications that has.
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