Cryptography

**Pages:**

 * 1) Introduction to Cryptography
 * 2) Example(s) of Historical Cryptography, i.e. before computers.
 * 3) Introduction to Modern Cryptography
 * 4) Symmetric-key Cryptography
 * 5) Example/Interactive Activity
 * 6) Public-key Cryptography
 * 7) Example/Interactive Activity
 * 8) Hash Functions/One-way Cryptography
 * 9) Example/Interactive Activity
 * 10) Cryptanalysis
 * 11) Example/Interactive Activity

**Content:**
Vicki: We have some cryptography exercises already. How does this compare? Can we make this interactive?
 * 1) **//Introduction to Cryptography//** -- This page will have a brief explanation of cryptography, with possibly a short history of cryptography. This page will explain some of the importance of cryptography in the modern world.
 * 2) //**Example(s) of Historical Cryptography** --// This will have one or two examples of historical encryption systems, eg. the [|Caesar cipher]. An interactive demo of Caesar cipher should be implemented.
 * 3) //**Introduction to Modern Cryptography** --// Here we will see the ways cryptography is used in modern computer systems, eg. networks, financial systems, messaging, etc., symmetric-key cryptography, one-way cryptography, and public-key cryptography will have a brief introduction here, as well as cryptanalysis.
 * 4) //**Symmetric-key Cryptography** --//Explanation of symmetric-key cryptography, including block and stream ciphers, possibly with a basic interactive activity.
 * 5) Symmetric-key cryptography is a one-key crypto system in which two parties send secure messages using a shared secret key to both encrypt and decrypt a message. The issue with this is that both the sender and the receiver must have the key, and the sharing of this key can become a security issue.
 * 6) //Example/Interactive Activity --// Less basic interactive activity.
 * 7) //**Public-key Cryptography** --//Explanation of public-key cryptography, possibly with a basic interactive activity.
 * 8) Public-key cryptography is a two-key crypto system in which two parties may send secure messages through an non-secure communications channel without the use of a shared secret key. Instead, a separate key is used for encryption and decryption. Public-key cryptography is dependent on the existence of __one-way functions__. Public-key encryption typically uses these one way functions in order to create keys, one easy to compute, one difficult, often using the factorizations of very large prime numbers.
 * 9) __One-way function:__ A mathematical function that is easy to compute, but whose inverse is difficult to compute, eg. multiplication vs. factoring, exponentiation vs. logarithms.
 * 10) //Example/Interactive Activity//
 * 11) Examples -- RSA, Diffie-Hellman, DSA, ElGamal, ECC, PKCS, Cramer-Shoup, KEA, LUC
 * 12) Interactive Activity -- [|XOR cipher].
 * 13) //**Hash Functions/One-way Cryptography** --//Explanation of hash functions, and possibly a basic interactive activity.
 * 14) Hash functions don't use any keys, since the encrypted message is not able to be decrypted. Hash functions are often used to provide a digital fingerprint of a file's contents. They are also used to encrypt passwords and to measure the integrity of a file.
 * 15) //Example/Interactive Activity --// Examples: MD5, SHA-1, etc.
 * 16) //**Cryptanalysis** --//What cryptanalysis is, what it's used for, who uses it, etc.
 * 17) The goal of cryptanalysis is to discover flaws in the cryptographic methods of messagers in order to
 * 18) //Example/Interactive Activity --// Find some way to make an interactive cryptanalysis activity.

Mr. Weeks: I could only find the one ILM on Caesar cryptography but I probably missed some. If I understand it correctly, I think you only have to consider 25 alternatives to break the Caesar code. We have done XOR encryption with a pretty lengthy key in our programming class and we use MD5 to encrypt our passwords in the SQL database we use for our online voting at the high school. Maybe there could be an every-day-life example of encryption like remote keyless entry for cars. I don't know what the encryption is or how difficult it would be to understand, but students could relate to the need to make that secure.

Vicki: It would be nice to have someone who liked cryptography look at these ILMs.

Caesar/Vinegere Encryption: http://csilm.usu.edu/lms/nav/activity.jsp?sid=__shared&cid=emready@encryption&lid=3 Transposition: http://csilm.usu.edu/lms/nav/activity.jsp?sid=__shared&cid=emready@encryption&lid=5 These could be make easier to use. The transposition is too slow. Because encryption and decryption are mixed, it isn't clear what to provide. The cells don't force the right type of entry or allow cutting and pasting.