• # Cryptography - useful links

Show Host: Mike Rodrick

Show Instructor: Sean Philip Oriyano

Episode 1 - Cryptography Overview
Introduction

Episode 2 - History Of Cryptography

Episode 3 - The Language of Cryptography

Topics

• Algorithm Explained: A finite set of steps to resolve a particular problem.
ciphertext: Scramble unreadable message after Encryption
key: The means by which you encoded the message

• Example of Caesar Cipher:
BEN [plaintext] = EHQ: [ciphertext] KEY equals [shift by 3]
B becomes: shift1 = C, shift2 = D, shift3 = E, so B becomes E
• Encryption explained
Decryption explained
Symmetric explained
Asymmetric explained
Out of band: (ie sending the key and data seperate ways: email date, ring person with key to decode)
Secure Channel
one way function (hashing. message digest)
Trapdoor function
types of ciphers:

• stream cipher
Block cipher
• Substitution Cipher
Scytale (pronounced: sit - al - ee)
Criptogram (typically a puzzle or game)

Episode 4 - Components of Cryptography

Episode 5 - Algorithms and Ciphers

Example of symmetric & asymmetric by Ben from Wikipedia (1)

• symmetric:
Alice first puts the secret message in a box, and locks the box using a padlock to which she has a key. She then sends the box to Bob through regular mail. When Bob receives the box, he uses an identical copy of Alice's key (which he has somehow obtained previously, maybe by a face-to-face meeting) to open the box, and reads the message. Bob can then use the same padlock to send his secret reply.

• Asymmetric:
In an asymmetric key system, Bob and Alice have separate padlocks. First, Alice asks Bob to send his open padlock to her through regular mail, keeping his key to himself. When Alice receives it she uses it to lock a box containing her message, and sends the locked box to Bob. Bob can then unlock the box with his key and read the message from Alice. To reply, Bob must similarly get Alice's open padlock to lock the box before sending it back to her.