mirror of
https://github.com/jackyzha0/quartz.git
synced 2025-12-26 06:14:06 -06:00
48 lines
1.1 KiB
Markdown
48 lines
1.1 KiB
Markdown
---
|
|
title: "05-crypography"
|
|
aliases:
|
|
tags:
|
|
- lecture
|
|
- comp210
|
|
---
|
|
|
|
# news
|
|
- zodiac killer code cracked
|
|
- twitter leak
|
|
|
|
# Brief history
|
|
- study of secret messages
|
|
- confidentiality of [cia-triad](notes/cia-triad.md)
|
|
- also small role in integrity (authentication of message, and sender)
|
|
- history of cyprtopgraphy is interwined with information technology
|
|
|
|
Language use for communication seems to be part of human nature: perhaps the use of covert lanuage is too
|
|
|
|
## need for confidentiality
|
|
"nothing to hide: nothing to fear" look at edward snowdens corrolary
|
|
|
|
We all have legit needs for privacy. Cryptography provides technical measure for ensuring this privacy.
|
|
|
|
## history
|
|
- caesar cipher
|
|
- simple substitution scheme (rotation)
|
|
- vulnerable to cryptanalysis
|
|
|
|
# General process
|
|
- encrypt
|
|
- plaintext + key => ciphertext
|
|
- key is a secret
|
|
- decrypt
|
|
- ciphertext + key => plaintext
|
|
|
|
mathmatically
|
|
- c = e(p, k)
|
|
- p = d(c, k)
|
|
|
|
# Terminology
|
|
- copy later
|
|
|
|
# Plaintext
|
|
refers to unencypted message. In the digital age the messages are often not plain text (ascii, unicode, etc).
|
|
|
|
digital crypto schemes normally work on the binary data (images, .docs, .txt, mp4 etc.) |