A puzzle concerning techniques for secure communication in the presence of (hostile) third parties. Do NOT use this for simple "crack the code" problems; use [cipher] instead.
Cryptography is the art of secure communication in the presence of (hostile) third parties.
More precisely, Cryptography
- constructs and analyzes protocols that block third parties
- deals with aspects in information security as data confidentiality, data integrity, authentication
- applies techniques from mathematics, computer science, and electrical engineering.
Everyday applications of cryptography include ATM cards, computer passwords, and electronic commerce.
There is a Stack Exchange site dedicated to Cryptography, please use this if your questions are of a more serious nature.