(D5) Cryptography (D6) Data Communication (D7) Malicious Codes and Malware

Part 1

The cryptography comes from the words, "crypto" hide and "graphein" write, then the meaning is "the art of hiding messages." Cryptography has been used throughout the whole history of humanity. By their nature, had been used mainly in wars or media in national security agencies influential countries worldwide, but today is widely used in many common applications, such as Internet, telephone, radio, television, satellite communications, etc.

The main goal of cryptography send a message in a "hidden", called " encryption "or" encrypted "and that only the receiver with a key or secret key to" decrypt "and read its contents. Basically we must ...