Cryptography is the science of keeping privacy in communications. According to some historians, the cryptography exists since the writing itself, which exists since more than 4000 years. In this course we first are going to discuss about the so-called classical cryptography, also known as the symmetric cryptography. This one has persisted for centuries. Second we are going to dive into the so-called asymmetric cryptography which emerged in the 1970s and is more complex than the former one.
In communication between two people, the information is conveyed from the sender to the recipient through a communication channel, such as over the mail, internet, telephone, air. In most of communications, channels are not secured. That’s where the cryptography comes into play. An encryption algorithm (also called cipher) turns an understandable information, called the plaintext, into an incomprehensible one for unconcerned parties, called cryptogram or ciphertext.
Cryptography has nowadays other applications than only ensuring privacy in communications. For example, cryptography is used in DRM (digital rights management) for controlling the use of copyrighted content (music, book). These DRM restrict the amount of copies or plays of numeric files. Cryptocurrencies are using cryptography as well.