Classical Cryptography

Cryptography is about communication in the presence of adversaries. ¹ The best-known example is that of confidentiality or privacy—maintaining secrecy in communications over an unsecured channel. The cryptographic solution is encryption, which modifies the data in an attempt to render the communication unintelligible to all but the intended recipients. Cryptography can be regarded as the science of mathematical techniques for protecting data (from malicious or unauthorized actions) by transforming the data itself.