about a month ago my friend said that cryptography is mathematics. I immediately re-think cryptography is really mathematics? mathematics is widely used in cryptography (and other subjects) but to assumes that the cryptography is mathematics I think that’s too excessive.

I think cryptography is art and science of to secure the message (more precisely to make the message has a fourth aspect of cryptography: confidentiality, integrity, authentication, and non-repudiation) about how to achieve them you can use math problems, a chemical substance used as an invisible-ink , or with our knowledge of light properties uses light as OTP(One Time Pad) like quantum crypthograpy

so cryptography is the applicative science that uses various other disciplines to achieve these four aspects of cryptography and** not only mathematics **.