Where P = plaintext, C = ciphertext, E = the encryption method, D = the decryption method, and k = the key. For those who like formulas, this process is sometimes written as: The encryption and decryption is based upon the type of cryptography scheme being employed and some form of key. Plaintext is encrypted into ciphertext, which will in turn (usually) be decrypted back into usable plaintext. In cryptography, we start with the unencrypted data, referred to as plaintext. Key exchange: The method by which crypto keys are shared between sender and receiver.Non-repudiation: A mechanism to prove that the sender really sent this message.Integrity: Assuring the receiver that the received message has not been altered in any way from the original.Authentication: The process of proving one's identity.Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver.
There are five primary functions of cryptography: In data and telecommunications, cryptography is necessary when communicating over any untrusted medium, which includes just about any network, particularly the Internet. It is no surprise, then, that new forms of cryptography came soon after the widespread development of computer communications. Some experts argue that cryptography appeared spontaneously sometime after writing was invented, with applications ranging from diplomatic missives to war-time battle plans.
when an Egyptian scribe used non-standard hieroglyphs in an inscription. BASIC CONCEPTS OF CRYPTOGRAPHYĬryptography the science of secret writing is an ancient art the first documented use of cryptography in writing dates back to circa 1900 B.C. Such mention is for example purposes only and, unless explicitly stated otherwise, should not be taken as a recommendation or endorsement by the author. (See Section A.4 for some additional commentary on this.)ĭISCLAIMER: Several companies, products, and services are mentioned in this tutorial. The second is to provide some real examples of cryptography in use today. The first is to define some of the terms and concepts behind basic cryptographic methods, and to offer a way to compare the myriad cryptographic schemes in use today. The reader is advised, then, that the topics covered here only describe the first of many steps necessary for better security in any number of situations. But it is important to note that while cryptography is necessary for secure communications, it is not by itself sufficient.
One essential aspect for secure communications is that of cryptography. There are many aspects to security and many applications, ranging from secure commerce and payments to private communications and protecting health care information.
Keyed-Hash Message Authentication Code (HMAC)ĥ.20. Challenge-Handshake Authentication Protocol (CHAP)ĥ.19. The Advanced Encryption Standard (AES) and Rijndaelĥ.14. Public Key Certificates and Certification Authoritiesĥ.7. Since that time, this paper has taken on a life of its own.ģ.5. © 1998-2021 A much shorter version of this paper first appeared in Handbook on Local Area Networks (Auerbach, Sept.