Cryptography (from
Greek kryptós, "hidden", and
gráphein, "to write") is the study of the principles and techniques by which information can be concealed in ciphers
and later revealed to legitimate users employing the encryption key (see
/Key), but in which it is either impossible or computationally infeasible for an unauthorized person to do so.
More specifically, cryptography has four main goals:
- message confidentiality
- It should only be possible for those authorised to read a message to do so. It should be impossible (or at least extremely difficult) for unauthorised persons to obtain the message contents.
- message integrity
- The contents of a message should not be able to be altered once transmitted.
- authentication
- The receiver of a message should be able to identify the sender and verify that they did transmit the message.
- non-repudiation
- The sender should not be able to deny sending the message.
- Cryptology -- Cryptanalysis
- Hash function: MD5 -- SHA-1
- Public Key Cryptosystems (Asymmetric Algorithms): RSA -- Diffie-Hellman -- Elliptic curve cryptography
- Secret Key Cryptosystems (Symmetric Algorithms): Enigma -- One-time pad -- Data Encryption Standard (DES) -- RC4--Blowfish -- International Data Encryption Algorithm (IDEA) -- Advanced Encryption Standard
- Terminology: /Key -- Cipher -- Code
Further Reading:
- Schneier, Bruce - Applied Cryptography ISBN 0471117099 (amazon.com, search)
- Schneier, Bruce - Secrets and Lies ISBN 0471253111 (amazon.com, search)
- Bamford, James - The Puzzle Palace : A Report on America's Most Secret Agency ISBN 0140067485 (amazon.com, search)
- A. J. Menezes, P. C. van Oorschot and S. A. Vanstone - Handbook of Applied Cryptography ISBN 0849385237 (amazon.com, search) ([online version])
- Kahn, David - The Codebreakers ISBN 0684831309 (amazon.com, search)
Related topics:
Echelon, Enigma, Ultra, Security engineering, Steganography, Cryptographers
/Talk