Cryptography, in general is the science and art to maintain the confidentiality of news [Bruce Schneier - Applied Cryptography]. Besides these terms there is also understanding the study of mathematical techniques related to aspects of information security such as confidentiality of data, the validity of data, data integrity, and authentication data [A. Menezes, P. van Oorschot and S. Vanstone - Handbook of Applied Cryptography]. Not all aspects of information security are handled by cryptography.
There are four fundamental goals of cryptography is the science which is also the aspect of information security:
* Confidentiality is a service that is used to keep the contents of the information from anyone except those with authority or a secret key to open / peel information that has been encoded.
* Integrity of data, is associated with preservation of the change in illegal data. To maintain the integrity of data, the system must have the ability to detect data manipulation by the parties who are not entitled, including insertion, deletion, and other data pensubsitusian into the actual data.
* Authentication, is associated with the identification / recognition, either in whole systems and information itself. The two parties must communicate with each other to introduce themselves to each other. The information sent through the channel must be authenticated origin, data content, delivery time, and others.
* Non-repudiasi., Or nirpenyangkalan is an attempt to prevent the denial of the transfer / creation of an information by the sending / making.