Data Security Definition Security is defined as "a guarantee that an obligation will be met". In simplest form it is concerned with people trying to access remote services that they are not authorized to use or it is concerned with making sure that nosy people cannot read, or worse yet, modify messages intended for other recipients. Security is a broad topic and covers a multitude of sins. Most security problems intentionally caused by malicious people trying to gain some benefit or harm someone. A few of the most common perpetrators are student, hacker, sales representative, business man, ex-employee, accountant, stock broker, conman, spy, etc. The intruders would first have a panoramic view of the victim's network and then start digging the holes. Today the illicit activities of the hackers are growing by leaps and bounds. Data security problems can be divided roughly into four intertwined areas: Secrecy, Authentication, NonRepudiation and Integrity control. The solutions for various type of security attacks are provided by cryptography, firewalls etc. a) Secrecy - has to do with keeping information out of the hands of unauthorized users. b) Authentication- deals with determining whom you are talking to before revealing sensitive information or entering into a business deal. c) Non repudiation- deals with signatures d) Data integrity- Ensures that the information exchanged in an electronic transaction is not alterable without detection, typically provided by digital signatures.