The primary objective of using cryptography is to provide the following four fundamental information security services. Let us now see the possible goals intended to be fulfilled by cryptography.
Confidentiality is the fundamental security service provided by cryptography. It is a security service that keeps the information from an unauthorized person. It is sometimes referred to as privacy or secrecy.
Confidentiality can be achieved through numerous means starting from physical securing to the use of mathematical algorithms for data encryption.
It is security service that deals with identifying any alteration to the data. The data may get modified by an unauthorized entity intentionally or accidently. Integrity service confirms that whether data is intact or not since it was last created, transmitted, or stored by an authorized user.
Data integrity cannot prevent the alteration of data, but provides a means for detecting whether data has been manipulated in an unauthorized manner.
Authentication provides the identification of the originator. It confirms to the receiver that the data received has been sent only by an identified and verified sender.
Authentication service has two variants −
- Message authentication identifies the originator of the message without any regard router or system that has sent the message.
- Entity authentication is assurance that data has been received from a specific entity, say a particular website.
Apart from the originator, authentication may also provide assurance about other parameters related to data such as the date and time of creation/transmission.
It is a security service that ensures that an entity cannot refuse the ownership of a previous commitment or an action. It is an assurance that the original creator of the data cannot deny the creation or transmission of the said data to a recipient or third party.
Non-repudiation is a property that is most desirable in situations where there are chances of a dispute over the exchange of data. For example, once an order is placed electronically, a purchaser cannot deny the purchase order, if non-repudiation service was enabled in this transaction.