What is Symmetric Key Authentication in information security?

A symmetric key is one that can be used both to encrypt and decrypt data. This means that to decrypt data, one should have the similar key that was used to encrypt it. Symmetric encryption is usually more effective than asymmetric encryption and therefore preferred when high amounts of data need to be exchanged.

It can be creating the shared key is complex using only symmetric encryption algorithms, so in some cases, an asymmetric encryption is used to create the shared key between two parties.

The Digital Encryption Standard (DES) algorithm is a symmetric key cryptography approach commonly used smart card systems. This approach need a stored, secret cryptographic key and the public DES algorithm in each smart card and CAD. There are various steps in symmetric key authentication are as follows −

  • The smart card sends the microprocessor serial number (I) to the CAD, which connect the number with the master key (Mk) to form the smart card's diversified key (K). The issuer loads a diversified key into every smart card during card initialization.

  • The CAD makes a random number (R), thus encrypts R to form the value Y that is sent as the challenge to the smart card.

  • The smart card decrypts Y, forming the response (X) and restore X to the CAD.

  • The CAD compares R and X, accepting the card if the two values connect.

The Telepass 1 algorithm is an algorithm used for smart card authentication. This algorithm needs a diversified secret key, the contents of a definite word in the smart card memory, and a random outside value to compute the response to an authentication challenge. The Telepass 1 algorithm supports functionality for data secrecy in key distribution and data integrity through message authentication codes.

In a symmetric key system, the secret key in each smart card should be unique so that discovery of the key does not negotiate the whole system. This key diversification supports a unique cryptographic key for each smart card during personalization. The system develop the diversified key from the set of a system master key and a unique card characteristic including the microprocessor serial number.

The CAD include a copy of the master key so they can manufacture the changed key for each smart card. Compromise of a diversified key has small effect on the system, supported the compromise is find and the card can be eliminated from the system. The compromise of a master key can have serious result.

The compromise of a master key needed that all cards should be loaded with new keys, which is costly to the systems and cumbersome for users. It can avoid key compromise, the CAD can include a security module with secured memory (i.e., smart card), where the master key is stored.