Key difference: both version 4 of Kerberos and version 5 are updates of the Kerberos software. Kerberos v4 is the predecessor of Kerberos v5.
Kerberos is a web-based software that is used to provide authentication to user identities and user requests. The Internet can be a very insecure place. It often involves the exchange of sensitive information related to users, such as their user names, passwords, financial details, etc. Such information once exchanged may be subject to a wide range of scrutiny by hackers and criminals. On occasion, a website may experience heavy user traffic. In such a scenario, it is easy for hackers and other criminals to detect the details of the users and use them to their advantage (of the hackers).
To eliminate that annoyance, the Kerberos software was developed. The word 'Kerberos' is derived from Greek mythology, where it represents the name of the three-headed dog that guarded the gates of Hades. Kerberos was developed for the first time and put into use at the Massachusetts Institute of Technology (MIT). The first three versions of this software operated within the MIT campus itself. It was not until the late 1980s that Kerberos was available to the masses and the Internet through the release of its software version 4. Mainly developed for MIT's own Athena Project, Kerberos was designed primarily by Steve Miller and Clifford Neuman.
The operation of Kerberos is based on the authentication server (AS). This type of server is essential to provide users with 'tickets', which validate their requests. For example, if a user requests a payment service, the authentication server will automatically generate a session key and a particular ID, with which the user enters their data and obtains the service. This is where Kerberos enters the scene. These passwords and other information are in an exposed form on the cable. With the help of Kerberos software, vital data like this is encrypted and protected regularly at each stage of the transaction.
After publishing the version 4 in the marginalized one of the decade of 1980, Clifford Neuman collaborated with John Kohl to present the version 5 of Kerberos, that was an update of the version 4 of Kerberos. Version 4 had experienced many limitations and security issues due to the advancement of technology around it. As a result, version 4 became obsolete and had to be replaced by RFC 1510, or version 5 of Kerberos, in the year 1993.