The sender can then transmit this package to the receiver, who can look at the package, see what algorithm was used for the one-way hash and quickly compute the hash. Then the receiver can decrypt the received encrypted one-way hash and compare it with the hash that was just computed. If the two hashes match, the receiver knows exactly who sent the message and knows that the message was transmitted without modification. Sometimes, you need to know that the conversation is completely private. Although the data integrity feature is optional, if one is using data confidentiality, it is usually done as the cost of computing, and encrypting the one-way hash is minor compared to the cost of encrypting the whole message.
Encryption is a costly operation, both in terms of processing power and time.
If it were not, then data confidentiality would always be used. But it is, so it is important to allow applications to pick the level of protection that they need at the point where it is needed, and Kerberos provides this. We have described only the high-level mechanics of Kerberos. One may wonder how hackers might attack a Kerberos-secured network and what some of its vulnerabilities might be. The only entrance into the Kerberos protocol is where a user specifies a password to start the process.