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Transposition and Hashing - Suppose you have to store employee records for your employer, the largest company in the state of Maryland. The primary key is the Social Security number. You need to primarily access individual records, but occasionally expect to need to print out the file for an employee directory. Identify one other way in which you need to access the data and justify a hashing and collision-handling scheme.

Answer:

The biggest issue I see with using SSNs as key are privacy concerns. Even with hashing, the amount of entropy in the set of valid SSNs is very low. The number of collisions could be high and it wouldn't be too difficult for an attacker to determine the SSN eventually. Like others have said, I think combining a portion of the SSN with another identifier like last name or address. While we could simply use a secure hashing algorithm with very low probability of collision like SHA-256, our hash table would have to be even larger than if we used the SSN directly.

One way we might want to access employee records could be producing performance metrics about a group of employees. For instance, we might want to rank the members of a sales team by their total yearly sales.

Answer 1

The approach used is correct.Combining the SSN with other parameters would make it more secure and difficult to hack.

This also means that the collision probability in the Hash Table can be reduced.

Also it need not be the Entire SSN or the other parameter that we need to consider we can take a portion of the SSN and combine with a Portion of the other parameter that can make the Key Unique and also the size occupied would also be minimal.