Best and worst interview questions

[Old Hack]

Worst:
What is the prime meridian

Best:
How come you've moved jobs so often.....

[fullyautomatix]

Worst:
List me all the differences between all the version of .NET framework.

[DimPrawn]

Easy one.

You need to check that a remote system has the correct credit card number for a customer you hold data on.

However, you cannot query this remote system directly, you must submit the query to another system, which in turn will query the credit card system. You don't want this intermediary system to obtain the credit card number (for security purposes), but you want to verify the credit card number your system holds is the same as the remote system.

How would you implement this?

[fullyautomatix]

Easy one.

You need to check that a remote system has the correct credit card number for a customer you hold data on.

However, you cannot query this remote system directly, you must submit the query to another system, which in turn will query the credit card system. You don't want this intermediary system to obtain the credit card number (for security purposes), but you want to verify the credit card number your system holds is the same as the remote system.

How would you implement this?

Using a shared key, pass an encrypted value.

[DimPrawn]

Using a shared key, pass an encrypted value.

Along those lines, either asymmetric encryption or one way hashing.

[fullyautomatix]

Along those lines, either asymmetric encryption or one way hashing.

I am not sure one way hashing will work in this instance. If the remote system has one way hashed the credit card number, they are not going to share the hash algorithm with you so you can do a similar hash.

[DimPrawn]

I am not sure one way hashing will work in this instance. If the remote system has one way hashed the credit card number, they are not going to share the hash algorithm with you so you can do a similar hash.

If you and the remote system both use the same hash algo (e.g. SHA-512) then the middleware system simply asks for the hash and passes it to you to compare to your hash. The hash cannot realistically be used to recover the CC number, so it is safe for the middle system to have it.

[doodab]

Send a one-time challenge and have the remote system compute a hashed using an algorithm seeded with the CC number. Perform the same computation on your side and compare the two results.

[filthy1980]

call a bob and ask him to read the CC numbers out to you

[d000hg]

What are the best and worst interview questons you can been asked over the years?

Best:

The technical guy is on holiday, so can we cut the interview and have you start tomorrow morning

Worst:

We have this tree structure, right.....

Best: do you know what you're doing?
Worst: can you prove you know what you're doing?

And we wonder why contractors have a reputation as cowboys, based on the lax interviewing techniques being suggested, and the affront caused by actually testing anyone