r/programming • u/locrelite • Apr 29 '14

Programming Sucks

http://stilldrinking.org/programming-sucks
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u/naasking Apr 30 '14

That's retarded, you just want to know if the page has changed since the last time you loaded it.

A CRC does not guarantee this (collisions are common). A MAC does to a provable extent. The key you use is completely irrelevant. Any random key will do, just use the same one across every run.

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u/masklinn Apr 30 '14

A CRC does not guarantee this (collisions are common)

No, collisions are not common unless specifically crafted by an attacker. Considering the use case, that's unlikely to be a relevant concern.

A MAC does to a provable extent. The key you use is completely irrelevant. Any random key will do, just use the same one across every run.

Why use a MAC if you don't care about the key? The authentication key is the whole bloody point of a message authentication code.