[brokenmachine]

It's trivially easy to create a malicious file with the same CRC as another file.

So "verifying" using CRC is very stupid if you're trying to prevent malicious execution. You need to use cryptographic signatures.

[AlotOfReading]

The entire point of my post was that it's trivial, exactly as difficult as computing the CRC in the first place. Not sure why that was controversial.

Nevertheless, they're still useful protection against noise, and you usually want to detect it right as you're pulling protocol messages off the wire. Placing checksums in the last field of each message (as Ethernet does) simplifies the hardware implementation.