encrypting files in a script

[Hasnain Mujtaba]

Hi,

I am encrypting some files using a shell script. GPG asks the question: 

"It is NOT certain that the key belongs to the person named
in the user ID.  If you *really* know what you are doing,
you may answer the next question with yes"

How can I supress this question so the script can run through the end?

Thanks
Hasnain.

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