[ASKED] authentication of User in ASP Using File Password

Hei All Master and Shuhu Of ASP and ASP.Net !!
:)
i need help to solve my problem about authentication
i have a website and a form of login for user. now, i want change the 'password' (that use a word like 'h3lpm3Ple4s3') become 'the files password' (i mean use a file like *.key or another extension file) on asp or asp.net frameworks.
Thanx before 4 ur help

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