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Verifying an encrypted password against a shadow password file

I'm doing a project named Webmail (with Linux/Perl as backend). When a user registers on our site by giving a username...

and password, his password is encrypted and stored in the shadow password file (/etc/shadow). I want to check the password entered by a user with this shadow password file where his password is encrypted through my program. Can you tell me how I can do this?

The routines you need are in . You can find them on a Linux system with "man shadow."

I think the main routine you want is getspent(). This gets the shadow password entry and lets you compare things as you desire. Read through that man page -- it includes the data structures in all their gory detail.

For more information on this topic, visit these other SearchSecurity resources:
Best Web Links: Passwords/Authentication
Ask the Expert: What is password shadowing?
Best Web Links: Securing Linux

This was last published in April 2002

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