PHP 2-way encryption: I need to store passwords that can be retrieved

Posted by gAMBOOKa on Stack Overflow See other posts from Stack Overflow or by gAMBOOKa
Published on 2011-02-23T10:48:00Z Indexed on 2011/02/25 23:25 UTC
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Filed under:

php

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security

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encryption

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passwords

I am creating an application that will store passwords, which the user can retrieve and see. The passwords are for a hardware device, so checking against hashes are out of the question.

What I need to know is:

How do I encrypt and decrypt a password in PHP?
What is the safest algorithm to encrypt the passwords with?
Where do I store the private key?
Instead of storing the private key, is it a good idea to require users to enter the private key any time they need a password decrypted? (Users of this application can be trusted)
In what ways can the password be stolen and decrypted? What do I need to be aware of?

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