Don't.
Hash it instead. Look at the System.Cryptography namespace, and use SHA hashing to generate a value to store in you database. When you need to check it, hash whatever the user gave you, and compare the hashes. If they are the same, the user can be logged in. If not, he can't.
It is also a good idea to include the username or Id in the data before you hash it, so that two users with the same password do not generate the same hash value.
If you use encryption, you need a key in your code which decrypts it - this posses a big security risk. Hashing does not need a key because it is one-way.
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I have written up a description of this with appropriate code as a Tip / Trick:
Password Storage: How to do it.[
^]
It should be available soon, depending on how quickly article moderation is going today!
OriginalGriff
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