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Effective Password Encryption

Asked 2009-05-19T15:13:43.210
12

I've taken a look at the StackOverflow question, "Password Encryption / Database Layer AES or App Layer AES," and I'd like to effectively and efficiently hash my passwords on registration (web app) and then be able to check they are correct on login. I'm using VB, but comfortable using C#.

I would love to use Jeff Atwood's Encryption class described in ".NET Encryption Simplified" as it's really easy to understand. It has a hashing class—but I have no idea how to "login" and compare hashes after they have been hashed. This is Jeff's demonstration of his hash methods using his Encryption class:

Sub DemoHash()
    Dim d As New Encryption.Data( _
        "{ts '2004-10-09 08:10:04'}The world is beautiful and needs caring by its children")

    Dim hash As New Encryption.Hash(Encryption.Hash.Provider.SHA1)
    Dim hash2 As New Encryption.Hash(Encryption.Hash.Provider.SHA256)
    Dim hash3 As New Encryption.Hash(Encryption.Hash.Provider.SHA384)
    Dim hash4 As New Encryption.Hash(Encryption.Hash.Provider.SHA512)
    Dim hash5 As New Encryption.Hash(Encryption.Hash.Provider.MD5)
    Dim hash6 As New Encryption.Hash(Encryption.Hash.Provider.CRC32)

    hash.Calculate(d)
    hash2.Calculate(d)
    hash3.Calculate(d)
    hash4.Calculate(d)
    hash5.Calculate(d)

    Console.WriteLine("SHA1:   " & hash.Value.Hex)
    Console.WriteLine("SHA256: " & hash2.Value.Hex)
    Console.WriteLine("SHA384: " & hash3.Value.Hex)
    Console.WriteLine("SHA512: " & hash4.Value.Hex)
    Console.WriteLine("MD5:    " & hash5.Value.Hex)
    Console.WriteLine("CRC32:  " & hash6.Calculate(d).Hex)
    Console.WriteLine()

    Dim salt As New Encryption.Data("salty!")
    Console.WriteL
asp.net security encryption hash
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1 Answer

4

Don't confuse encrypting passwords with hashing them; with a good cryptographic hash function, you should not be able to reverse the hashing process to retrieve the original string.

Chad's answer above is an excellent point-by-point explanation of the concepts involved.

This subject's been done to death all over the Internet; not just on Stack Overflow; seriously - a simple web search ought to find you a pretty comprehensive guide.

Thanks, Jeff, for spreading yet another bunch of misinformation. I suppose we'll see a whole slew of misguided questions about hashing, encryption, etc. over the next week, not to mention the crap that'll come up about floating-point arithmetic.

answered 2009-05-19T15:18:25.433

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