Re: Reversal encryption

"David Ching" <>
Tue, 25 Nov 2008 07:23:31 -0800
"Jeova Almeida" <> wrote in message


I need a good algorithm for encrypting some vital information about my app
in an INI file. I have a class for MD5, but it's not reversible.

I'd like to use a private or public key to decrypt the text. By the way,
what's the difference between private and public key when we talk about

Sugestions, please?

Yes, you can use the Crypto API to encrypt your text. The Crypto API offers
many algorithms, both public and private encryption, but make sure that the
one you choose is supported on all versions of Windows that you need to work
with. For example, I think SHA-256 is only supported on Windows 2003 Server
and later.

I believe you are best served with a symmetric key algorithm and not public
key encryption. Symmetric key algorithms use the same key to encrypt and
decrypt the text. Public key encryption has 2 keys, the public key and
private key. The text is encrypted with one of these keys, and decrypted
with the other key (the first key cannot be used to decrypt, you must use
the second key!). But you don't need 2 keys, because both keys would be
stored in your app, and if the hacker got the first key, they could easily
get the second key. So having 2 keys is not anymore secure, and the public
key algorithms are orders of magnitude slower to execute than symmetric
algorithms. The only time public key encryption is useful is if you can
physically separate the 2 keys, like storing one of the keys on a web
server, and the other key on the client.

-- David

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