Leveraging ASP.NET machineKey For Encrypting My Own Data

Question

I have some data I want to encrypt in an ASP.NET MVC application to prevent users from tampering with it. I can use the Cryptography classes to do the actual encryption/decrypt

Answer 1

The new MachineKey class in ASP.NET 4.0 does exactly what you want.

For example:

public static class StringEncryptor {
    public static string Encrypt(string plaintextValue) {
        var plaintextBytes = Encoding.UTF8.GetBytes(plaintextValue);
        return MachineKey.Encode(plaintextBytes, MachineKeyProtection.All);
    }

    public static string Decrypt(string encryptedValue) {
        try {
            var decryptedBytes = MachineKey.Decode(encryptedValue, MachineKeyProtection.All);
            return Encoding.UTF8.GetString(decryptedBytes);
        }
        catch {
            return null;
        }
    }
}

UPDATE: As mentioned here, be careful how you use this or you could allow someone to forge a forms authentication token.