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Asked: 2026-06-12T11:13:11+00:00

Unfortunately, I have some code that does this: byte[] plainText = System.Text.Encoding.ASCII.GetBytes(ClearText); var btcipherText

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Unfortunately, I have some code that does this:

            byte[] plainText = System.Text.Encoding.ASCII.GetBytes(ClearText);
            var btcipherText = enc.Encrypt(plainText, btkey);
            System.Text.Encoding en = System.Text.Encoding.Default;
            return en.GetString(btcipherText);

Which is then saved to the database as a user’s password.

In mono, on Ubuntu 12.04, System.Text.Encoding.Default is System.Text.Encoding.UTF8, while on Windows 7, it seems to be System.Text.SBCSCodePageEncoding.

The password encryption/decryption code should never have been using System.Text.Encoding.Default, but this is inherited code. Looking in System.Text.Encoding, and having googled my problem extensively, I am unable to determine how I might decode this string with a standard encoding, and in this case on a Mono/Linux stack that lacks the original encoding.

I’ve also strangely not been able to find much information on System.Text.SBCSCodePageEncoding

When I try to decrypt a string stored with this encoding, I get the usual “Bad data” and “Invalid block size” Cryptographic exceptions.

Any information or suggestions are appreciated.

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1 Answer

  1. Editorial Team

    Building on the other answer, given that you know which limited set of encodings are used to convert the byte[] to a string, build a utility (or build it into the app so that passwords are upgraded as they are used) that read and decodes the password back to a valid byte[] then store the byte[] as Base64 in the database.

    I see your also considering hashing the passwords, in this case and almost any other case if your dealing with a byte[] that doesn’t actually represent text, that you need to store/display as characters then base64 is always a good option.

    If you decide to hash the passwords make sure you use a HMAC style hashing system rather than just a plain password + salt, or even better grab a bcrypt implementation for .net.

    http://derekslager.com/blog/posts/2007/10/bcrypt-dotnet-strong-password-hashing-for-dotnet-and-mono.ashx

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