How to display the encrypted connection String of the web.config file in C#?

Question

In my .net web application I encrypted the of the web.config file.

But now I need to read this encrypted connection String from an external winforms application and display the result in a text box . The text box text would look something like this :

 <connectionStrings configProtectionProvider="CustomEncryptProvider">
        <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Element"
            xmlns="http://www.w3.org/2001/04/xmlenc#">
            <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc" />
            <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
                <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">
                    <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5" />
                    <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
                        <KeyName>Rsa Key</KeyName>
                    </KeyInfo>
                    <CipherData>
                        <CipherValue>Smbfcf3dHbuYZ34hLWtATU8fBqNL/CvPk24tLj9gLOizLzV88den52yhtYQ5AwXe2vVZP/GKRsWB+rcX/6ufBkz75HyVOnJHTCgLQ+JcsRX/9Td5ZzWJrEq1JBdpFzBsS9aLGLMREIILPedmFxO5+0GLIaBPzZ9/BhNcN8GXa+k=</CipherValue>
                    </CipherData>
                </EncryptedKey>
            </KeyInfo>
            <CipherData>
                <CipherValue>raoQqDzlXmMCy+3VliV6oyMoQzgIapSmBKw666WbUjLgurCh4aS+pwSMW3wULOpi+jh8BdDE/aPwvhDw9kTuComyHBsEB4xMtRFaBY1NSyrwx7dnP44x4NS+LowJ1EQiN2fAZqWDDVAljRIlq3DtZhC9YkYl4H1rEjQVvljD0pus1O8ftiqKy/yma1/rqzI+F/87GrFR1ZM8cS/ujXagtfzqME4iVdTgl/eyEPkrd5f6SGwlieeC0zJ2ErV9zIr+Af2Sc6mk2hz7/+t2x3kAzDzHU2PFfBqiLSP6o/0XAdRl43Q/Jwr72552mus7n5urlzvyND0KXKzk4Gg4bVYuo8sSQvphbFuLgHIxq+6ShDdCc9wfMzsBmGU4ayYbn/a4rI8lB5y6GzK0kQvnH0qtWQ==</CipherValue>
            </CipherData>
        </EncryptedData>
    </connectionStrings>

How to achieve the same ? Please note I only have the physical path to the web.config file .

Answer 1

You can load a config file using System.Configuration.ConfigurationManager like this:

var config = ConfigurationManager.OpenExeConfiguration(/* path to config file */);

The connection strings will automatically be decrypted, and will be available in the ConnectionStrings property of the Configuration object. In your case, the connection string is called "LocalSqlServer":

Console.WriteLine(config.ConnectionStrings.ConnectionStrings["LocalSqlServer"]);

> data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true

EDIT

If, as you've indicated, you actually want the whole content of the connectionStrings xml element, you can do this with an XmlReader :

using (var reader = XmlReader.Create(/* path to config file */))
{
    if (reader.ReadToDescendant("connectionStrings"))
        Console.WriteLine(reader.ReadOuterXml());
}

> <connectionStrings configProtectionProvider="CustomEncryptProvider">
        <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Element" etc...