Encrypting only Passwords in web.config ASP.NET - asp.net

Question

How can I encrypt only passwords in a web.config file?
<add name="PSystem" connectionString="Server=test;Database=Dev;User ID=testuser;Password=password#123;Trusted_Connection=False;Encrypt=True;" providerName="System.Data.SqlClient" />

Answer 1

I believe that built-in encryption mechanisms work on the entire connectionString section:
See this website for more info
If you would like to encrypt in-memory passwords, maybe entered by the user through a login form, you could use SecureString

Answer 2

you can try using flags in the connecction string as follows:
<add name="PSystem"
connectionString="Server=test;
Database=Dev;
User ID=#UserID#;
Password=#Password#;
Trusted_Connection=False;
Encrypt=True;"
providerName="System.Data.SqlClient" />
then you can have the encrypted user and password as follows:
<add key="DB_User" value = [Encrypted Username]>
<add key="DB_Password" value = [Encrypted Password]>
Then in code you just replace the flags:
string _connectionString = ConfigurationManager.ConnectionStrings["PSystem"].ConnectionString;
string user = Decrypt(ConfigurationManager.AppSettings["DB_User"]);
string password = Decrypt(ConfigurationManager.AppSettings["DB_Password"]);
_connectionString = _connectionString.Replace("##User##", user).Replace("##Password##", password);

Answer 3

To encrypt configuration file
contents, use the Aspnet_regiis.exe tool with the –pe option and the
name of the configuration element to be encrypted.
aspnet_regiis -pe "connectionStrings" -app "/SampleApplication" -prov
"RsaProtectedConfigurationProvider"
Source: http://msdn.microsoft.com/en-us/library/zhhddkxy(v=vs.100).aspx