Encrypt and Decrypt configuration files using Code

How to encrypt connection string in asp.net stored in web.config.
Using System.web.configuration;
Protected void button_click(object sender,eventargs e)
{
string webconfigpath="~";
configuration config=webconfigurationmanager.openwebconfiguration(webconfigpath);
configurationsection configsection=config.Getsection("connectionstrings");
configsection.sectionInformation.protectsection("Dataprotectionconfigurationprovider");
config.save();
}

How to decrypt connection string in asp.net stored in web.config.
Using System.web.configuration;
Protected void button_click(object sender,eventargs e)
{
string webconfigpath="~";
configuration config=webconfigurationmanager.openwebconfiguration(webconfigpath);
configurationsection configsection=config.Getsection("connectionstrings");
configsection.sectionInformation.Unprotectsection();
config.save();
}