asp.net - Encrypt Connection String in Web.Config Fails -

i encrypt connection string of web.config. here have found nice example on how this. implemented , on development machine runs find. if upload provider, not work following error:

[securityexception: request failed.] system.configuration.dpapiprotectedconfigurationprovider.encrypt(xmlnode node)

in this blog have read, because of web runs in medium trust , therefore webconfigurationmanager.openwebconfiguration can not used. instead of this, webconfigurationmanager.getsection should used. however, if section proposed, call protectsection fails following error message:

system.invalidoperationexception: operation not apply @ runtime

can lead me solution, how can encode (and decode) connection string in web.config file (at runtime)?

update
not real answer question, hoster gave full trust web , now, worked fine. leave quesion open, maybe posts solution original question , helps people having same problem not getting full trust.

from http://msdn.microsoft.com/en-us/library/89211k9b%28v=vs.80%29.aspx

static void togglewebencrypt() {     // open web.config file.     configuration config = webconfigurationmanager.         openwebconfiguration("~");      // connectionstrings section.     connectionstringssection section =         config.getsection("connectionstrings")         connectionstringssection;      // toggle encryption.     if (section.sectioninformation.isprotected)     {         section.sectioninformation.unprotectsection();     }     else     {         section.sectioninformation.protectsection(             "dataprotectionconfigurationprovider");     }      // save changes web.config file.     config.save(); } 

update

also, ensure service account has write permissions web.config. also, aware granting write permissions service account on web.config increases security footprint of application. if understand , accept risks.