RSACryptoServiceProvider CryptographicException System Cannot Find the File Specified under ASP.NET

.net, application-pool, asp.net, cryptography

Solution

Indeed you need to work a code like this

CspParameters _cpsParameter;
RSACryptoServiceProvider RSAProvider;

_cpsParameter = new CspParameters();
_cpsParameter.Flags = CspProviderFlags.UseMachineKeyStore;

RSAProvider = new RSACryptoServiceProvider(1024, _cpsParameter);

The following users need access to the folder: C:\Documents and Settings\All Users\Application data\Microsoft\Crypto\RSA\MachineKeys

- IIS user account (anonymmous)

- The user account you use to impersonate your application in the web.config settings.

So now it is working fine for me.

Problem

I have an application which is making use of the RSACryptoServiceProvider to decrypt some data using a known private key (stored in a variable). When the IIS Application Pool is configured to use Network Service, everything runs fine. However, when we configure the IIS Application Pool to run the code under a different Identity, we get the following: ``` System.Security.Cryptography.CryptographicException: The system cannot find the file specified. at System.Security.Cryptography.Utils.CreateProvHandle(CspParameters parameters, Boolean randomKeyContainer) at System.Security.Cryptography.RSACryptoServiceProvider.ImportParameters(RSAParameters parameters) at System.Security.Cryptography.RSA.FromXmlString(String xmlString) ``` The code is something like this: ``` byte[] input; byte[] output; string private_key_xml; var provider = new System.Cryptography.RSACryptoServiceProvider(this.m_key.Key_Size); provider.FromXmlString(private_key_xml); // Fails Here when Application Pool Identity != Network Service ouput = provider.Decrypt(input, false); // False = Use PKCS#1 v1.5 Padding ``` There are resources which attempt to answer it by stating that you should give the user read access to the machine key store - however there is no definitive answer to solve this issue. Environment: IIS 6.0, Windows Server 2003 R2, .NET 3.5 SP1

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