"CSP for this implementation could not be acquired" CryptographicException error during instantiation (322371)

RESOLUTION

.NET Framework 1.1 and later versions

If the .NET Framework-based application is intended for use together with the .NET Framework 1.1 or a later version, you can use the feature that is documented at the following Microsoft Developer Network Web site to instruct RSACryptoServiceProvider to use the machine key store: In this method, you use the static property as follows:

RSACryptoServiceProvider.UseMachineKeyStore = true;

The UseMachineKeyStore static property applies to all code in the current application domain.

.NET Framework 1.0

You must instruct RSACryptoServiceProvider or DSACryptoServiceProvider to use machine key store (as in the following sample code) in scenarios such as a Web service, ASP Page, or COM+, where the user profile is not loaded by the system for performance reasons. You can use the CspParameters parameter in the RSACryptoServiceProvider() constructor, as follows.

CspParameters CSPParam = new CspParameters();
CSPParam.Flags = CspProviderFlags.UseMachineKeyStore;
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(CSPParam);
				

The following C# sample code demonstrates how to use the machine key store when RSACryptoServiceProvider is used indirectly by the SignedXml class while signing an XML file or verifying a signed XML file. This sample code assumes that the XML file was signed by using RSA keys. The sample code signs an input XML file. The signed file is stored in EnvelopingSig.xml, which is then verified.

using System;
using System.Xml;
using System.IO;
using System.Text;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;

namespace XmlSample
{
    public class XmlDigitalSigning
    {
        public enum SigType 
        {
            Detached = 1,
            Enveloping = 2,
            Enveloped = 3
        }
 
        public SignedXml Sign(String Uri, RSACryptoServiceProvider rsa, SigType type)
        {
            // Create the SignedXml message.
            SignedXml xmlSign = new SignedXml();
            // Set the RSA key for signing.
            xmlSign.SigningKey = rsa;

            // Create a Reference to point to the to-be-signed content.
            Reference reference = new Reference();

            if (type == SigType.Detached)
            {
                reference.Uri = Uri;
            }
            else if (type == SigType.Enveloping)
            {
                XmlDocument doc = new XmlDocument();
                DataObject obj = new DataObject();
                doc.Load(Uri);
                obj.Data = doc.ChildNodes;
                obj.Id = "MyObjectId";
                reference.Uri = "#" + "MyObjectId";
                xmlSign.AddObject(obj);
            }

            // Add the Reference to the SignedXml message.
            xmlSign.AddReference(reference);
            // Add a KeyInfo element to the SignedXml message.
            KeyInfo keyInfo = new KeyInfo();
            keyInfo.AddClause(new RSAKeyValue((RSA)rsa));
            xmlSign.KeyInfo = keyInfo;

            // Compute the XML Digital Signature.
            xmlSign.ComputeSignature();
            return xmlSign;
        }

        public bool Verify(String signedxmlFile)
        {
            bool bResult = false;
        
            FileStream inputStream = new FileStream(signedxmlFile, FileMode.Open);
        
            // Load the XML.
            XmlDocument doc = new XmlDocument();
            XmlTextReader xtr = new XmlTextReader(inputStream);
            doc.Load(xtr);

            // Get RSAKeyValue Element from the signed XML.
            SignedXml signedXml = new SignedXml();
            XmlNodeList rsaKeyValueNodes = doc.GetElementsByTagName("RSAKeyValue");
            XmlElement rsaKeyValueElement = (XmlElement) rsaKeyValueNodes.Item(0);
            String rsaKeyValueString = rsaKeyValueElement.OuterXml;

            // Remove the KeyInfo node from the SignedXml signature.
            XmlNodeList KeyInfoNode = doc.GetElementsByTagName("KeyInfo");
            XmlElement keyInfoElement = (XmlElement) KeyInfoNode.Item(0);
            XmlElement signatureElement = (XmlElement) keyInfoElement.ParentNode;
            // Console.WriteLine("****");
            // Console.WriteLine(keyInfoElement.OuterXml);
            // Console.WriteLine("****");
            // Console.WriteLine(signatureElement.OuterXml);
            // Console.WriteLine("****");
            signatureElement.RemoveChild(keyInfoElement);
            // Console.WriteLine(doc.DocumentElement.OuterXml);
            // Console.WriteLine("****");

            // Use machine key store.
            CspParameters cspParams = new CspParameters();
            cspParams.Flags = CspProviderFlags.UseMachineKeyStore;
            RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(cspParams);
            rsaKey.FromXmlString(rsaKeyValueString);

            // Set the keyInfo.
            KeyInfo keyInfo = new KeyInfo();
            keyInfo.AddClause(new RSAKeyValue(rsaKey));
            signedXml.KeyInfo = keyInfo;

            // Load the signature.
            signedXml.LoadXml(doc.DocumentElement);

            AsymmetricAlgorithm key;
            if (signedXml.CheckSignatureReturningKey(out key)) 
            {
                bResult = true;
            } 
            else 
            {
                bResult = false;
            }
        
            return bResult;
        }
    }
    class XmlSampleCode
    {
        static void Main(string[] args)
        {
            int nArgs;

            // args[1] - XML file to be signed
            nArgs = args.Length;
            if (nArgs < 1)
            {
                Environment.Exit(-1);
            }
            for (int i = 0; i < nArgs; i++)
            {
                Console.WriteLine("Args[{0}] = {1}", i, args[i]);
            }
            try
            {
               CspParameters cspParams = new CspParameters();
               cspParams.Flags = CspProviderFlags.UseMachineKeyStore;
               RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(cspParams);

                XmlDocument xmlOutput = new XmlDocument();
                XmlDigitalSigning digSign = new XmlDigitalSigning();
                SignedXml xmlSign;

                xmlSign = digSign.Sign(args[0], rsa, XmlDigitalSigning.SigType.Enveloping);
                XmlTextWriter xmltw = new XmlTextWriter("EnvelopingSig.xml", new UTF8Encoding(false));
                xmltw.Formatting = Formatting.Indented;
                xmlOutput.InnerXml = xmlSign.GetXml().OuterXml;
                xmlOutput.WriteTo(xmltw);
                xmltw.Flush();
                xmltw.Close();

                if (digSign.Verify("EnvelopingSig.xml"))
                {
                    Console.WriteLine("Signature has been verified successfully");
                }
                else
                {
                    Console.WriteLine("Signature verification failed");
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("\nException Information : \n\n{0}", e.ToString());
            }
            return;
        }
    }
}