StrongNameKeyManager.cs

using System;
using System.IO;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;

namespace CryptoPlayground.StrongNameKeyManagement
{
    public class StrongNameKeyManager
    {
        public StrongNameKeyManager(string containerName, bool machineScope = true)
        {
            if (containerName == null)
                throw new ArgumentNullException("containerName");

            _containerName = containerName;
            _machineScope = machineScope;
        }

        public StrongNameKeyManager CreateKeyContainer(KeySize keySize = KeySize.L1024)
        {
            var cspParameters = GetCspParametres(_containerName, _machineScope);
            var csp = new RSACryptoServiceProvider((int)keySize, cspParameters)
            {
                PersistKeyInCsp = true
            };

            return this;
        }

        public byte[] ExportPublicKeyFromContainer()
        {
            var cspParameters = GetCspParametres(_containerName, _machineScope);
            var csp = new RSACryptoServiceProvider(cspParameters)
            {
                PersistKeyInCsp = true
            };

            return csp.ExportCspBlob(false);
        }

        public StrongNameKeyManager DeleteKeyContainer()
        {
            var cspParameters = GetCspParametres(_containerName, _machineScope);
            var csp = new RSACryptoServiceProvider(cspParameters)
            {
                PersistKeyInCsp = false
            };

            csp.Clear();

            return this;
        }

        public StrongNameKeyManager ImportKeyStrongNameKeyFile(string fileName)
        {
            var cspParameters = GetCspParametres(_containerName, _machineScope);
            var csp = new RSACryptoServiceProvider(cspParameters)
            {
                PersistKeyInCsp = true
            };

            var fileContent = File.ReadAllBytes(fileName);
            csp.ImportCspBlob(fileContent);

            return this;
        }

        public StrongNameKeyManager ImportFromPersonalInformationExchangeFile(string fileName, string password)
        {
            var cspParameters = GetCspParametres(_containerName, _machineScope);
            var csp = new RSACryptoServiceProvider(cspParameters)
            {
                PersistKeyInCsp = true
            };

            var fileContent = GetStrongNameKeyPairFromPfx(fileName, password);
            csp.ImportCspBlob(fileContent);

            return this;
        }

        private CspParameters GetCspParametres(string containerName, bool machineScope)
        {
            var cspParametres = new CspParameters
            {
                KeyContainerName = containerName,
                KeyNumber = (int)KeyNumber.Signature,
                Flags = CspProviderFlags.UseNonExportableKey
            };

            if (machineScope)
                cspParametres.Flags |= CspProviderFlags.UseMachineKeyStore;
            return cspParametres;
        }

        private byte[] GetStrongNameKeyPairFromPfx(string pfxFile, string password)
        {
            var certs = new X509Certificate2Collection();
            certs.Import(pfxFile, password, X509KeyStorageFlags.Exportable);

            if (certs.Count == 0)
                throw new ArgumentException(null, "pfxFile");

            var provider = certs[0].PrivateKey as RSACryptoServiceProvider;

            if (provider == null) // not a good pfx file
                throw new ArgumentException(null, "pfxFile");

            return provider.ExportCspBlob(true);
        }

        private readonly string _containerName;
        private readonly bool _machineScope;
    }
}