/// <summary>Converts DER binary format to a CAPI CRYPT_PRIVATE_KEY_INFO structure.</summary>
        internal static byte[] GetPrivateKeyDER(byte[] DERData)
        {
            byte[] data = null;
            UInt32 dwRSAPrivateKeyBlobSize = 0;
            IntPtr pRSAPrivateKeyBlob      = IntPtr.Zero;

            if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.PKCS_RSA_PRIVATE_KEY),
                                                                    DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwRSAPrivateKeyBlobSize))
            {
                data = new byte[dwRSAPrivateKeyBlobSize];
                if (!RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.PKCS_RSA_PRIVATE_KEY),
                                                                         DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwRSAPrivateKeyBlobSize))
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            else
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
            return(data);
        }
        /// <summary>Converts DER binary format to a CAPI CERT_PUBLIC_KEY_INFO structure containing an RSA key.</summary>
        internal static byte[] GetRSAFromDER(byte[] DERData)
        {
            byte[] data      = null;
            byte[] publicKey = null;
            CERT_PUBLIC_KEY_INFO info;
            UInt32 dwCertPublicKeyInfoSize = 0;
            IntPtr pCertPublicKeyInfo      = IntPtr.Zero;

            if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.X509_PUBLIC_KEY_INFO),
                                                                    DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwCertPublicKeyInfoSize))
            {
                data = new byte[dwCertPublicKeyInfoSize];
                if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.X509_PUBLIC_KEY_INFO),
                                                                        DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwCertPublicKeyInfoSize))
                {
                    GCHandle handle = GCHandle.Alloc(data, GCHandleType.Pinned);
                    try
                    {
                        info      = (CERT_PUBLIC_KEY_INFO)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(CERT_PUBLIC_KEY_INFO));
                        publicKey = new byte[info.PublicKey.cbData];
                        Marshal.Copy(info.PublicKey.pbData, publicKey, 0, publicKey.Length);
                    }
                    finally
                    {
                        handle.Free();
                    }
                }
                else
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            else
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
            return(publicKey);
        }
        /// <summary>Returns a public key blob from an RSA public key.</summary>
        internal static byte[] GetPublicKeyBlobFromRSA(byte[] RSAData)
        {
            byte[] data = null;
            UInt32 dwCertPublicKeyBlobSize = 0;

            if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING,
                                                                    new IntPtr((int)CRYPT_OUTPUT_TYPES.RSA_CSP_PUBLICKEYBLOB), RSAData, (UInt32)RSAData.Length, CRYPT_DECODE_FLAGS.NONE,
                                                                    data, ref dwCertPublicKeyBlobSize))
            {
                data = new byte[dwCertPublicKeyBlobSize];
                if (!RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING,
                                                                         new IntPtr((int)CRYPT_OUTPUT_TYPES.RSA_CSP_PUBLICKEYBLOB), RSAData, (UInt32)RSAData.Length, CRYPT_DECODE_FLAGS.NONE,
                                                                         data, ref dwCertPublicKeyBlobSize))
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            else
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
            return(data);
        }