using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Security.Cryptography.X509Certificates;
using System.Collections.Generic;

namespace X509Cert
{
    public class PKCS12
    {
        public static X509Certificate2[] Read(string filename, string password)
        {

            FileStream stream = new FileStream(filename, FileMode.Open);
            byte[] buffer = new byte[stream.Length];
            stream.Read(buffer, 0, buffer.Length);
            stream.Close();


            WIN32.CRYPT_DATA_BLOB cryptdata = new WIN32.CRYPT_DATA_BLOB();
            cryptdata.cbData = buffer.Length;
            cryptdata.pbData = Marshal.AllocHGlobal(cryptdata.cbData);
            Marshal.Copy(buffer, 0, cryptdata.pbData, buffer.Length);
            IntPtr hMemStore = WIN32.PFXImportCertStore(ref cryptdata, password, WIN32.CRYPT_USER_KEYSET);
            Marshal.FreeHGlobal(cryptdata.pbData);

            uint provinfosize = 0;

            List<X509Certificate2> certs = new List<X509Certificate2>();

            IntPtr certHandle = IntPtr.Zero;
            while ((certHandle = WIN32.CertEnumCertificatesInStore(hMemStore, certHandle)) != IntPtr.Zero)
            {

                if (WIN32.CertGetCertificateContextProperty(certHandle, WIN32.CERT_KEY_PROV_INFO_PROP_ID, IntPtr.Zero, ref provinfosize))
                {

                    IntPtr info = Marshal.AllocHGlobal((int)provinfosize);

                    if (WIN32.CertGetCertificateContextProperty(certHandle, WIN32.CERT_KEY_PROV_INFO_PROP_ID, info, ref provinfosize))
                    {
                        var certData = new X509Certificate2(certHandle).Export(X509ContentType.SerializedCert);
                        certs.Add(new X509Certificate2(certData));
                    }
                    Marshal.FreeHGlobal(info);

                }
            }

            Marshal.FreeHGlobal(hMemStore);
            return certs.ToArray();

        }
    }
}