/// <summary>
 /// Find public key certificate by system title.
 /// </summary>
 /// <param name="systemTitle">System title.</param>
 /// <returns>Found certificate or null if certificate is not found.</returns>
 public GXx509Certificate FindBySystemTitle(byte[] systemTitle)
 {
     return(FindByCommonName(GXAsn1Converter.SystemTitleToSubject(systemTitle)));
 }