code: public void setCrypto(PrivateKey privKey, Certificate[] certChain, CRL[] crlList, PdfName filter) {
          this.privKey = privKey;
          this.certChain = certChain;
          this.crlList = crlList;
          this.filter = filter;
      }
docs: Sets the cryptographic parameters.
  @param privKey the private key
  @param certChain the certificate chain
  @param crlList the certificate revocation list. It may be <CODE>null</CODE>
  @param filter the crytographic filter type. It can be SELF_SIGNED, VERISIGN_SIGNED or WINCER_SIGNED