iTextSharp.text.pdf.PdfPublicKeySecurityHandler.ComputeRecipientInfo C# (CSharp) Метод

        private KeyTransRecipientInfo ComputeRecipientInfo(X509Certificate x509certificate, byte[] abyte0)
        {
            Asn1InputStream asn1inputstream =
                new Asn1InputStream(new MemoryStream(x509certificate.GetTbsCertificate()));
            TbsCertificateStructure tbscertificatestructure =
                TbsCertificateStructure.GetInstance(asn1inputstream.ReadObject());
            AlgorithmIdentifier algorithmidentifier = tbscertificatestructure.SubjectPublicKeyInfo.AlgorithmID;
            Org.BouncyCastle.Asn1.Cms.IssuerAndSerialNumber issuerandserialnumber =
                new Org.BouncyCastle.Asn1.Cms.IssuerAndSerialNumber(
                    tbscertificatestructure.Issuer,
                    tbscertificatestructure.SerialNumber.Value);
            IBufferedCipher cipher = CipherUtilities.GetCipher(algorithmidentifier.ObjectID);
            cipher.Init(true, x509certificate.GetPublicKey());
            byte[] outp = new byte[10000];
            int len = cipher.DoFinal(abyte0, outp, 0);
            byte[] abyte1 = new byte[len];
            System.Array.Copy(outp, 0, abyte1, 0, len);
            DerOctetString deroctetstring = new DerOctetString(abyte1);
            RecipientIdentifier recipId = new RecipientIdentifier(issuerandserialnumber);
            return new KeyTransRecipientInfo( recipId, algorithmidentifier, deroctetstring);
        }