private KeyTransRecipientInfo computeRecipientInfo(X509Certificate x509certificate, byte[] abyte0) throws GeneralSecurityException, IOException { ASN1InputStream asn1inputstream = new ASN1InputStream(new ByteArrayInputStream(x509certificate.getTBSCertificate())); TBSCertificateStructure tbscertificatestructure = TBSCertificateStructure.getInstance(asn1inputstream.readObject()); AlgorithmIdentifier algorithmidentifier = tbscertificatestructure.getSubjectPublicKeyInfo().getAlgorithmId(); IssuerAndSerialNumber issuerandserialnumber = new IssuerAndSerialNumber( tbscertificatestructure.getIssuer(), tbscertificatestructure.getSerialNumber().getValue()); Cipher cipher = Cipher.getInstance(algorithmidentifier.getObjectId().getId()); cipher.init(1, x509certificate.getPublicKey()); DEROctetString deroctetstring = new DEROctetString(cipher.doFinal(abyte0)); RecipientIdentifier recipId = new RecipientIdentifier(issuerandserialnumber); return new KeyTransRecipientInfo(recipId, algorithmidentifier, deroctetstring); }