iTextSharp.text.pdf.PdfEncryption.SetupAllKeys C# (CSharp) Метод

        public void SetupAllKeys(byte[] userPassword, byte[] ownerPassword, int permissions)
        {
            if (ownerPassword == null || ownerPassword.Length == 0)
            ownerPassword = DigestAlgorithms.Digest("MD5", CreateDocumentId());
            md5.Reset();
            permissions |= (int)((revision == STANDARD_ENCRYPTION_128 || revision == AES_128 || revision == AES_256) ? (uint)0xfffff0c0 : (uint)0xffffffc0);
            permissions &= unchecked((int)0xfffffffc);
            this.permissions = permissions;
            if (revision == AES_256) {
            if (userPassword == null)
                userPassword = new byte[0];
            documentID = CreateDocumentId();
            byte[] uvs = IVGenerator.GetIV(8);
            byte[] uks = IVGenerator.GetIV(8);
            key = IVGenerator.GetIV(32);
            // Algorithm 3.8.1
            IDigest md = DigestUtilities.GetDigest("SHA-256");
            md.BlockUpdate(userPassword, 0, Math.Min(userPassword.Length, 127));
            md.BlockUpdate(uvs, 0, uvs.Length);
            userKey = new byte[48];
            md.DoFinal(userKey, 0);
            System.Array.Copy(uvs, 0, userKey, 32, 8);
            System.Array.Copy(uks, 0, userKey, 40, 8);
            // Algorithm 3.8.2
            md.BlockUpdate(userPassword, 0, Math.Min(userPassword.Length, 127));
            md.BlockUpdate(uks, 0, uks.Length);
            byte[] tempDigest = new byte[32];
            md.DoFinal(tempDigest, 0);
            AESCipherCBCnoPad ac = new AESCipherCBCnoPad(true, tempDigest);
            ueKey = ac.ProcessBlock(key, 0, key.Length);
            // Algorithm 3.9.1
            byte[] ovs = IVGenerator.GetIV(8);
            byte[] oks = IVGenerator.GetIV(8);
            md.BlockUpdate(ownerPassword, 0, Math.Min(ownerPassword.Length, 127));
            md.BlockUpdate(ovs, 0, ovs.Length);
            md.BlockUpdate(userKey, 0, userKey.Length);
            ownerKey = new byte[48];
            md.DoFinal(ownerKey, 0);
            System.Array.Copy(ovs, 0, ownerKey, 32, 8);
            System.Array.Copy(oks, 0, ownerKey, 40, 8);
            // Algorithm 3.9.2
            md.BlockUpdate(ownerPassword, 0, Math.Min(ownerPassword.Length, 127));
            md.BlockUpdate(oks, 0, oks.Length);
            md.BlockUpdate(userKey, 0, userKey.Length);
            md.DoFinal(tempDigest, 0);
            ac = new AESCipherCBCnoPad(true, tempDigest);
            oeKey = ac.ProcessBlock(key, 0, key.Length);
            // Algorithm 3.10
            byte[] permsp = IVGenerator.GetIV(16);
            permsp[0] = (byte)permissions;
            permsp[1] = (byte)(permissions >> 8);
            permsp[2] = (byte)(permissions >> 16);
            permsp[3] = (byte)(permissions >> 24);
            permsp[4] = (byte)(255);
            permsp[5] = (byte)(255);
            permsp[6] = (byte)(255);
            permsp[7] = (byte)(255);
            permsp[8] = encryptMetadata ? (byte)'T' : (byte)'F';
            permsp[9] = (byte)'a';
            permsp[10] = (byte)'d';
            permsp[11] = (byte)'b';
            ac = new AESCipherCBCnoPad(true, key);
            perms = ac.ProcessBlock(permsp, 0, permsp.Length);
            }
            else {
            //PDF refrence 3.5.2 Standard Security Handler, Algorithum 3.3-1
            //If there is no owner password, use the user password instead.
            byte[] userPad = PadPassword(userPassword);
            byte[] ownerPad = PadPassword(ownerPassword);

            this.ownerKey = ComputeOwnerKey(userPad, ownerPad);
            documentID = CreateDocumentId();
            SetupByUserPad(this.documentID, userPad, this.ownerKey, permissions);
            }
        }

 /** Sets the encryption options for this document. The userPassword and the
 *  ownerPassword can be null or have zero length. In this case the ownerPassword
 *  is replaced by a random string. The open permissions for the document can be
 *  AllowPrinting, AllowModifyContents, AllowCopy, AllowModifyAnnotations,
 *  AllowFillIn, AllowScreenReaders, AllowAssembly and AllowDegradedPrinting.
 *  The permissions can be combined by ORing them.
 * @param userPassword the user password. Can be null or empty
 * @param ownerPassword the owner password. Can be null or empty
 * @param permissions the user permissions
 * @param encryptionType the type of encryption. It can be one of STANDARD_ENCRYPTION_40, STANDARD_ENCRYPTION_128 or ENCRYPTION_AES128.
 * Optionally DO_NOT_ENCRYPT_METADATA can be ored to output the metadata in cleartext
 * @throws DocumentException if the document is already open
 */
 public void SetEncryption(byte[] userPassword, byte[] ownerPassword, int permissions, int encryptionType) {
     if (pdf.IsOpen())
         throw new DocumentException(MessageLocalization.GetComposedMessage("encryption.can.only.be.added.before.opening.the.document"));
     crypto = new PdfEncryption();
     crypto.SetCryptoMode(encryptionType, 0);
     crypto.SetupAllKeys(userPassword, ownerPassword, permissions);
 }