iTextSharp.text.pdf.crypto.AESCipherCBCnoPad.ProcessBlock C# (CSharp) 메소드

        public byte[] ProcessBlock(byte[] inp, int inpOff, int inpLen)
        {
            if ((inpLen % cbc.GetBlockSize()) != 0)
                throw new ArgumentException("Not multiple of block: " + inpLen);
            byte[] outp = new byte[inpLen];
            int baseOffset = 0;
            while (inpLen > 0) {
                cbc.ProcessBlock(inp, inpOff, outp, baseOffset);
                inpLen -= cbc.GetBlockSize();
                baseOffset += cbc.GetBlockSize();
                inpOff += cbc.GetBlockSize();
            }
            return outp;
        }

 virtual public bool ReadKey(PdfDictionary enc, byte[] password) {
     if (password == null)
         password = new byte[0];
     byte[] oValue = DocWriter.GetISOBytes(enc.Get(PdfName.O).ToString());
     byte[] uValue = DocWriter.GetISOBytes(enc.Get(PdfName.U).ToString());
     byte[] oeValue = DocWriter.GetISOBytes(enc.Get(PdfName.OE).ToString());
     byte[] ueValue = DocWriter.GetISOBytes(enc.Get(PdfName.UE).ToString());
     byte[] perms = DocWriter.GetISOBytes(enc.Get(PdfName.PERMS).ToString());
     bool isUserPass = false;
     IDigest md = DigestUtilities.GetDigest("SHA-256");
     md.BlockUpdate(password, 0, Math.Min(password.Length, 127));
     md.BlockUpdate(oValue, VALIDATION_SALT_OFFSET, SALT_LENGHT);
     md.BlockUpdate(uValue, 0, OU_LENGHT);
     byte[] hash = DigestUtilities.DoFinal(md);
     bool isOwnerPass = CompareArray(hash, oValue, 32);
     AESCipherCBCnoPad ac;
     if (isOwnerPass) {
         md.BlockUpdate(password, 0, Math.Min(password.Length, 127));
         md.BlockUpdate(oValue, KEY_SALT_OFFSET, SALT_LENGHT);
         md.BlockUpdate(uValue, 0, OU_LENGHT);
         md.DoFinal(hash, 0);
         ac = new AESCipherCBCnoPad(false, hash);
         key = ac.ProcessBlock(oeValue, 0, oeValue.Length);
     }
     else {
         md.BlockUpdate(password, 0, Math.Min(password.Length, 127));
         md.BlockUpdate(uValue, VALIDATION_SALT_OFFSET, SALT_LENGHT);
         md.DoFinal(hash, 0);
         isUserPass = CompareArray(hash, uValue, 32);
         if (!isUserPass)
             throw new BadPasswordException(MessageLocalization.GetComposedMessage("bad.user.password"));
         md.BlockUpdate(password, 0, Math.Min(password.Length, 127));
         md.BlockUpdate(uValue, KEY_SALT_OFFSET, SALT_LENGHT);
         md.DoFinal(hash, 0);
         ac = new AESCipherCBCnoPad(false, hash);
         key = ac.ProcessBlock(ueValue, 0, ueValue.Length);
     }
     ac = new AESCipherCBCnoPad(false, key);
     byte[] decPerms = ac.ProcessBlock(perms, 0, perms.Length);
     if (decPerms[9] != (byte)'a' || decPerms[10] != (byte)'d' || decPerms[11] != (byte)'b')
         throw new BadPasswordException(MessageLocalization.GetComposedMessage("bad.user.password"));
     permissions = (decPerms[0] & 0xff) | ((decPerms[1] & 0xff) << 8)
             | ((decPerms[2] & 0xff) << 16) | ((decPerms[2] & 0xff) << 24);
     encryptMetadata = decPerms[8] == (byte)'T';
     return isOwnerPass;
 }