Tactility
Tactile (touchable) property of an object. Tactile security features include intaglio printing = FIT^®.


Tape sensor
Special sensor for recognizing adhesive tape on banknotes.


TCP
The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. Using TCP, programs on networked computers can create connections to one another, over which they can send data. The protocol guarantees that data sent by one endpoint will be received in the same order by the other, and without any pieces missing. It also distinguishes data for different applications (such as a web server and an email server) on the same computer. TCP supports many of the Internet's most popular applications, including HTTP, SMTP, and SSH.


TCP/IP
Short for “Transmission Control Protocol over Internet Protocol” – standard protocol suite on the Internet/intranet as well as WAN and UNIX networks. The Internet Protocol (IP) is used for fragmenting and addressing data and transmits it from the sender to the recipient, although it does not secure the transmission. The Transmission Control Protocol (TCP) builds on this and is responsible for sorting the packets in the right sequence at the recipient end while securing the communication by confirming the packet receiver. It corrects transmission errors automatically. The PPP (Point to Point Protocol) is a recent addition to TCP/IP, which also permits network communications over modems.


TCSEC
The “Information Technique System Evaluation Criteria” were published in 1985 by NCSC and consist of a catalog of criteria for evaluating and certifying the security of information systems in the United States. The successors to the national TCSEC are the international Common Criteria.


TDES
see Triple DES


Terminal
The single connection of a chip card with the outside world is a so-called serial interface. The electronic connection sets up terminals that vary in appearance and function. There are portable and stationary versions and they can be operated either online or offline. Offline terminals are fully autonomous, while online versions are controlled by a background system (a host computer). For security reasons, EC terminals in Germany work almost exclusively online since the magnetic stripe cards widely used there are passive elements and therefore not suitable for offline operation. The situation is somewhat different for newly installed payment transaction systems based on chip cards: As active components, chip cards can protect themselves against attack and identify their transaction partners – such as the terminal. The security information, such as the secret key on the chip, is stored in both the terminal and the card, protected from illegal access and manipulation. On the terminal side, this key is located on the so-called “merchant card” or SAM (Secure Application Module). This card is usually inserted into the terminal as a compact plug-in card, such as those used in cell phones.

Testing
Testing means checking the functionality of a previously debugged program. The main aim is not to look for errors in the program, but to test the expected functions. Testing is therefore not the same thing as debugging.


TPDU
see APDU


Transaction number (TAN)
Unlike a PIN, a TAN is only valid for a single transaction and can therefore only be used once. You normally get several TANs (e.g. in the form of a four-digit number) printed on paper, which must then be used in the exact sequence specified for the individual transactions or sessions.


Transfer element
Film transferred on to a substrate by means of hot stamping. A distinction is made here between registration-compliant transfers (e.g. patches on 50 euro banknotes) and non-registration compliant transfers (e.g. LEAD stripes on 5 euro banknotes).


Translucence
Synthetic translucence, semi-transparency: materials that light can shine through, whereby the objects behind the translucent material are seen only diffusely or not at all – unlike with transparency. A typical percentage of translucence or semi-transparency is in metallized applications with a light transparency of around 20-80%.


Transmission hologram
In order for a transmission hologram to be projected, the illumination, as with a slide, must pass through the hologram from behind (cf. reflection hologram).


Transmission protocol
In the smart card world, ‘transmission protocol’ refers to the mechanisms used for transmitting and receiving data between a terminal and a smart card. The transmission protocol describes in detail the OSI protocol layers, the data exchange in successful transmissions, error detection mechanisms, and response mechanisms in the event of errors.

Transparency
A material that is completely see-through, for example, clear window glass, as opposed to only partial transparency (translucence), such as frosted glass, tinted windows, or films.


Transport protocol
Another term for transmission protocol (see Transmission protocol).


Trapdoor
Mechanism deliberately created in a software application or algorithm that can be used to circumvent security functions and protection mechanisms.


Triple DES
The Triple DES, also called TDES or 3DES, is a modified DES encryption in which the DES algorithm is run three times in succession with alternate encryption and decryption. If the same key is used for all three DES calls, the triple DES encryption then corresponds to normal DES encryption. However, if two or three different keys are used, this reinforces the DES encryption considerably compared to simple DES encryption.


Trojan
In computer language, a Trojan horse is a program that is disguised as a legitimate program, but which in fact smuggles malware (malicious software) on to your computer where it runs undesirable hidden actions.
The program has a legitimate function or at least purports to have one. However, the Trojan horse secretly runs other, undesirable functions. The legitimate or purportedly legitimate functions are only used to disguise these undesirable functions. These can be of any nature imaginable.


Trojan horse
Same as a Trojan: In Greek legend, the Trojan horse was used by Odysseus to gain entry to the strongly fortified city of Troy. Its modern incarnation is a program that carries out a defined task in the foreground, while running other unknown functions in the background. It is deliberately imported into a computer system or host program and unlike a virus cannot replicate itself.