Signature pad
A signature pad , signature pad , signature tablet , or Pen Pad is a device that has been developed exclusively for personal signatures electronically to detect. In combination with digital signatures , electronically recorded signatures are used to sign or sign electronic documents and thus avoid a media break from electronic to paper document and back. Insofar as pads also enable dynamic biometric data to be recorded, such a biometric signature, which is usually encoded in the electronic document, can be used as an identification feature for later identification of the signatory. The signature pads were never able to establish themselves across the board and have been losing importance again since the 2010s with the triumph of smartphones and tablets .
Intended use
So far, some companies use the cumbersome and expensive way of electronically created documents that must be signed to print to let then write to them then for the space-saving archiving again scan . This classic media break from electronic to paper-based back to electronic is time-consuming and at the same time leads to a loss of evidential value when scanning the signature and does not exempt the signed paper documents from having to be stored for many types of documents (e.g. contracts).
In many cases, this has now been avoided by using signature pads and appropriate signature software. Electronic documents are electronically signed as well as digitally signed using a signature pad and can then be electronically saved, archived or further processed without media discontinuity.
Signed on signature pads today and a. Applications to open an account, to take out insurance or a telecommunications contract, receipts for deposits, withdrawals and electronic direct debit, documents from internal administration (permits, loans, etc.), protocols to prove that services have been provided, documentation of inspection processes or visitor management ( Day passes).
functionality
Depending on the manufacturer, a signature pad records not only the high-resolution typeface with up to 1000 dpi but also the pressure curve with up to 1024 pressure levels and, with some technologies, the movements in the air (airmovement) up to about one cm from the surface. The electronic timing of a signature pads - also sampling or sample rate called - allows using the modified at any point pen position (x, y) between two pin positions for both the calculation of the writing speed and the writing direction and a plurality of pin positions the calculation of the accelerations , decelerations and the writing pauses of a signature.
Some of the pads work with a real sampling rate of up to 500 measurements per second , but there are also devices for which the manufacturer's information on the sample rate is based solely on interpolated values.
Writing pressure (z or p for pressure) and the time-dependent data are referred to as writing dynamics, the two-dimensional image without a time stamp of the data points of the signature is referred to as static biometric data.
The most important static and dynamic biometric features, which can be derived from the data electronically recorded via a signature pad, are summarized:
- two-dimensional typeface of the signature (pattern recognition)
- Writing speed
- Writing direction
- Order of the segments
- Writing breaks
- Pressure curve.
Even if a person were to imitate a visually very similar typeface to the signature of another person, from a certain complexity of the signature he could only do it with a completely different pressure and speed curve. As a rule, such a counterfeit biometric signature would be recognized as a forgery by a handwriting expert when compared .
For the forensic analysis of signature data, appropriate computer programs are available for handwriting experts, which in particular visualize the dynamic biometric signature aspects. Some programs can also compare signature data automatically, this is called verification.
The quality and quantity of the biometric data and thus the signature can already be checked during the acquisition, for example in order to naturally reject short paraphs (signature abbreviations ). The desired quality of the biometric data transmitted by the signature pad can in turn be adjusted, at least in the case of some pads, in accordance with the selection of the recording devices and the desired security level.
Variants of detection devices
Pads without detection of pressure-sensitive features
Such pads are mostly used by parcel deliverers . They are also widely available in stores in the United States. Essentially, the x / y positions are recorded and the typeface, writing speed, writing direction and writing pauses are calculated from them. The recorded signature can u. a. be used for the purpose of possible evidence in the sense of a receipt to the parcel recipient or as proof that the deliverer actually handed over the parcel. However, the statement made by the deliverer and not the signature is still relevant for proof of delivery.
Pads with pressure sensitive pens
With this type of device, the writing pressure is recorded by a sensor in a special pen ("digitizer"). The pen is electronically powered by a cable connection, battery or induction. The position of the sensor in the pen is advantageous for capturing information about the pressure levels used while signing: In contrast to other technologies, when the heel of the hand is placed when signing, no falsifying signal data is generated.
This technology is not only used on signature pads, but is also used on many tablet PCs .
Pads with pressure-sensitive writing surface without display
In the mid-1990s there were already the first pure signature pads from Germany, but these were based on load cell technology. With an appropriate driver software, the respective xy position and the writing pressure could be calculated from the different loads on the four load cells during the signing. However, these pads were not able to establish themselves technically because the driver software for the load cells had to be calibrated for each individual pad and the as yet undeveloped signature market prevented an investment in the series production of the load cells.
At the beginning of the new millennium, the first pads came onto the market, which, similar to a touchscreen, now also have a pressure-sensitive writing surface without the writing surface of the pad moving while writing. This technology has been known in the USA since the mid-1980s. But have clearly been overtaken by the pads with display.
Pads with liquid crystal display or e-ink
All of the pads described above demanded the display of the signature on the screen, which usually led to irritation and inaccurate signature acceptance by the signatories, as they had to "blindly" sign on the respective pads. This applied equally to pads with pressure-sensitive pens and pads with pressure-sensitive writing surfaces.
An alternative are pads with LC displays , which have also been available on the market since the mid-1990s and which display the signature in real time directly under the pen in two dimensions, regardless of the recording of the writing pressure when signing. This makes the signatories feel much more secure, which also increases trust in their own signature.
These devices are available in different sizes - as pure signature pads or for graphic applications.
Manufacturer
There are relatively few manufacturers of signature pads in the world. The three dominant manufacturers of pure signature pads come from Germany (StepOver), Japan (WACOM) and the USA (Topaz). The German company signotec has also been offering its own signature pads since 2009. There are also several different manufacturers, e.g. B. Motiontouch from Great Britain or Taiwan, which however, due to various patents, are essentially based on the technologies of the three main providers. The American manufacturer Interlink was bought by Topaz in 2009.
Range of devices and quality
The pads from the manufacturers differ in the way in which the data is recorded; in some cases, the data is transferred point by point to the application (stream) or completely recorded in the pad and transmitted as a data packet. This is u. a. due to the fact that the respective pads were designed and produced in accordance with the legal and social framework conditions of their main sales markets. As an example, it should be mentioned that with some devices the detection of the pressure intensity with resistive sensor technology is different at different points on the detection surface, with EMR (electromagnetic resonance technology) the pressure is linear because it is measured via the pen.
Evidence of biometric signatures
Based on Article 5.2 of the EU Directive of 1999, certificate-free electronic signatures are generally permitted as evidence in court under German law . However, since German judges are free to assess evidence according to ZPO § 286, the respective judge could ignore the signatures introduced. Ultimately, the respective judge decides on the evidential value of an electronic signature. It is therefore important to convince the court of the evidential value of the electronic signatures and the associated biometric data. I. d. As a rule, if necessary, a forensic handwriting expert is commissioned with identification using biometric data from a signature, as is the case with paper.
In the case of electronic signatures with biometric signatures, the evidential value of the signature identifier depends on the quality of the biometric data recorded. As the values supplied by the signature pad increase, so does the accuracy and thus the quality of the biometric signature data.
Individual evidence
- ↑ Directive 99/93 / EG (PDF) for electronic signatures
- ↑ BGB § 127 - Agreed form