Are we becoming a paperless society? Is biometrics the bane of our existence? The expression “time will tell” has already been proven obsolete. Biometric handwriting identification is creating a sundry of perplexing problems for questioned document examiners.
The fundamental process of handwriting identification and authentication is in comparing the questioned handwriting to known contemporaneous verified handwriting of an individual. These “known” to be authentic handwriting samples are called “standards” or “exemplars”. Finding similarities as well as dissimilarities in the slant, letter heights, strokes, speed, pressure patterns, spacing and overall size of the handwriting (to name a few) is a daunting task under normal circumstances.
In order to establish a document was written by a particular person, an examination of known, verified, genuine writing must be provided. The writing must show substantial agreement without unexplainable differences. Substantial agreement in sufficient handwriting characteristics is needed to identify the maker and eliminate the possibility of any other writer. Pattern recognition in the questioned and known writing as well as the writing habits in both the known and questioned specimens are scrutinized and must be in agreement.
Normal variation in natural writing is the variance in strokes, forms and features found in handwriting. This variance occurs due to the inherent inability of the human hand to write with such mechanical precision as to exactly reproduce the many varied characteristics in an individual’s handwriting. Therefore natural variation is anticipated.
Now comes the digital age to totally confound the process.
Why are the individual stylized characteristics in handwriting important when addressing biometrics? Historically, our legal system was founded on the principal that an individual’s signature is inherently unique and identifiable. Our signature is one of the biometrics of human behavior. Our handwriting is stylized and a tangible indicator that the individual signer on a document, check, Will, credit card receipt, notarized statement, promissory note or any other document is honoring mutually agreed-upon terms or stating or addressing a subject to which we acknowledge ourselves as being the writer. With the digital age, digital signatures are coming into question all too frequently because individual characteristics are not, in most cases, readily identifiable.
Biometric Signature Recognition
What the heck is biometric signature recognition? Biometric signature recognition is the scanning of an individual’s signature, matching it electronically against a database of an individual’s known signature. When an individual signs an electronic keypad at the store, Post Office, special delivery services and other point of sale locations, allegedly, the signature is compared to others on file in a data base to determine authenticity. Traditionally, biometric technology simply tests two signatures for a match. Given that handwriting is subject to natural variation, this process becomes dubious at best. Given the technological differences in the manufacturing of various types of keypads, this process leaves much to be desired.
Biometric Algorithms
A secret code called a biometric encryption code is embedded in the software template. Supposedly, only with a corresponding image of the individual’s known writing can the code be decrypted. The encryption algorithm addresses slight variations in the handwriting allowing for a match and decryption. Hopefully.
Visualize that you are in a hurry and just scribbled your name on a digital keypad at the electronics store. You just purchased a 42″ flat screen television. You can’t wait to get home to install your new system. Two weeks later the bill arrives. There are two flat screen televisions on the bill. One TV is the 42″ for $699.99 and there is another charge for a 60″ flat screen for $1,500.00. You immediately call the store. They inform you that indeed you purchased the 60″ flat screen. This is substantiated by the fact that they have your signature “on file”. You immediately disagree and call the credit card company demanding to see the signature on the “receipt”. The credit card company sends you what appears to be a signature written by an alien life form. You then notice that it appears incredibly similar to at least two hundred other illegible signatures you previously signed on keypads. You are appalled, now questioning why you were so careless not reviewing the paperwork and not being more careful in the past when signing your name.
Another 30 days pass and the credit card company informs you they support the store and you are responsible for the $1,500. Really? Now it’s up to you to prove it’s not your signature. But how? Even though it doesn’t appear to totally resemble your signature, there are some similarities and the “system” has verified your signature as authentic.
Now imagine the converse. You are a business owner. You enter into a contract with a client. He signs the contract on your Ipad using his finger. After a week or two, the client decides he can get a better deal somewhere else and denies signing the contract. The client states you forged his signature. The illegibility of the signature when compared to his known writing could possibly provide the artillery to back out of the contract. How can a document examiner prove the client
signed the contract if there is no similarity between the known and questioned signatures due to the poor quality of the digital signature? Ugh…..so much for the digital experience.
Biometric Signature Recognition can be divided into two categories
Online recognition and offline recognition. Online recognition is behavioral. It focuses on how a signature is created. Online refers to the process that the signer used to create his or her signature, whether a pen, finger, pencil or stylus. Online signature recognition is more reliable since it is not only based on the final results of the signature, but also the behavior patterns of the signature itself. Some of the patterns referenced above are strokes, speed, pressure, letter heights, spacing, slant and unique letter formations.
Online signature recognition (dynamic) raises the level of security and reduces the chances of forgery with the use of biometric encryption techniques. Identifying differences or similarities in handwriting characteristics and our ability as forensic document examiners to effectively do so with any accuracy is determined by the quality of the questioned signature and the standards by which we make our comparisons. Online signature recognition concentrates on the dynamic aspects of the signing action that are captured directly on the keypad, real time.
Offline signature recognition (static)is based on analyzing the outcome of the signature. Offline analyzes an image statistically just dealing with images from scanners or a camera. Offline does not analyze the handwriting speed and other given characteristics. Offline is problematic because it is recovered in only grey pixels. Offline cannot analyze pressure patterns, “weight” of the drawn line, slant of the letters, speed or other “dynamic” features necessary to examine and opine as to whether a signature or handwriting is authentic.
The internal processor
The internal processor of the key pad device employs a certain technical order in which to produce the handwriting in digital form. The signature is produced by a set of data points-like connect the dots-that are connected when pressure is placed on the surface of the keypad. Some keypads cannot capture the data points under certain circumstances. Lack of speed of the processor and inadvertent pen lifts create “spaces” in the flow of the writing almost like a dotted line. Another aspect worth consideration is the accidental touch on the keypad. Resting one’s palm or pinky for leverage when signing on a keypad surface placed at an unusual angle can cause an accidental stroke or “smudge”.
The stylus, finger or other writing implement may have touched the pad too lightly or too fast. The keypad may not be sensitive enough to capture all the pressure points, therefore the data points would be inadequate and the writing would look unnatural; not smooth. This is typical of portable signature keypads.
There are some devices that will predetermine whether or not to add characteristics to the writing if spaces from lack of pressure of the writing implement to the surface should occur. The software can automatically create a curve or straight line in order to make the adjustment in creating a more natural looking effect. This is highly problematic for document examiners. As a
result, this automatic process of filling in the blank spaces where the data points fail to connect, alters one’s signature and identification is often, not possible. Since most individuals do not take the time or make the effort to provide an accurate, legible signature on the digital keypad, the consequences can be dire.
Several other factors also contribute to an illegible digital signature. Most often, the keypad is not situated in a location that is easily accessible. The keypad is sometimes elevated above a countertop or more toward the cash register thereby causing an unnatural angle of the wrist and hand. In portable keypads such as used in deliveries to one’s door, holding the keypad in one hand while trying to sign one’s name is a juggling act at best. Most just scribble a signature and call it a day! Think twice about ever doing that again.
In addition, depending on the equipment, the pen tip on the keypad surface may be lacking or malfunctioning, thus providing a signature that appears to look dotted or angular.
These examples of digital key pads were provided with permission and courtesy of Topaz Systems.
“The upper reference signature is used to compare the authenticity of the lower questioned signature. The lower signature is very likely to be false, because while similar in shape, it exhibits the “slow signing effect” typical of the actions of a forger.” Topaz Systems.
In 2012, in a United States Federal Court case regarding a digital questioned signature, the Southern District of Mississippi, Jackson Division court upheld the testimony of the expert forensic document examiner in a Daubert Hearing. The examiner determined the questioned signature was authentic which was supported by the court.
The three prongs of a Daubert Challenge are:
Testimony must be based on the preponderance of facts and data.
The expert relied on generally accepted principles and methods in the scientific community. Has the
theory or technique been empirically tested?
The expert has to employ generally accepted principles and methods in order to reach a conclusion.
Has the theory or technique been peer reviewed?
Upholding the expert’s testimony, the Federal Court set a precedence confirming the validity of the role of Forensic Document Examiners in the digital arena. That being stated, it would behoove the public to be cognizant of their signatures, making every effort to write consistently legible. Should the point of sale software fail to recognize the differences in an authentic signature from that of a forger, having a legible and distinct signature could make all the difference.
By
E’lyn Bryan CFDE,BAI
Certified Forensic Document Examiner
Board Accredited Investigator
Copyright 2014
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