Digital inking systems are becoming increasingly popular across a variety of domains. In particular, many systems now allow instructors to write on digital surfaces in the classroom. Yet our understanding of how people actually use writing in these systems is limited. For an example, we report on classroom use of writing in one such system, in which the instructor annotates projected slides using a Tablet PC. Digital inking systems (computer applications that accept pen based written input) promise infinite malleability and detailed archiving of ink. Ink can change colors, be moved and resized and transformed into typeset text. Inking systems can record time, pressure, context, and other information for every stroke drawn. Digital ink technologies have evolved over time and include cameras, touch sensitive whiteboards, PDA's, Tablet PC's, and digital pens. Systems using these technologies support note taking and sharing, real-time distributed conversation and meetings and classroom presentation and capture.

Inking is a broad term that actually represents a set of technologies. To make inking work properly there are a number of technologies which should work together. Generally Microsoft Research teams were involved in solving the technological challenges that came together as inking.

First of all, one has to look at the hardware considerations because this input screen should have some special features. An electromagnetic field has to be created by a digitizer overlain on the LCD screen of Tablet PC's. As soon as the pen touches the screen, it comes in contact with the electromagnetic field of that screen and then a series of data points on the screen prove the reflection of its motion. Via a special process, which is known as sampling, the digitizer gathers information from movement of the pen when it continues to move across the screen. The sampling capacity of Tablet PC digitizer is 130 "pen events" -- units per second. These electromagnetic pen events are then visualized on the screen as pen strokes.

As the user writes on the LCD screen, digital ink appears to flow at the same speed that the pen writes on the screen, (as it has a high sampling rate), thus the Tablet PC is able to create the effect of "real-time inking."

Another advantage of this high capacity of sampling rate is that it makes the written ink able to be displayed and stored with very high graphical resolution. This is very important for visual legibility on the screen and also essential for maximizing the accuracy during the process of handwriting recognition. However, we should remember that the handwriting recognition is inherently a statistical process. For some users it will work nicely, but for others it may not.

Another thing to remember is each of the supported languages, such as American and International English, German, French, Japanese, etc. has its own recognizer engine which stores handwriting samples that are language-specific.

In the handwriting recognition technology the inking process enables the users to convert the handwritten data to standard text. Users can also store the data in its ink format without loosing its functionality. Written ink need not be converted to a different format if it has to be saved, sent, sized or manipulated by Windows-based applications or exported across Windows platforms.

Digital ink can be transferred from application to application as digital ink. This proves that the Tablet PC works more than just a handwriting recognition tool.   In the future, these technologies have a large scope.

Digital Ink Signatures

The Tablet PC is the tool for digital forms-based data collection processes. There should be some degree of authentication while providing the means to collect, validate, and store data, digital forms. Pen-based signatures used to be one of the oldest methods of authentication. Upcoming technology is electronic signatures created with a digital pen in Tablet PC applications which is used for collection, preservation, and protection. The design and implementation of Tablet PC applications where pen-based signatures is there provides useful functionality. As businesses continue to replace paper documents, contracts, and forms with more efficient and cost-effective electronic substitutes, electronic signature technology becomes an increasingly important investment. The cost and time savings of doing business electronically are evident across many sectors and industries, yet many companies are still choosing which technology or method is best suited to their needs. Creating, signing, transmitting, and storing any and all documents electronically and in such a way as to be legally-binding can seem like a daunting task, especially for small to medium-sized businesses.

The term digital signatures or e-signatures can be used interchangeably to refer to digital certificates administered by trusted third parties ("certificate authorities") and similar technologies, as well as digital ink signatures created on the Tablet PC.

Leading-edge organizations moving forward with Electronic Signatures:

High performing enterprises maintain their edge by quickly seizing upon the opportunity to create worthwhile operating efficiencies while maintaining or ideally enhancing the experience for their customers. Because of the widely known efficiencies gained from e-Commerce and paper eradication, Electronic Signatures is clearly one of these opportunities. In moving forward with electronic signatures these enterprises have thoughtfully considered the following.

1) The application and user requirements

Examples:

Internet

Signing a form, document, or

2) The operating environment and system integration

Examples:

Based on Internet Browser

Adobe Acrobat PDF form

Microsoft Word Document

Custom application

Win 2000, Unix, Palm OS, or others

The future needs to expand or merge the electronic signature application.

Laws and regulations of applicable states and agencies, since in addition to state laws there may be regulatory bodies within a particular industry that need to be considered. With this analysis, it becomes easier to focus on the right technology partner.

In the United States, electronic signatures are covered under the Uniform Electronic Transactions Act and Electronic Signatures in Global and National Commerce law. Passed by the US Congress in 1999 and 2000, respectively, these two laws serve as the framework for electronic commerce implementation in the United States, as most state-level E-commerce laws are identical to Uniform Electronic Transactions Act or a slightly altered version. These laws specify exactly what constitutes a valid electronic signature, as well as the conditions under which it is legally binding. An electronic signature is a “sound, symbol, or process, logically associated with a document” such that it is:

unique to each user

under the sole control of the signer

linked to a document in such a way as to prevent tampering, and

capable of being authenticated

Several different methods and technologies exist for attaching electronic signatures to documents according to these stipulations. Two common types of signature technologies that are widely available, yet differ greatly in substance, are PIN/Password signature stamps and digitized handwritten signatures. A PIN/Password stamp inserts a single fixed signature image into each signed document when a user types a password or PIN. Digitized handwritten signatures are captured with special pen-and-tablet systems that convert a user’s signature accurately into pen events or a summary image. These methods have different ramifications for security and authentication.

What happens when we bypass PIN/Password

While companies that provide PIN signature stamps may claim that their technology is legally-compliant because it qualifies as an "electronic sound, symbol, or process," it falls far short of the holistic requirements enumerated above. As a practical point, each and every one of these "signatures" is identical in form and composition, as if they were made with a single rubber stamp. The appearance of the signature on a document is not a record of a person’s signature, but rather a result of a particular password being typed. A forensic examiner that views the signature image cannot determine its point of origin since any person could have typed the PIN or password. As such, PIN signature stamps fall short of the authentication requirements of criterion (4) listed above. Should a password become compromised, each and every document a person had ever signed with the PIN method would be questionable, since each signature appears identical and it cannot be proven which are authentic and which are fraudulent. For these reasons, businesses are advised to invest in an electronic signature technology that creates a unique electronic record for each signing instance and not to rely on a "rubber stamp" technology. PKI digital signatures and certificates are simply a more complex version of "rubber stamp" technology, except that a larger (often 128-bit) encryption number is used, meaning it is too large to be remembered and typed. Portability is also limited because the key is permanently linked to a host computer or a "secure" smart card which can be lost, stolen, or hacked.

A better choice for electronic commerce, especially with interactions involving the general public, is handwritten signature devices and software. While the use of any pen-and-tablet signature technology may seem to be the logical replacement for traditional "wet" ink-on-paper signatures, there are several issues to consider when choosing a system for your business. Signature capture hardware manufacturers have their own specifications, data formats, and software methodologies that affect security, authentication, and legality.

For the sake of privacy and legal enforceability, an electronic signature must remain under the “sole control of the signer” to be valid under the national ESIGN electronic commerce law. To satisfy this requirement, a signature must be placed or linked into the relevant document directly, with no interlopers or copies, and then bound to the document in such a way as to render document tampering detectable. Without these critical features, it would not be possible to prove that a signatory did indeed assent to the terms of the written agreement or that the language in the document was identical in form to the state in which it was initially signed.

On the other hand, there is value in monitoring and evaluating the integrity of data received from a signature pad, such as the point sampling rate, and detection of unusual time-related activity in signing.

Document security and signature binding are also important. If the signature is not linked to the contents of the written agreement, it has no real value since there would be no evidence of tampering or changes made to the terms post signing.

An important characteristic of ink-on-paper signatures is that they can be individually studied and analyzed by forensic handwriting experts, then compared to other existing samples for authentication. Perhaps the most significant challenge to the validity of an electronic signature is the issue of authentication, since few technology providers support their technology with verification tools. If a signature cannot be attributed to the purported signatory, it is worthless. Electronic signatures are no exception to this, and must be capable of authentication to be valid and binding. Insist that a technology provider have authentication tools and training in-place before selecting their solution.

The most accurate, reliable, and secure method of capturing a signature is in the form of raw pen events. A file of this type contains no images or analysis of the signature, just the pen events and position converted at high speed. This data has the additional advantage of being stored in a database or bound to the contents of a document very securely. It cannot be easily copied or viewed and used as a reference for forgers since there is no embedded image. Furthermore, all original captured pen events are present in the e-signature itself.

We can generalize by mentioning that, when deciding which electronic signature system best suits the needs of a business, one should use traditional paper-based practices as a gold standard. If a specific technology mimics or matches these practices closely, it is probably a safe and reliable choice. The more technical shortcuts a system employs, such as creating multiple signatures with one stroke of a pen or keypad, or saving  images in place of real signatures, the more likely the system is to encounter difficulties and fraud in practice. With old ink-on-paper characteristics as one’s guide, electronic document solution should be a signature success.