ISO/IEC DIS 19794-7

Information technology -- Biometric data interchange formats

Technologies de l'information -- Formats d'échange de données biométriques

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 19794-7
ISO/IEC JTC 1/SC 37 Secretariat: ANSI
Voting begins on: Voting terminates on:
2020-06-09 2020-09-01
Information technology — Biometric data interchange
formats —
Part 7:
Signature/sign time series data
Technologies de l'information — Formats d'échange de données biométriques —
Partie 7: Données de série chronologique de signature/signe
ICS: 35.240.15
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
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STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
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ISO/IEC DIS 19794-7:2020(E)
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PROVIDE SUPPORTING DOCUMENTATION. ISO/IEC 2020
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ISO/IEC DIS 19794-7:2020(E)
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© ISO/IEC 2020

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ISO/IEC DIS 19794-7:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Abbreviated terms .............................................................................................................................................................................................. 3

5 Conformance ............................................................................................................................................................................................................. 4

6 Conventions ............................................................................................................................................................................................................... 4

6.1 Coordinate system ............................................................................................................................................................................... 4

6.2 Octet and bit order ............................................................................................................................................................................... 4

6.3 Registered format type identifiers ......................................................................................................................................... 5

7 Channels ........................................................................................................................................................................................................................ 5

7.1 General ........................................................................................................................................................................................................... 5

7.2 Pen tip position channels: X, Y, Z ............................................................................................................................................. 6

7.3 Pen tip velocity channels: VX, VY ............................................................................................................................................ 6

7.4 Pen tip acceleration channels: AX, AY ................................................................................................................................. 6

7.5 Time channel: T ...................................................................................................................................................................................... 6

7.6 Time difference channel: DT ....................................................................................................................................................... 6

7.7 Pen tip force channel: F ................................................................................................................................................................... 7

7.8 Pen tip switch state channel: S .................................................................................................................................................. 7

7.9 Pen orientation channels: TX, TY, A, E, R .......................................................................................................................... 7

8 Binary full format ................................................................................................................................................................................................ 8

8.1 Record organisation ........................................................................................................................................................................... 8

8.2 General header ........................................................................................................................................................................................ 9

8.2.1 Structure ................................................................................................................................................................................. 9

8.2.2 Format identifier .............................................................................................................................................................. 9

8.2.3 Version number ................................................................................................................................................................ 9

8.2.4 Length of the data record ......................................................................................................................................10

8.2.5 Number of representations .................................................................................................................................10

8.2.6 Certification flag ............................................................................................................................................................10

8.3 Record body ............................................................................................................................................................................................10

8.3.1 Structure ..............................................................................................................................................................................10

8.3.2 Representation header ............................................................................................................................................10

8.3.3 Representation body .................................................................................................................................................15

9 Binary compact format ...............................................................................................................................................................................16

9.1 Record organisation ........................................................................................................................................................................16

9.2 Comparison algorithm parameters template ............................................................................................................17

9.2.1 Structure ..............................................................................................................................................................................17

9.2.2 Minimum and maximum number of sample points .......................................................................17

9.2.3 Channel descriptions ........................................................................................................................................... ......17

9.3 Embedment in a CBEFF data structure ...........................................................................................................................18

9.4 Record body ............................................................................................................................................................................................19

10 Binary compression format ...................................................................................................................................................................19

10.1 Record organisation ........................................................................................................................................................................19

10.2 General header .....................................................................................................................................................................................20

10.3 Record body ............................................................................................................................................................................................20

10.3.1 Structure ..............................................................................................................................................................................20

10.3.2 Representation header ............................................................................................................................................20

10.3.3 Representation body .................................................................................................................................................21

Annex A (normative) Conformance testing methodology ...........................................................................................................23

Annex B (informative) Best practices – Data acquisition .............................................................................................................68

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ISO/IEC DIS 19794-7:2020(E)

Annex C (informative) ASN.1 specification of the binary compact format .................................................................69

Annex D (informative) Signature/sign coding examples ..............................................................................................................72

Annex E (normative) XML schema definition ...........................................................................................................................................74

Annex F (informative) Sample XML encoding ..........................................................................................................................................78

Bibliography .............................................................................................................................................................................................................................80

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ISO/IEC DIS 19794-7:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical

activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the

work. In the field of information technology, ISO and IEC have established a joint technical committee,

ISO/IEC JTC 1.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for

the different types of document should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent

rights. Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 37, Biometrics.

This third edition cancels and replaces the second edition (ISO/IEC 19794-7:2014), which has been

technically revised. The main changes compared to the previous edition are as follows:

— inclusion of ISO/IEC 19794-7:2014/Amd.1:2015, XML encoding, and
— correction of technical defects therein.
A list of all parts in the ISO/IEC 19794 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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DRAFT INTERNATIONAL STANDARD ISO/IEC DIS 19794-7:2020(E)
Information technology — Biometric data interchange
formats —
Part 7:
Signature/sign time series data
1 Scope

This document specifies data interchange formats for signature/sign behavioural data captured in

the form of a multi-dimensional time series using devices such as digitizing tablets or advanced pen

systems. The data interchange formats are generic, in that they may be applied and used in a wide

range of application areas where handwritten signs or signatures are involved. No application-specific

requirements or features are addressed in this document.
This document contains
— a description of what data may be captured,

— three binary data formats for containing the data: a full format for general use, a compression format

capable of holding the same amount of information as the full format but in compressed form, and

a compact format for use with smart cards and other tokens that does not require compression/

decompression but conveys less information than the full format,
— an XML schema definition, and
— examples of data record contents and best practices in capture.

Specifying which of the format types and which options defined in this document are to be applied in

a particular application is out of scope; this needs to be defined in application-specific requirements

specifications or application profiles.

It is advisable that cryptographic techniques be used to protect the authenticity, integrity, and

confidentiality of stored and transmitted biometric data; yet such provisions are beyond the scope of

this document.

This document also specifies elements of conformance testing methodology, test assertions, and test

procedures as applicable to this document. It establishes test assertions on the structure and internal

consistency of the signature/sign time series data formats defined in this document (type A level 1

and 2 as defined in ISO/IEC 19794-1:2011/Amd.1:2013), and semantic test assertions (type A level 3 as

defined in ISO/IEC 19794-1:2011/Amd.1:2013).

The conformance testing methodology specified in this document does not establish:

— tests of other characteristics of biometric products or other types of testing of biometric products

(e.g. acceptance, performance, robustness, security),

— tests of conformance of systems that do not produce data records claimed to conform to the

requirements of this document.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
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ISO/IEC DIS 19794-7:2020(E)

ISO/IEC 8825-1, Information technology – ASN.1 encoding rules – Part 1: Specification of Basic Encoding

Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)

ISO/IEC 19785-1, Information technology – Common Biometric Exchange Formats Framework – Part 1:

Data element specification

ISO/IEC 197852, Information technology – Common Biometric Exchange Formats Framework – Part 2:

Procedures for the operation of the Biometric Registration authority

ISO/IEC 197853, Information technology – Common Biometric Exchange Formats Framework – Part 3:

Patron format specifications

ISO/IEC 19794-1:2011, Information technology – Biometric data interchange formats – Part 1: Framework

ISO/IEC 19794-1:2011/Amd.1:2013, Conformance testing methodology

XML Schema Part 1: Structures Second Edition, W3C Recommendation, 28 October 2004, http:// www .w3

.org/ TR/ xmlschema -1/

XML Schema Part 2: Datatypes Second Edition, W3C Recommendation, 28 October 2004, http:// www

.w3 .org/ TR/ xmlschema -2/
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/IEC 19794-1:2011 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia available at http:// www .electropedia .org/ ;
— ISO Online Browsing Platform available at http:// www .iso .org/ obp.
4.1
channel

data item (captured, intermediate, or processed) recorded in form of a time series

EXAMPLE pen tip position x and y coordinates, pen tip force, pen tilt along the x and y axes, pen azimuth, pen

elevation, pen rotation
4.2
compression

process that reduces the size of a digital file with or without loss of information

Note 1 to entry: The compression format defined in Clause 10 includes data compressed by lossless compression

schemes.
4.3
pen azimuth

angle measured clockwise from the positive y axis to the perpendicular projection of the pen onto the

writing plane
Note 1 to entry: The pen azimuth may range from 0° to 360°.
4.4
pen-down event
event from which on the pen tip is touching the writing plane
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ISO/IEC DIS 19794-7:2020(E)
4.5
pen elevation

angle between the perpendicular projection of the pen onto the writing plane and the pen

Note 1 to entry: The pen elevation may range from 0° to 90°.
4.6
pen rotation

angle of the rotation of the pen about its longitudinal axis measured counter-clockwise from a device-

specific rotational reference position
Note 1 to entry: The pen rotation may range from 0° to 360°.
4.7
pen tilt along the x axis

angle measured clockwise from the positive z axis to the perpendicular projection of the pen onto the

x,z plane
Note 1 to entry: The pen tilt along the x axis may range from –90° to +90°.
4.8
pen tilt along the y axis

angle measured clockwise from the positive z axis to the perpendicular projection of the pen onto the

y,z plane
Note 1 to entry: The pen tilt along the y axis may range from –90° to +90°.
4.9
pen-up event

event from which on the pen tip is not touching the writing plane, after a pen-down event

4.10
sampling rate

number of samples per second (or per other unit) taken from a continuous signal to make a discrete signal

4.11
signature/sign representation
data recorded from a single signature/sign
4.12
X jitter

sample standard deviation of at least 100 x coordinate samples from a stationary pen

4.13
Y jitter

sample standard deviation of at least 100 y coordinate samples from a stationary pen

4.14
X pixel density

number of dots per millimetre that the capture device resolves in the x (horizontal) direction

4.15
Y pixel density

number of dots per millimetre that the capture device resolves in the y (vertical) direction

4 Abbreviated terms
lsb least significant bit
msb most significant bit
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ISO/IEC DIS 19794-7:2020(E)
5 Conformance

A binary biometric data record conforms to this document if it satisfies the format requirements with

respect to its structure, with respect to relations among its fields, and with respect to relations between

its fields and the underlying input that are specified within Clauses 6 to 10 of this document.

An XML document conforms to this document if it satisfies the format requirements with respect to its

structure, relations among its fields, and relations between its fields and the underlying input that are

specified within Annex E.

Biometric data interchange format conformance tests conform to this document if they satisfy all of the

normative requirements set forth in Annex A. Specifically, all level-1, level-2, and level-3 tests shall use

the test assertions defined in Table A.2, Table A.3, and Table A.4 of Clause A.2 in conformity with the

concept and rules set in ISO/IEC 19794-1:2011/Amd.1:2013.

Implementations of this document tested according to the specified methodology shall be able to claim

conformance only to those biometric data record requirements specified in this document that are

tested by the test methods established by this methodology.

Implementations of this document do not necessarily need to conform to all possible aspects of this

document, but only to those requirements that are claimed to be supported by the implementation in

an implementation conformance statement (ICS), filled out in accordance with ISO/IEC 19794-1:2011/

Amd.1:2013 and Table A.1 of Clause A.1 of this document.
6 Conventions
6.1 Coordinate system

The coordinate system used to express the pen position shall be a three-dimensional Cartesian

coordinate system. The x axis shall be the horizontal axis of the writing plane, with x coordinates

increasing to the right. The y axis shall be the vertical axis of the writing plane, with y coordinates

increasing upwards. The z axis shall be the axis perpendicular to the writing plane, with z coordinates

increasing upwards out of the writing plane starting from 0. For an illustration see Figure 1.

Figure 1 — Coordinate system

NOTE The origin of x and y coordinates is not specified here. Depending on the used technology, it may be, for

instance, in the centre of the writing pad, at its lower left corner, or at the pen position at the first pen-down event.

6.2 Octet and bit order

The more significant bytes of any multi-byte quantity are stored at lower addresses in memory than

(and are transmitted before) less significant bytes.

Within a byte, the bits are numbered from 8 to 1, where bit 8 is the ‘most significant bit’ (msb) and bit 1

the ‘least significant bit’ (lsb).
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ISO/IEC DIS 19794-7:2020(E)
6.3 Registered format type identifiers

The data records specified in this document may be embedded in a CBEFF- (ISO/IEC 19785-1) compliant

biometric information record (BIR). This clause lists the BDB (biometric data block) format owner

identifier and the BDB format type identifiers that shall be used if embedded in a CBEFF BIR. These

identifiers are registered with IBIA, the CBEFF Registration authority (see ISO/IEC 19785-2).

The format owner of the formats defined in ISO/IEC 19794 is ISO/IEC JTC 1/SC 37. The format owner

identifier is 257 (0101 ). Table 1 lists the format type identifiers for the formats defined in this

Hex
document.
Table 1 — Format type identifiers
CBEFF BDB format Short name Full object identifier
type identifier

14 (000e ) signature-sign-time- {iso(1) registration-authority(1) cbeff(19785) biometric-organ-

Hex
series-full ization(0) jtc1-sc37(257) bdbs(0) signature-sign-time-series-
full(14)}

15 (000f ) signature-sign-time- {iso(1) registration-authority(1) cbeff(19785) biometric-organi-

Hex
series-compact zation(0) jtc1-sc37(257) bdbs(0) signature-sign-time-series-com-
pact(15)}

30 (001e ) signature-sign-time- {iso(1) registration-authority(1) cbeff(19785) biometric-organi-

Hex

series-compression zation(0) jtc1-sc37(257) bdbs(0) signature-sign-time-series-com-

pression(30)}

NOTE 1 The format type identifier for the full format defined in this edition of ISO/IEC 19794-7 is the same

as the one for the full format defined in ISO/IEC 19794-7:2007. An indication of which version of the full format

applies can be determined from the version number included in the general header.

NOTE 2 The compact format defined in this edition of ISO/IEC 19794-7 is the same as the one defined in

ISO/IEC 19794-7:2007. Hence, the format type identifier for the compact format defined in this edition of

ISO/IEC 19794-7 is also the same as the one for the compact format defined in ISO/IEC 19794-7:2007.

7 Channels
7.1 General

Table 2 lists the channel names and their meanings. Signature/sign time series data captured with

different capture devices or used in different applications may contain data from different channels.

Either the T channel or the DT channel shall be present, or uniform sampling (constant time difference

between adjacent sample points) shall be indicated (see 7.6). Inclusion of at least one other channel is

mandatory.
Table 1 — – Channels
Channel name Description
X x coordinate (horizontal pen position)
Y y coordinate (vertical pen position)
Z z coordinate (height of pen above the writing plane)
VX velocity in x direction
VY velocity in y direction
AX acceleration in x direction
AY acceleration in y direction
T time
DT time difference
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ISO/IEC DIS 19794-7:2020(E)
Table 1 (continued)
Channel name Description
F pen tip force
S pen tip switch state (touching/not touching the writing plane)
TX pen tilt along the x axis
TY pen tilt along the y axis
A pen azimuth
E pen elevation
R pen rotation
7.2 Pen tip position channels: X, Y, Z

There are three channels defined for recording pen tip position data in the three-dimensional space.

The X channel is for recording the x coordinate of the projection of the pen tip on the writing plane. The

Y channel is for recording the y coordinate of the projection of the pen tip on the writing plane. The Z

channel is for recording the height of the pen tip above the writing plane.

The unit of measurement is millimetres (mm). To restore the actual values, the integer values given

in the record body are to be divided by a scaling value given in the channel description. By choosing

appropriate scaling values, different degrees of accuracy can be expressed.
7.3 Pen tip velocity channels: VX, VY

The VX channel is for recording the pen tip velocity along the x axis. The VY channel is for recording the

pen tip velocity along the y axis.

The unit of measurement is millimetres per second (mm/s). To restore the actual values, the integer

values given in the record body are to be divided by a scaling value given in the channel description. By

choosing appropriate scaling values, different degrees of accuracy can be expressed.

7.4 Pen tip acceleration channels: AX, AY

The AX channel is for recording the pen tip acceleration along the x axis. The AY channel is for recording

the pen tip acceleration along the y axis.

The unit of measurement is millimetres per square second (mm/s ). To restore the actual values,

the integer values given in the record body are to be divided by a scaling value given in the channel

description. By choosing appropriate scaling values, di
...