ISO/IEC 19794-7:2021
(Main)Information technology — Biometric data interchange formats — Part 7: Signature/sign time series data
Information technology — Biometric data interchange formats — Part 7: Signature/sign time series data
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 can 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 can 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) and semantic test assertions (type A level 3 as defined in ISO/IEC 19794-1). 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); or — tests of conformance of systems that do not produce data records claimed to conform to the requirements of this document.
Technologies de l'information — Formats d'échange de données biométriques — Partie 7: Données de série chronologique de signature/signe
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INTERNATIONAL ISO/IEC
STANDARD 19794-7
Third edition
2021-10
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
Reference number
ISO/IEC 19794-7:2021(E)
© ISO/IEC 2021
---------------------- Page: 1 ----------------------
ISO/IEC 19794-7:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
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ISO/IEC 19794-7:2021(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 . 5
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 . 7
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 organization . 8
8.2 General header . 11
8.2.1 Structure . 11
8.2.2 Format identifier . 11
8.2.3 Version number . 11
8.2.4 Length of the data record . 11
8.2.5 Number of representations . 11
8.2.6 Certification flag . 11
8.3 Record body . 12
8.3.1 Structure .12
8.3.2 Representation header .12
8.3.3 Representation body . 17
9 Binary compact format .17
9.1 Record organization . 17
9.2 Comparison algorithm parameters template . 18
9.2.1 Structure . 18
9.2.2 Minimum and maximum number of sample points . 18
9.2.3 Channel descriptions . 19
9.3 Embedment in a CBEFF data structure . 20
9.4 Record body . 20
10 Binary compression format .20
10.1 Record organization . 20
10.2 General header . 21
10.3 Record body . 21
10.3.1 Structure . 21
10.3.2 Representation header . 21
10.3.3 Representation body . 24
11 XML encoding .25
Annex A (normative) Conformance testing methodology .26
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ISO/IEC 19794-7:2021(E)
Annex B (informative) Best practices — Data acquisition .71
Annex C (informative) ASN.1 specification of the binary compact format .72
Annex D (informative) Binary signature/sign encoding examples .75
Annex E (normative) XML schema definition .77
Annex F (informative) XML signature/sign encoding example .81
Bibliography .84
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ISO/IEC 19794-7:2021(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.
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 or
www.iec.ch/members_experts/refdocs).
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) or the IEC
list of patent declarations received (see patents.iec.ch).
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. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint 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. It also incorporates the Amendment ISO/IEC 19794-7:2014/Amd 1:2015.
The main changes 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 and IEC websites.
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 and
www.iec.ch/national-committees.
v
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INTERNATIONAL STANDARD ISO/IEC 19794-7:2021(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 can 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 can 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) and semantic test assertions (type A level 3 as defined in ISO/IEC
19794-1).
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); or
— 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 documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
1
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ISO/IEC 19794-7:2021(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 19794-1, Information technology — Biometric data interchange formats — Part 1: Framework
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19794-1 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
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-axis (3.7), pen tilt along the
y-axis (3.8), pen azimuth (3.3), pen elevation (3.5), pen rotation (3.6).
3.2
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.
3.3
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°.
3.4
pen-down event
event from which on the pen tip is touching the writing plane
3.5
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°.
3.6
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°.
3.7
pen tilt along the x-axis
angle measured clockwise from the positive z-axis to the perpendicular projection of the pen onto the
xz plane
Note 1 to entry: The pen tilt along the x-axis may range from –90° to +90°.
2
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ISO/IEC 19794-7:2021(E)
3.8
pen tilt along the y-axis
angle measured clockwise from the positive z-axis to the perpendicular projection of the pen onto the
yz plane
Note 1 to entry: The pen tilt along the y-axis may range from –90° to +90°.
3.9
pen-up event
event from which on the pen tip is not touching the writing plane, after a pen-down event (3.4)
3.10
sampling rate
number of samples per second (or per another unit) taken from a continuous signal to make a discrete
signal
3.11
signature/sign representation
data recorded from a single signature/sign
3.12
x jitter
sample standard deviation of at least 100 x-coordinate samples from a stationary pen
3.13
y jitter
sample standard deviation of at least 100 y-coordinate samples from a stationary pen
3.14
x pixel density
number of dots per millimetre that the capture device resolves in the x (horizontal) direction
3.15
y pixel density
number of dots per millimetre that the capture device resolves in the y (vertical) direction
4 Abbreviated terms
ASCII American Standard Code for Information Interchange
BDB biometric data block
BDIR biometric data interchange record
BHT biometric header template
BIR biometric information record
BIT biometric information template
CBEFF Common Biometric Exchange Formats Framework
IBIA International Biometrics & Identification Association
ICS implementation conformance statement
lsb least significant bit
msb most significant bit
3
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ISO/IEC 19794-7:2021(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 this document in conformity with
the concept and rules set out in ISO/IEC 19794-1.
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 are not necessarily required 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 and
Table 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.
Key
P writing plane
Figure 1 — Coordinate system
NOTE The origin of x and y-coordinates is not specified here. Depending on the used technology, it can 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.
4
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ISO/IEC 19794-7:2021(E)
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).
6.3 Registered format type identifiers
The data records specified in this document may be embedded in a CBEFF-compliant biometric
information record (BIR) (see ISO/IEC 19785-1). This subclause 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 the ISO/IEC 19794 series 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)}
38 (0026 ) {iso(1) registration-authority(1) cbeff(19785) biometric-organ-
Hex
XML-signature-sign-
ization(0) jtc1-sc37(257) bdbs(0) XML-signature-sign-time-se-
time-series
ries(38)}
NOTE 1 The format type identifier for the full format defined in this document (ISO/IEC 19794-7:2021) 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 document (ISO/IEC 19794-7:2021) 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.
Annex B provides recommendations for ensuring the quality of signature/sign time series data.
5
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ISO/IEC 19794-7:2021(E)
Table 2 — 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
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.
2
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, different degrees of accuracy can be expressed.
7.5 Time channel: T
The T channel is for recording the time elapsed since the first sample.
6
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ISO/IEC 19794-7:2021(E)
The unit of measurement is seconds (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.
7.6 Time difference channel: DT
The DT channel is for recording the time elapsed since the previous sample point.
The unit of measurem
...
INTERNATIONAL ISO/IEC
STANDARD 19794-7
Third edition
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
PROOF/ÉPREUVE
Reference number
ISO/IEC 19794-7:2021(E)
©
ISO/IEC 2021
---------------------- Page: 1 ----------------------
ISO/IEC 19794-7:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO/IEC 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 19794-7:2021(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 . 5
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 . 7
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 organization . 8
8.2 General header .11
8.2.1 Structure .11
8.2.2 Format identifier .11
8.2.3 Version number .11
8.2.4 Length of the data record .11
8.2.5 Number of representations .11
8.2.6 Certification flag .11
8.3 Record body .12
8.3.1 Structure .12
8.3.2 Representation header .12
8.3.3 Representation body .17
9 Binary compact format .17
9.1 Record organization .17
9.2 Comparison algorithm parameters template .18
9.2.1 Structure .18
9.2.2 Minimum and maximum number of sample points .18
9.2.3 Channel descriptions . .19
9.3 Embedment in a CBEFF data structure .20
9.4 Record body .20
10 Binary compression format .20
10.1 Record organization .20
10.2 General header .21
10.3 Record body .21
10.3.1 Structure .21
10.3.2 Representation header .21
10.3.3 Representation body .24
11 XML encoding .25
Annex A (normative) Conformance testing methodology .26
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ISO/IEC 19794-7:2021(E)
Annex B (informative) Best practices — Data acquisition .71
Annex C (informative) ASN.1 specification of the binary compact format .72
Annex D (informative) Binary signature/sign encoding examples .75
Annex E (normative) XML schema definition .77
Annex F (informative) XML signature/sign encoding example .81
Bibliography .84
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ISO/IEC 19794-7:2021(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.
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 or www .iec .ch/ members
_experts/ refdocs).
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) or the IEC
list of patent declarations received (see patents.iec.ch).
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. In the IEC, see www .iec .ch/ understanding -standards.
This document was prepared by Joint 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. It also incorporates the Amendment ISO/IEC 19794-7:2014/Amd 1:2015 and the
Technical Corrigendum ISO/IEC 9075-14:2016/Cor 1:2019.
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 and IEC websites.
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 and www .iec .ch/ national
-committees.
© ISO/IEC 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO/IEC 19794-7:2021(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 can 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 can 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) and semantic test assertions (type A level 3 as defined in
ISO/IEC 19794-1).
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); or
— 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 documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 19794-7:2021(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 19794-1, Information technology — Biometric data interchange formats — Part 1: Framework
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19794-1 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
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-axis (3.7), pen tilt along the
y-axis (3.8), pen azimuth (3.3), pen elevation (3.5), pen rotation (3.6).
3.2
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.
3.3
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°.
3.4
pen-down event
event from which on the pen tip is touching the writing plane
3.5
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°.
3.6
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°.
3.7
pen tilt along the x-axis
angle measured clockwise from the positive z-axis to the perpendicular projection of the pen onto the
xz plane
Note 1 to entry: The pen tilt along the x-axis may range from –90° to +90°.
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3.8
pen tilt along the y-axis
angle measured clockwise from the positive z-axis to the perpendicular projection of the pen onto the
yz plane
Note 1 to entry: The pen tilt along the y-axis may range from –90° to +90°.
3.9
pen-up event
event from which on the pen tip is not touching the writing plane, after a pen-down event (3.4)
3.10
sampling rate
number of samples per second (or per another unit) taken from a continuous signal to make a discrete
signal
3.11
signature/sign representation
data recorded from a single signature/sign
3.12
x jitter
sample standard deviation of at least 100 x-coordinate samples from a stationary pen
3.13
y jitter
sample standard deviation of at least 100 y-coordinate samples from a stationary pen
3.14
x pixel density
number of dots per millimetre that the capture device resolves in the x (horizontal) direction
3.15
y pixel density
number of dots per millimetre that the capture device resolves in the y (vertical) direction
4 Abbreviated terms
ASCII American Standard Code for Information Interchange
BDB biometric data block
BDIR biometric data interchange record
BHT biometric header template
BIR biometric information record
BIT biometric information template
CBEFF common biometric exchange formats framework
IBIA International Biometrics & Identification Association
ICS implementation conformance statement
lsb least significant bit
msb most significant bit
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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 this document in conformity with
the concept and rules set out in ISO/IEC 19794-1.
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 are not necessarily required 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 and
Table 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.
Key
P writing plane
Figure 1 — Coordinate system
NOTE The origin of x and y-coordinates is not specified here. Depending on the used technology, it can 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.
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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).
6.3 Registered format type identifiers
The data records specified in this document may be embedded in a CBEFF-compliant biometric
information record (BIR) (see ISO/IEC 19785-1). This subclause 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 the ISO/IEC 19794 series 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 document (ISO/IEC 19794-7:2021) 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 document (ISO/IEC 19794-7:2021) 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.
Annex B provides recommendations for ensuring the quality of signature/sign time series data.
Table 2 — Channels
Channel name Description
X x-coordinate (horizontal pen position)
Y y-coordinate (vertical pen position)
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Table 2 (continued)
Channel name Description
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
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.
2
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, different degrees of accuracy can be expressed.
7.5 Time channel: T
The T channel is for recording the time elapsed since the first sample.
The unit of measurement is seconds (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.
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7.6 Time dif
...
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