ISO/IEC 20085-2:2020

INTERNATIONAL ISO/IEC
STANDARD 20085-2
First edition
2020-03
IT Security techniques — Test tool
requirements and test tool calibration
methods for use in testing non-
invasive attack mitigation techniques
in cryptographic modules —
Part 2:
Test calibration methods and
apparatus
Techniques de sécurité IT — Exigences de l'outil de test et méthodes
d'étalonnage de l'outil de test utilisées pour tester les techniques
d'atténuation des attaques non invasives dans les modules
cryptographiques —
Partie 2: Méthodes et appareillage d'étalonnage et d'essai
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
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ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Test tools . 2
5.1 Tools and analysis . 2
5.2 Determining the test result . 2
5.3 Measurement tool . 2
5.4 Analysis tool . 2
6 Calibration methods . 3
6.1 Aspects . 3
6.2 Introduction to calibration procedure . 3
6.2.1 General knowledge of calibration procedure . 3
6.2.2 Accuracy of test tools . 3
6.2.3 Measurement tool . 4
6.2.4 Calibration principle . 4
6.3 Calibration procedure . 4
6.3.1 General. 4
6.3.2 Point of measurement . 5
6.3.3 Parameter adjustment . 5
6.4 Calibration metrics . 5
7 Artefact . 6
7.1 General . 6
7.2 Side-channel analysis . 6
7.3 Open target . 6
7.3.1 General. 6
7.3.2 General specification . 6
7.3.3 Example specification . 6
7.4 Closed target . 6
Annex A (informative) Cryptographic algorithms and calibration metrics .7
Annex B (informative) Countermeasures to tune the security strength .9
Annex C (informative) An example artefact implementation — A hardware security module
emulated with an FPGA .11
Annex D (informative) An example artefact implementation — A microcontroller .13
Annex E (informative) An example artefact implementation — Signal generator .15
Bibliography .16
© ISO/IEC 2020 – All rights reserved iii

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).
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
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list of patent declarations received (see http:// patents .iec .ch).
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iso/ foreword .html.
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.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 27, Information security, cybersecurity and privacy protection.
A list of all parts in the ISO/IEC 20085 series can be found on the ISO website.
iv © ISO/IEC 2020 – All rights reserved

Introduction
Cryptographic modules provide cryptographic services and protect critical security parameters.
Protection of critical security parameters can either be logical, physical, or both. Information such as
knowledge of critical security parameters can leak out of the cryptographic module during operation,
if the module is not designed to mitigate such leakage. Without mitigation, a malevolent attacker can
record available side-channel leakage. This leakage is a physical quantity related to the critical security
parameters and can be analysed in a manner to extract information about those parameters. Such
analysis is passive, in that it simply collects the side-channel leakage measurements which can be freely
acquired with an apparatus. Notice that the measurement tool can, as well, be adaptively controlled.
This kind of extraction and analysis is referred to as non-invasive. Techniques that allow the extraction
of critical security parameters out of this non-invasive leakage is termed an attack on the module.
Non-invasive attack testing is a method to determine whether the leakage of a cryptographic module
can be exploited to extract critical security parameters. A non-invasive attack test tool returns a pass
status if the cryptographic module leakage is determined to be of a minimal amount which may prevent
disclosure of critical security parameters. Otherwise, it returns a fail status.
This document focuses on the calibration of the side-channel measurement tool. This calibration
process enables two measurement tools to record measurements equally usable in terms of side
channel analysis. Calibration is presented as the combination of two techniques:
a) definition of a method for calibration;
b) requirement of a reference cryptographic module (called an artefact) to define a clear threshold
between test results, in terms of fail or pass.
Both aspects are covered in this document.
© ISO/IEC 2020 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 20085-2:2020(E)
IT Security techniques — Test tool requirements and test
tool calibration methods for use in testing non-invasive
attack mitigation techniques in cryptographic modules —
Part 2:
Test calibration methods and apparatus
1 Scope
This document specifies the test calibration methods and apparatus used when calibrating test tools
for cryptographic modules under ISO/IEC 19790 and ISO/IEC 24759 against the test metrics defined in
ISO/IEC 17825 for mitigation of non-invasive attack classes.
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.
ISO/IEC 17825, Information technology — Security techniques — Testing methods for the mitigation of
non-invasive attack classes against cryptographic modules
ISO/IEC 19790, Information technology — Security techniques — Security requirements for
cryptographic modules
ISO/IEC 20085-1, IT Security techniques — Test tool requirements and test tool calibration methods for
use in testing non-invasive attack mitigation techniques in cryptographic modules — Part 1: Test tools and
techniques
3 Terms and definitions
For the purposes of this document, the terms, definitions given in ISO/IEC 19790, ISO/IEC 17825,
ISO/IEC 20085-1, and the following apply.
ISO and IEC
...