ISO/IEC TR 24485:2022

TECHNICAL ISO/IEC TR
REPORT 24485
First edition
2022-10
Information security, cybersecurity
and privacy protection — Security
techniques — Security properties and
best practices for test and evaluation
of white box cryptography
Sécurité de l’information, cybersécurité et protection de la vie
privée — Techniques de sécurité — Propriétés de sécurité et bonnes
pratiques pour les essais et l'évaluation de la cryptographie en boîte
blanche
Reference number
© ISO/IEC 2022
© ISO/IEC 2022
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© ISO/IEC 2022 – All rights reserved

Contents Page
Foreword .v
Introduction . vi
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 1
3 Terms and definitions . 1
4 S ecurity properties of white box cryptography . 2
4.1 I mplementation of a white box cryptography . 2
4.1.1 General . 2
4.1.2 Description of a WBC . 2
4.1.3 Adherence between WBC code and the device hosting it . 3
4.2 W BC attack path(s) . 3
4.2.1 General . 3
4.2.2 D e-embedding of code (code lifting) . 3
4.2.3 D evice analysis . 4
4.2.4 C ode analysis . 4
4.3 W BC usages . 4
4.3.1 G eneral . 4
4.3.2 S ymmetric encryption . 5
4.3.3 Asymmetric encryption / signature . 5
4.3.4 K eyed hash function . 5
4.3.5 Customized cryptographic algorithm . 5
4.4 S ecurity properties. 5
4.4.1 General . 5
4.4.2 S ecrecy of the key . 5
4.4.3 Difficulty to attack diversified instance. 6
4.4.4 D ifficulty to lift the code . 6
4.4.5 D ifficulty to reverse-engineer the binary / obfuscation code . 6
5 B est practices for WBC . 7
5 .1 Te s t s c ond it ion. 7
5.1.1 G eneral . 7
5.1.2 WBC under source code version . 7
5.1.3 W BC under compiled code version . 7
5.1.4 Best practices for testing . 7
5.2 S ecurity tests . 7
5.2.1 G eneral . 7
5.2.2 T esting the key secrecy . 7
5.2.3 T esting the difficulty to attack diversified instances . 7
5.2.4 T esting the difficulty to lift the code . 8
5.2.5 T esting the difficulty to reverse-engineer the binary / obfuscation code . 8
6 B est practices for WBC . 8
6.1 General . 8
6.2 C ore analyses . 8
6.2.1 G eneral . 8
6.2.2 C ryptanalytic analysis of tables . 8
6.2.3 S ide-channel analysis on WBC . 8
6.2.4 F ault injection analysis on WBC . 9
6.2.5 E valuation involving combined techniques . 9
6.3 A nalysis aiming at circumventing access to the plain WBC protection . 9
6.3.1 G eneral . 9
6.3.2 R everse-engineering of the binary code . 9
6.3.3 Space hardness evaluation . 9
Annex A (informative) Design of white-boxing-friendly cryptographic algorithms .10
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Bibliography .11
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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
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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
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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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This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 27, Information security, cybersecurity and privacy protection.
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
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Introduction
The white box cryptography (WBC) is a specific implementation method for cryptographic algorithms
where the secret key and the algorithm are entangled, so that the user can freely stimulate the latter.
However, the secret key is deeply engraved in the implementation, such that it is hard to extract and is
unambiguous. Furthermore, it is also difficult to update the WBC implementation in order to change
the key.
WBC is typically used for implementation when secure cryptographic module functionality (such as
a tamper-resistance device or a physically unclonable function) is unavailable for the protection of
secrets.
Business cases include DRM (digital right management) and HCE (host card emulation), in the contexts
of media protection and payment applications. WBC implementations are widely deployed on mobile
devices, where the cryptographic implementation is provided over the top.
The purpose of this document is to provide best practices on security assurance and to facilitate
users to assess the security level of several WBC implementations. It is important to share common
information and best practices about test and evaluation of WBC security.
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