Mobile financial services — Customer identification guidelines

This document provides guidelines for customer identification in mobile financial services (MFS), including: — a general framework of customer identification for MFS; — the multi-dimensional overall identity assurance level (AL) of an MFS customer and its evaluation criteria; — security and privacy considerations. This document also contains annexes which demonstrate how to apply the ALs in practice, through (e)KYC use cases in different regions, for example. This document is applicable to various kinds of MFS providers, including but not limited to commercial banks and third-party payment service providers. This document is applicable to identifying natural persons. Identifying legal entities, known as (e)KYB, is out of the scope of this document.

Services financiers mobiles — Lignes directrices relatives à l'identification des clients

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Status
Published
Publication Date
05-Jan-2023
Current Stage
6060 - International Standard published
Due Date
02-Sep-2023
Completion Date
06-Jan-2023
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INTERNATIONAL ISO
STANDARD 5158
First edition
2023-01
Mobile financial services — Customer
identification guidelines
Services financiers mobiles — Lignes directrices relatives à
l'identification des clients
Reference number
ISO 5158:2023(E)
© ISO 2023
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ISO 5158:2023(E)
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© ISO 2023

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© ISO 2023 – All rights reserved
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ISO 5158:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

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

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

3 Terms and definitions .................................................................................................................................................................................... 1

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

5 General framework of customer identification for MFS ............................................................................................ 4

5.1 Identity of an MFS customer ...................................................................................................................................................... 4

5.2 Identification of an MFS customer ........................................................................................................................................ 5

5.3 Assurance levels .................................................................................................................................................................................... 6

6 Evaluation of multi-dimension identity AL ............................................................................................................................. 7

6.1 Evaluation criteria for AL_U ....................................................................................................................................................... 7

6.2 Evaluation criteria for AL_E ....................................................................................................................................................... 7

6.2.1 General ........................................................................................................................................................................................ 7

6.2.2 Identity evidences used in MFS environment .......................................................................................... 8

6.2.3 Evaluation criteria of identity evidence ALs ............................................................................................. 9

6.3 Evaluation criteria for AL_P .................................................................................................................................................... 10

6.4 Evaluation criteria for AL_W .................................................................................................................................................. 11

6.5 Evaluation criteria for AL_R .................................................................................................................................................... 11

7 Security and privacy considerations ...........................................................................................................................................12

7.1 Personal data protection of customer information ............................................................................................12

7.1.1 General privacy issues ................................... .............................................................................................................12

7.1.2 Biometrics-related vulnerabilities and privacy issues .................................................................12

7.2 Device side security ........................................................................................................................................................................12

Annex A (informative) Security capabilities of mobile devices related to customer

identification.........................................................................................................................................................................................................14

Annex B (informative) Case study of (e)KYC practices ..................................................................................................................16

Bibliography .............................................................................................................................................................................................................................22

iii
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ISO 5158:2023(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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 ISO documents 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 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/TC 68, Financial services, Subcommittee SC 2,

Financial Services, security.

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.
© ISO 2023 – All rights reserved
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ISO 5158:2023(E)
Introduction

With the rapid penetration of mobile devices into every aspect of people’s daily lives, mobile financial

services (MFS) have emerged as a result of the convergence of financial industry and ICT technologies.

MFS provide people with convenient access to basic financial services, such as payments, and are

therefore a great attraction for financial inclusion.

Much effort has been made to use financial technologies (fintech) to reduce the cost and improve the

efficiency of financial services. “Electronic know your customer (eKYC)” is a typical example of such

fintech, and market demand is growing rapidly due to MFS. Traditional KYC procedures, which usually

require customers to visit a bank branch to enrol for financial services in person, are time-consuming,

inconvenient and not suitable for lightweight MFS. In contrast, eKYC can provide a more competitive

alternative, giving end users more convenient access to financial services and helping financial service

providers attract more users.

Customer identification is at the core of eKYC. A mobile device can provide access to a number of

information sources which can be used for customer identification, such as:
— text message;
— phone call;
— location-based services (LBS);
— microphone (voice print);
— camera (photo identity document, human face, motions);
— various sensors (fingerprint, motions);

— contact and contactless local interfaces (to external credential carriers); and

— internet connection (to third-party identity providers).

However, KYC requirements and practices, especially online or remote eKYC, vary widely in different

jurisdictions. The identity evidence collected through a mobile device and the identity established

based on this evidence can differ greatly in terms of trustworthiness and assurance. The industry needs

a commonly-agreed standard to guide it on how to choose proper customer identification solutions for

MFS according to different KYC requirements. This document establishes such a common standard by

defining assurance levels (ALs) for identity evidence and corresponding identities in the context of MFS.

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INTERNATIONAL STANDARD ISO 5158:2023(E)
Mobile financial services — Customer identification
guidelines
1 Scope

This document provides guidelines for customer identification in mobile financial services (MFS),

including:
— a general framework of customer identification for MFS;

— the multi-dimensional overall identity assurance level (AL) of an MFS customer and its evaluation

criteria;
— security and privacy considerations.

This document also contains annexes which demonstrate how to apply the ALs in practice, through (e)

KYC use cases in different regions, for example.

This document is applicable to various kinds of MFS providers, including but not limited to commercial

banks and third-party payment service providers.

This document is applicable to identifying natural persons. Identifying legal entities, known as (e)KYB,

is out of the scope 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.

ISO 12812-1, Core banking — Mobile financial services — Part 1: General framework

ISO/IEC 24760-1, IT Security and Privacy — A framework for identity management — Part 1: Terminology

and concepts
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12812-1, ISO/IEC 24760-1 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
assurance level

amount of assurance obtained according to the specific scale used by the assurance method

[SOURCE: ISO/IEC 19792:2009, 4.1.1, modified — Note 1 to entry removed.]
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ISO 5158:2023(E)
3.2
biometrics

automated recognition of individuals based on their behavioural and biological characteristics

[SOURCE: ISO/IEC 19784-1:2018, 4.17]
3.3
customer

person or business that has contracted with a mobile financial services provider (MFSP) in order to

use mobile financial services (MFS)

Note 1 to entry: Only customers who are natural persons are covered by this document.

[SOURCE: ISO 12812-1:2017, 3.12, modified — Note 1 to entry added.]
3.4
evidence issuer

identity information provider or identity information authority (3.7) which issues the identity evidence

3.5
identity
set of attributes related to an entity
Note 1 to entry: The entity is a natural person in this document.
[SOURCE: ISO/IEC 24760-1:2019, 3.1.2, modified — Notes to entry replaced.]
3.6
identity assurance level
IAL

parameter used to describe the amount of assurance in a subscriber’s identity (3.5) obtained by a

credential service provider

Note 1 to entry: IAL1 indicates that there is no requirement to link the applicant to a specific real-life identity.

Note 2 to entry: IAL2 indicates that evidence supports the real-world existence of the claimed identity and

verifies that the applicant is appropriately associated with this real-world identity.

Note 3 to entry: IAL3 requires physical presence.
[SOURCE: NIST SP -800 -63A: 2019, 2.2, modified.]
3.7
identity information authority
IIA

entity related to a particular domain responsible for the life cycle management of trusted identities,

which can make provable statements on the validity and/or correctness of one or more attribute values

in an identity (3.5)

Note 1 to entry: An identity information authority is typically associated with the domain, for instance the

domain of origin, in which the attributes, which the identity information authority can make assertions on, have

a particular significance.

Note 2 to entry: The activity of an identity information authority is usually subject to a policy on privacy

protection.

Note 3 to entry: An entity can combine the functions of identity information provider and identity information

authority.

[SOURCE: ISO/IEC 24760-1:2019, 3.3.3, modified — Definition and Note 2 to entry revised.]

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ISO 5158:2023(E)
4 Abbreviated terms
AI artificial intelligence
AL_E assurance level of existence
AL_IDx overall identity assurance level of customer x
AL_P assurance level of presence
AL_R assurance level of reachability
AL_U assurance level of uniqueness
AL_W assurance level of willingness
AML anti-money laundering
BR biometric reference
CDD customer due diligence
CRM customer relationship management
eKYC electronic know your customer
FAR false acceptance rate
FRR false rejection rate
IC integrated circuit
IIP identity information provider
KBV knowledge-based verification
KYC know your customer
LoIP level of identity proofing
MFS mobile financial services
MFSP mobile financial services provider
MNO mobile network operator
NPI natural person identifier
OTP one-time password
PII personal identifiable information
REE rich execution environment
SE secure element
TEE trusted execution environment
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ISO 5158:2023(E)
5 General framework of customer identification for MFS
5.1 Identity of an MFS customer

Identity is the representation of an entity (natural person) in the form of one or more information

elements (known as “attributes”) which allow the entity to be sufficiently distinguished within a

context.
The identity attributes can consist of something that:
— characterizes the entity, for example biometric characteristics;
— the entity chooses, for example an email address;

— the entity has been assigned, for example an identity number assigned by the national authority;

— constitutes other personal information associated with the entity (natural person), for example

geolocation.

The combination of all attributes of the entity (unlimited number) is called a “holistic identity”. In the

context of MFS, the identity of an MFS customer should be regarded as a “contextual identity”, which

consists of a limited set of attributes which are sufficient for verifying that the entity who is applying

for a service is the one who was enrolled previously, as depicted in Figure 1.
Key
a e c
MFS customer. MFS customer’s identity as of key reference .
b f d
MFS provider. MFS customer’s identity as of key reference .
c g b

IIP/IIA which can provide Attributes 1 to 5. MFS customer’s identity as of key reference .

IIP/IIA which can provide Attributes 4 to 7.
Figure 1 — Identity and attributes

A contextual identity, once established, should be able to be confirmed or verified using authentication

methods, such as something that the MFS customer possesses, knows, or is (inherence such as

biometrics). Identity authentication methods are out of the scope of this document.

The natural person identifier (NPI) and its data record, as defined in ISO 24366, is recommended as the

reference when the MFS providers select the set of attributes to identify their customers. An NPI issuer

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ISO 5158:2023(E)

can be regarded as an identity information provider (IIP) or an identity information authority (IIA),

depending on local regulations.

Local KYC and anti-money laundering (AML) regulations usually define several mandatory attributes

for initial identification of the financial customers. See Annex B for examples.

Depending on the nature of specific financial services, it is possible that additional identity attributes

will be needed, for example geolocation (home address or office address), employment status or

emergency contacts.
5.2 Identification of an MFS customer

Identification of a financial services customer, known as (e)KYC in the financial sector, includes identity

proofing, enrolment and continuous maintenance of the customer’s identity attributes required to

provide certain financial services. General concepts of identity proofing and enrolment can be found in

ISO/IEC TS 29003.

The identification process for an MFS customer should be composed of the following basic steps.

a) The MFS customer provides core verifiable attributes as required by the MFS provider and/or

provides eligible identity evidence to support the claimed attributes.

b) The MFS provider validates, by all possible means, the authenticity, validity and eligibility of the

identity attributes and evidence provided by the MFS customer.

c) The MFS provider verifies, by all possible means, the links between the MFS customer and the

provided identity attributes and evidence, as well as the willingness of the MFS customer to apply

for the specified services.

d) The MFS provider enrols the MFS customer after successful initial verification of required identity

attributes and continuously maintains (adding, removing or updating) the MFS customer’s identity

attributes according to the business and compliance requirements.

In step a), there are different ways to collect identity attributes, for example:

— self-claimed by the customer, for example:
— ask the customer to fill in a table (text attributes);
— ask the customer to upload a selfie (facial image);
— retrieval from an identity document presented by the customer, for example:

— ask the customer to upload a photo of an identity card (usually equipment with certain anti-

forgery measures);

— ask the customer to present a digital identity document containing certain identity attributes

(usually with a digital signature);
— retrieval from a database, for example:
— retrieve identity attributes from a specialized third-party IIP;
— retrieve identity attributes from a domain-specific IIA.

NOTE 1 Additional information can be requested from the customer in order to allow the retrieval of attributes

from a database and to link the relevant attributes, for instance by pressing a finger on a fingerprint sensor (e.g.

fingerprint database on VISA information systems or the Indian Aadhaar eKYC use case; see Annex B).

In step b) and step c), the MFS provider should, by all possible means, confirm the following aspects:

— the authenticity, validity and eligibility of the identity attributes and evidence provided by the MFS

customer;
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ISO 5158:2023(E)

— the links between the MFS customer and the provided identity attributes and evidence;

— the willingness of the MFS customer to apply for the specified services.

Depending on the different ways to confirm these three aspects, the MFS provider can achieve different

levels of assurance in the identity of an MFS customer.

NOTE 2 Although the customer is aiming to access some MFS, the identity proofing process can occur partially,

entirely or not at all on mobile devices.
5.3 Assurance levels

The overall assurance level of an MFS customer’s identity should be defined as a multi-dimensional

vector. In particular, this document defines the following dimensions.
— Assurance on uniqueness: AL_U

How confident the MFS provider can be that the customer identity is unique in the specific MFS

provider’s domain.
— Assurance on existence: AL_E

How confident the MFS provider can be that the customer identity corresponds to a real-life subject,

i.e. the genuineness of the identity attributes and/or evidence.
— Assurance on presence: AL_P

How confident the MFS provider can be of the links between the present MFS customer and the

provided identity attributes and/or evidence.
— Assurance on willingness by consent: AL_W

How confident the MFS provider can be of the willingness of the MFS customer to apply for the

specified services.
— Assurance on reachability: AL_R

How confident the MFS provider can be that the customer can be contacted when necessary. This

is an additional criterion, not directly bound to the identity but used to manage the overall risk

related to the MFS customer.

These dimensions may be tailored and other dimensions may be added according to the jurisdictional

AML or related requirements. The willingness and reachability dimensions are included as example

dimensions to group some identity attributes which are not directly used to identify a customer, but

which are indispensable for the MFS provider to make business decisions.

The overall identity assurance level of an MFS customer, “x”, should be noted as follows:

AL_IDx = (AL_U, AL_E, AL_P, AL_W, AL_R, …)

Each dimension should be evaluated against the criteria which are commonly agreed upon and

recognized within the MFS provider’s domain. Details are provided in Clause 6.

NOTE AL_IDx is intended as a vector, not a simple score. But if the MFS provider needs to calculate a simple

score, the weighting of each dimension can be defined according to its KYC policy and a weighted sum can be

calculated and assigned to AL_IDx.

It is recommended that the AL value of each dimension ranges from 0 to 1, both included. But other

kinds of value domain are also acceptable according to the needs of the MFS providers.

Based on the different identity ALs, the MFS provider can grant differentiated services to its customers.

Examples are provided in Annex B.
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ISO 5158:2023(E)

As part of the customer due diligence (CDD) requirements, the MFS provider can increase or decrease

the AL(s) in one dimension or more for a specific customer over time, for example when the contact

information is no longer valid, the AL_R is decreased. The MFS provider can also ask the customer to

increase the AL(s) in one dimension or more if the customer wants to apply for a service which requires

higher AL(s).
6 Evaluation of multi-dimension identity AL
6.1 Evaluation criteria for AL_U

Table 1 shows the recommended evaluation criteria for AL_U. A brief risk analysis is also provided.

Table 1 — Recommended evaluation criteria and risk analysis for AL_U
AL_U value Description Criteria Risk analysis

0 No assurance of The MFS customer does not need to enrol When a security incident arises

uniqueness or log in to access a service, for example with a customer, it cannot be

to browse the real-time foreign exchange traced back to a particular
rates. customer.

(0, 1) Ambiguous The MFS customer needs to provide When a security incident arises

certain identity attribute(s), such as with a customer, it cannot be
age or geolocation, to access a service. traced back to a particular
customer but can be traced
back to a subset of possible
customers, for instance when
first name and surname have
been recorded without
additional identifying attributes.
1 Uniqueness as- The MFS customer needs to provide None.
sured adequate identity attribute(s) so that
they can be uniquely identified by the
MFS provider in the specific MFS
provider’s domain by:
— a single attribute (e.g. a national
identity number or unique biometric
characteristic); or
— an adequate set of attributes (e.g. a
combination of name, date of birth and
facial image).
6.2 Evaluation criteria for AL_E
6.2.1 General
The recommended evaluation criteria for AL_E is as follows.

Step 1: Determine the AL of an identity evidence according to Table 2 by the overall AL or eligibility of

the evidence issuer, and the security and risk-control measures which are leveraged during evidence

validation:
— physical evidence: anti-forgery measures;

— digital evidence and online IIP database: security measures such as digital signature.

More details are provided in 6.2.2 and 6.2.3.
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ISO 5158:2023(E)

Step 2: Determine the AL of an identity attribute by the maximum AL, as in Formula (1), or a weighted

sum of the ALs of its supporting identity evidence(s), as in Formula (2):
LL=…max(),,L , L (1)
ae1e2 en
where
L is the AL of the identity attribute, a;
L is the AL of the first identity evidence to support this attribute;
L is the AL of the second identity evidence to support this attribute;
L is the AL of the last identity evidence to support this attribute.
1 n
L =×wL (2)
ae∑ ii
i=1
where
L is the AL of the identity attribute, a;
n is the total amount of collected evidence to support this attribute;
L is the AL of the ith identity evidence to support this attribute;

w is the weight assigned to the ith identity evidence to support this attribute, with the

constraint that w = 1 and w ∈[]01, ;
∑ i i
i=1

Step 3: Determine the AL of customer existence by the minimum AL of its mandatory attributes, as in

Formula (3):
LL=…min ,,L , L (3)
Ea12aam
where
L is the AL of customer existence (AL_E);
L is the AL of the first mandatory attribute;
L is the AL of the second mandatory attribute;
L is the AL of the last mandatory attribute.
6.2.2 Identity evidences used in MFS environment
Identity evidence used in MFS environments can be classified as follows.

— Digitalized physical evidence, for example a photo of a driving licence (containing a facial image), a

photo of a bank card.

— Digital identity, for example a digital certificate containing the owner’s identity information and

related attributes (e.g. fingerprints) held on a physical token such as an identity integrated circuit

(IC) card, which can generate a digital signature for identification, or in software.

— Online identity information database, for example an interface to access the mobile network

operator (MNO) customer relationship management (CRM) database or an interface to access a

governmental IIA.
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ISO 5158:2023(E)

In particular, biometrics are very commonly used as part of the identity evidence. There are three ways

that a person can be identified using biometrics:

— identification based on the biometric information on the facial image in an identity document;

— identification based on biometric information stored in the IC chip of an identity document;

— identification based on biometric information stored in a central database.
6.2.3 Evaluation criteria of identity evidence ALs

Table 2 shows the recommended evaluation criteria for identity evidence. A brief risk analysis is also

provided.

Table 2 — Recommended evaluation criteria and risk analysis for identity evidence ALs

Evidence AL Description Criteria Risk analysis
value

0 Evidence is not The evidence is revoked, or the evidence issuer is: The evidence cannot

dependable be linked to a real life
— not eligible according to the MFS provider’s
individual.
KYC policies; or
— evaluated as IAL 1 (NIST), LoIP 1
(ISO/IEC TS 29003) or equivalent.
...

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