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This white paper has been published by the World Economic Forum as a contribution to a project,
insight area or interaction. The findings, interpretations and conclusions expressed herein are a result of a collaborative process facilitated and endorsed by the World Economic Forum, but whose
results do not necessarily represent the views of the World Economic Forum, nor the entirety of its
Members, Partners or other stakeholders.

Contents
1. Foreword

4

2. Executive summary

5

3. Introduction

7

3.1 Background

7

3.2 Purpose and scope

8

3.3 KTDI principles and core technologies

8

4. KTDI: Solution overview

10

5. KTDI solution components: Capabilities and standards

14

5.1 Layer 1: DID networks

14

5.2 Wallets and agents

16

5.3 IT Infrastructure and supporting technologies

22

6. Pilot technology
6.1 Technology developments

23
23

7. Conclusion

24

8. Contributors

25

9. Endnotes

26

3

1. Foreword

In January 2018, the World Economic Forum introduced its Known Traveller Digital Identity (KTDI)
concept, an initiative co-designed by public- and private-sector partners that aims to anticipate
the challenges, and take advantage of the immense opportunities, that emerging technologies will
present in the cross-border movement of people. The KTDI concept seeks to address the changing
behaviours and expectations of travellers, the growing volume of global travellers, and the increasing
focus on risk-based security to promote more seamless and secure travel.
The KTDI concept relies upon a trusted, decentralized and interoperable identity platform enabled
through technologies including blockchain, biometrics, mobile devices and cryptography. The Forum
and its partners are currently piloting components of the KTDI concept in a real-life, cross-border
context between the Netherlands and Canada. The pilot is testing various elements of the KTDI
concept’s policies, processes and technologies to further enhance the concept and inform future pilots
and the development of best practices and standards in collaboration with international regulatory
and standards-setting bodies and industry. In future iterations, multiple pilots can run – potentially in
parallel and with different use cases, partners, technologies and geographies – to enrich the outcome
and scalability of the KTDI concept.
As the pilot is under way, this White Paper documents the standards, open specifications and
industry best practices that have shaped the initial pilot and that provide guiding principles for the
KTDI concept and any related future pilots towards the end-state vision of global interoperability. The
document references applicable standards, capabilities and functionalities that comparable solutions
should consider in order to interoperate with the KTDI concept.
This paper is the result of collaboration between the World Economic Forum, Accenture and our
partners to inspire active multistakeholder action in this fast-moving landscape. It serves two aims:
first, to inform ongoing initiatives and pilots to advance the convergence and harmonization of
global developments and, second, as a tool to compare and align KTDI and other complementary
approaches and technologies with the ambition to secure maximum interoperability and global
adoption. The Forum welcomes engagement from other organizations advancing secure and
seamless travel, and looks forward to further collaboration on this subject.

4

2. Executive summary

In January 2018, the World Economic Forum’s
Platform for Shaping the Future of Mobility
introduced its Known Traveller Digital Identity
(KTDI) concept, an initiative co-designed by
public- and private-sector partners that seeks
to anticipate the changing behaviours and
expectations of travellers, the growing volume of
global travellers, and the increasing focus on riskbased security to promote more seamless and
secure travel.
The Forum and its partners are currently piloting
components of the KTDI concept in a real-life,
cross-border context between the Netherlands
and Canada. The pilot’s lessons will help to
further enhance the KTDI concept and to inform
future pilots and the development of best
practices and standards in collaboration with
international regulatory and standards-setting
bodies and industry. In future iterations, multiple
pilots can run – potentially in parallel and with
different use cases, partners, technologies
and geographies – to enrich the outcome and
scalability of the KTDI concept.
This White Paper describes the technical
foundation of the KTDI concept and documents
the standards, open specifications and industry
best practices that have shaped the initial pilot
and that provide guiding principles for the KTDI
concept and any related future pilots.
The KTDI concept was designed to adhere to the
values and principles of decentralized identity,
including ownership and control of identity
attributes, privacy and disintermediation. As such,
the KTDI solution is built upon the decentralized
identity model, leveraging the emerging
World Wide Web Consortium (W3C) verifiable
credentials (VC) and decentralized identifier (DID)
standards. This model allows travellers to self-

manage digital identity attributes that are attested
to and provided by issuing authorities (both public
and private) so the individual may share them
through selective disclosure.
This paper focuses on describing the various
layers of the decentralized identity model and the
capabilities, standards and specifications that
apply to each and that have been leveraged to
build the KTDI solution. The layers are divided
into two categories of trust (cryptographic and
human) as follows (this paper does not cover
layer 4):

Cryptographic
trust
Human trust

Layer 1: DID Networks
Layer 2: DID Communication
Protocol
Layer 3: Credential Exchange
Layer 4: Governance
Frameworks

The intended audience for this paper includes
teams supporting chief information or
technology officers of organizations interested
in exploring the adoption of the KTDI concept
or complementary solutions. This paper is not
intended to cover specific details, lessons or
outcomes from the KTDI pilot that is currently
under implementation.
As emerging decentralized identity strategies and
technologies continue to develop, it is important
to consider alternative or complementary
technologies and approaches that may also
support KTDI’s core principles. The expected
advantages and disadvantages of every
technological choice must be thoroughly assessed
on a use case basis, considering legal, national
security, certification, risk and other requirements.

5

This paper outlines the ambition for KTDI to
provide the foundations for a globally accepted
decentralized identity ecosystem. Further
development and wider adoption depend on
maximizing data exchange interoperability
and federated trust, for which the best use of
international standards, open specifications and
industry best practices are essential. Success
will rest upon cooperation between world
governments, regulators, the aviation industry,
technology providers and other players to
establish global standards and specifications for
compliance by all stakeholders.
As the leading global platform for publicprivate cooperation, the Forum is committed
to strengthening the kind of multistakeholder
collaboration needed to achieve interoperability
in the new identity paradigm that continues to
unfold. The Forum invites interested stakeholders
to provide feedback and proposals for new pilots
or approaches to enhance or complement the
KTDI concept and further this goal.

6

The Pilot Group is working collaboratively to
test critical elements of the KTDI concept (i.e.
governance, privacy and security frameworks
and the technology) in a cross-border, real-life
environment.
The pilot’s lessons will help mature the KTDI
concept and assess the potential for its use
by additional stakeholders, such as other
governments, airlines and airports as well as
hotels, car rental companies, and other players
in the travel and tourism sector. In future
iterations of the KTDI concept, multiple pilots
can be run – potentially in parallel and with
different technologies – to enrich its outcome
and scalability.

3.2 Purpose and scope
From the outset, the KTDI concept was designed
with global interoperability as a core design
principle, with a view to maximizing the use
of open source technologies, open standards
and industry best practices (e.g. for security
and privacy) and avoiding vendor lock-in. This
paper presents a first step in efforts to continue
building upon the recommendations outlined in
the concept paper and to promote increased
multistakeholder collaboration and dialogue on
the path towards global interoperability.
Moreover, since 2018, the International Air
Transport Association (IATA) has advanced
its learnings on the One ID concept, and the
International Civil Aviation Organization (ICAO),
which is responsible for setting international
standards for aviation, including passport
issuance, has been developing specifications
for digital travel credentials. Through close
observance of and engagement with these
organizations, the KTDI concept continues to
evolve, such that this guidance document aims
to contribute to ongoing discussions for the
development, use and exchange of digital travel
credentials and interoperability.
This White Paper catalogues the most
important and relevant standards, technologies,
specifications and best practices that have been
leveraged to build the KTDI solution. Some of the
8

standards and specifications listed in this paper
come from various working groups aligned with
different organizations and may change over time.
That said, these working groups often have a
similar membership and many groups are making
efforts to collaborate. Care should be taken to
evaluate each standard and specification, and
identify any areas that are not complementary.
Further information on the KTDI concept is available
from the KTDI website2 and concept report.

3.3 KTDI principles and core
technologies
The KTDI concept was designed to adhere to the
values and principles of decentralized identity,
including ownership and control of identity
attributes, privacy and disintermediation. The
core enabling technologies selected for KTDI
support these values and are currently being
tested by the Pilot Group.
Decentralized identity is commonly referred to
as self-sovereign identity (SSI), a term used to
describe “the digital movement that recognizes
an individual should own and control their
identity without the intervening administrative
authorities”.3 Although it is an industry-accepted
term (also adopted by the European Union,4
among others), some maintain that self-managed
identity is a more appropriate term because a
self-issued identity claim has little value to many
relying parties. In the KTDI concept, the core
verifiable claim that will be used by travellers is
based on a government-issued credential derived
from the passport. As such, for the purposes
of this document, SSI refers to a decentralized
identity that is self-managed and that is based on
a government-issued verifiable credential.
As explained in Section 6 in more detail, a
blockchain-based platform was selected as the
key enabling technology for the KTDI concept
and pilot with the goal of better understanding
integration requirements between multiple
stakeholders in this industry. However,
decentralized identity management solutions
could be non-blockchain based and other
approaches could also be used.

As emerging decentralized identity strategies and
technologies continue to develop, it is important
to consider alternative or complementary
technologies and approaches that may also
support KTDI’s core principles. The expected
advantages and disadvantages of every
technological choice must be thoroughly assessed
on a use case basis, considering legal, national
security, certification, risk and other requirements.
Ongoing work in decentralized identity
management, including decentralized public key
infrastructure (DPKI), custodianship and zeroknowledge proofs (ZKP), must be assessed
and potentially tested in future pilots. Different
technology choices may result in diverse trust
frameworks that could be linked to co-exist as
part of an inter-federation model, thereby meeting
the varying yet overlapping requirements of
different stakeholders. Further collaboration is
needed to explore complementary approaches
for SSI to allow for maximum identity reuse and
global acceptance.

9

5. KTDI solution components:
Capabilities and standards

As shown in Table 2, the core of the solution can
be broken down into:
– Layer 1: DID networks
– Wallets and agents, covering:
– Layer 2: DIDComm protocol
– Layer 3: Credential exchange
– IT infrastructure and supporting technologies.
This section details the capabilities within each
layer as well as relevant standards (draft or
approved), open-specifications and related
industry guidance.
The wallet and agent structures sit across
layers 2 and 3 and provide for the peer-to-peer
communications at the heart of decentralized
identity. Due to their matrix nature, wallets and
agents are covered in this paper in detail, with
the capabilities per layer and per actor broken
out specifically.

14

5.1 Layer 1: DID networks
DID networks are split into the underlying
blockchain network and the decentralized
identity overlay.
5.1.1 Blockchain network
The capabilities required of the underlying
ledger are like any other decentralized ledger
technology platform. While the list in Table 3
is non-exhaustive, it provides an outline of the
capabilities expected.
These capabilities guided the search for
the standards that were relevant to this
implementation. The standards listed in Table
4 were accounted for and applied during the
design and execution.

6. Pilot technology

As previously mentioned, the KTDI pilot is still
under implementation and therefore the specific
standards and open specifications that have
been leveraged may be updated or changed
during the course of the pilot. However, the
technology platform has been chosen.
Hyperledger Indy12 was selected as the
decentralized identity platform for the KTDI pilot
solution. Indy is purpose-built for decentralized
identity, providing tools, libraries and reusable
components to create and use independent
digital identities rooted by blockchains so they
are interoperable across administrative domains,
applications and any other “silo”.
Hyperledger Indy meets the following functional
and non-functional programme requirements:
– Identity focused: it has pre-built identityrelated agents and libraries
– Standards focused: it is not a standard, but
it aims to align to and use industry accepted
standards
– Open source
– Stand-alone: it does not require membership
in a particular blockchain network
– Alignment with a private, permissioned
blockchain network model
– DID-focused logic
– Scalable.

6.1 Technology developments
It should be noted that some Hyperledger
Indy components are being migrated to
the Hyperledger Aries and Ursa projects to
modularize solution components to allow
for more tailored solutions and for individual
components to mature at different rates.
Hyperledger Aries will provide infrastructure for
blockchain-rooted, peer-to-peer interactions.
It includes a shared cryptographic wallet
(the secure storage technology, not the user
interface) for blockchain clients as well as
a communications protocol for off-ledger
interaction between those clients.
Hyperledger Aires uses the cryptographic
support provided by Hyperledger Ursa to provide
secure secret management and decentralized
key management functionality. Hyperledger Ursa
is a shared cryptographic library that enables
people and projects to avoid duplicating other
cryptographic work, potentially increasing
security in the process. The library would be an
opt-in repository for projects (and, potentially
contributors) to place and use cryptography.
Hyperledger Indy will continue supporting Aries
and Ursa as portions of the Indy libraries are
migrated into Aries core libraries, and IndyCrypto is being replaced with Ursa in Indy Node.
At this time, there is no reason to migrate the
KTDI pilot solution away from Hyperledger Indy.

23

7. Conclusion

This White Paper outlines the ambition for KTDI to provide the foundations for a globally accepted
decentralized identity ecosystem. Further development and wider adoption depend on maximizing
data exchange interoperability and federated trust, for which the best use of international standards
(existing and emerging), open specifications and industry best practices are essential. Success will rest
upon cooperation between world governments, regulators, the aviation industry, technology providers
and other players to establish global standards and specifications for compliance by all stakeholders.
The KTDI concept is not tied to a particular product, is modular, scalable and based on emerging
and existing international standards. The World Economic Forum will continue to engage additional
stakeholders to launch further pilots and explore new use cases, geographies and technology
approaches. Decision-makers may then combine the lessons learned from the pilots to provide the
optimum way ahead that maximizes flexibility and benefits, without constraining organizations or
nations to specific solutions.
Organizations seeking to test or develop the KTDI concept or complementary solutions should
become familiar with the core concepts of decentralized identity as well as the relevant standards and
technology approaches available. Stakeholders should also identify potential use cases, their scope,
and how the pilot would align with their long-term vision. The development of additional pilots will
require addressing practical considerations, including legal, cybersecurity, privacy and national security
requirements. National and international assurance models are still emerging for SSI solutions based on
blockchain technologies, and to date no countries have adopted such a model for cross-border travel.
The KTDI concept shows great potential for use beyond the travel industry, including applications
in healthcare, education, banking, humanitarian aid and other sectors. It will be critical to leverage
network effects by earning the trust of users, engaging more government entities and crowding in
more private parties to build the concept, continue to broaden the horizon and be at the forefront of
disruptive changes.
The Forum and its partners will also continue to conceptualize the appropriate governance frameworks
that would promote trust between ecosystem players and establish the premises to maximize
interoperability and global adoption in the travel sector and beyond. As some of the standards and
specifications catalogued in this White Paper continue to evolve, it is critical to monitor developments
as well as new technology approaches and innovations that may be leveraged. Ongoing collaboration
with international organizations like ICAO and IATA to develop and use digital travel credentials is also
crucial to ensure complementarity towards a common goal.
As the leading global platform for public-private cooperation, the Forum is committed to strengthening
the kind of multistakeholder collaboration needed to achieve interoperability in the new identity paradigm
that continues to unfold. The Forum invites interested stakeholders to provide feedback and proposals
for new pilots or approaches to enhance or complement the KTDI concept and further this goal.

24

8. Contributors
The World Economic Forum acknowledges the valuable contributions to this White Paper of our community
of stakeholders collaborating on the KTDI concept and pilot.

25

9. Endnotes
1.

World Economic Forum, The Known Traveller: Unlocking the potential of digital identity for secure and
seamless travel, 2018, http://www3.weforum.org/docs/WEF_The_Known_Traveller_Digital_Identity_
Concept.pdf.

2.
3.

World Economic Forum, Known Traveller Digital Identity [website], 2019, www.ktdi.org.
Sovrin, “What is self-sovereign Identity?”, 6 December 2018, https://sovrin.org/faq/what-is-selfsovereign-identity.

4.

European Economic and Social Committee, “European Self Sovereign identity framework”, 25 June
2019, https://www.eesc.europa.eu/en/news-media/presentations/european-self-sovereign-identityframework.

5.

Decentralized Identity Foundation, Our Focus [website], https://identity.foundation/#about.

6.

Hardman, Daniel, “Credential Revocation”, Hyperledger Indy, 2018, https://hyperledger-indy.
readthedocs.io/projects/hipe/en/latest/text/0011-cred-revocation/README.html.

7.

Sovrin, “Sovrin Glossary V3”, in Sovrin Governance Framework, 4 December 2019,
https://docs.google.com/document/d/1gfIz5TT0cNp2kxGMLFXr19x1uoZsruUe_0glHst2fZ8/
edit?pli=1#heading=h.851bm05lgtfu.

8.

GitHub, “Overview of DIDComm”, 11 August 2019, https://github.com/decentralized-identity/
DIDComm-js/blob/master/docs/README.md.

9.

W3C, “4.7 Proofs (Signatures)”, in Verifiable Credentials Data Model 1.0, 19 November 2019,
https://www.w3.org/TR/vc-data-model/#proofs-signatures.

10. European Union Agency for the Operational Management of Large-Scale IT Systems in the Area
of Freedom, Security and Justice (eu-LISA), Distributed Ledger Technologies and Blockchain:
Perspectives for eu-LISA and the Large-scale IT Systems, Research and Technology Monitoring
Report, 2019, p. 21, https://www.eulisa.europa.eu/Publications/Reports/DLTs%20and%20
blockchain%20report.%20Dec%202019.pdf#search=Perspectives%20for%20eu%2DLISA%20
and%20the%20Large%2Dscale%20IT%20Systems.
11. International Civil Aviation Organization (ICAO), “Doc 9303: Machine Readable Travel Documents”,
Seventh Edition, 2015, https://www.icao.int/publications/Documents/9303_p10_cons_en.pdf.
12. Hyperledger, “Hyperledger Indy”, Projects, https://www.hyperledger.org/projects/hyperledger-indy.

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