Internet
Infrastructure
Review
Sep.2019

Vol.

43

Periodic Observation Report

Messaging Technology
Focused Research (1)Blockchain-based
Identity Management and Distribution
Focused Research (2)IIJ’s eSIM Initiatives

Internet Inf rast ruc ture Review
September 2019 Vol.43

Executive Summary ........................ ................................................ 3
1. Periodic Observation Report .......... ................................................ 4
1.1
1.2
1.3
1.4
1.5
1.6

Introduction ............................................................................... 4

Spoofed Emails and Information Breaches .................................................. 4
Sender Authentication Rates ............................................................... 4
Encryption of Email Delivery Channels . .... ................................................ 7

About JPAAWG .......................................................................... 10
Conclusion ................................ ............................................... 11

2. Focused Research (1) ................................................................. 12
2.1
2.2
2.3
2.4
2.5

Introductions ............................................................................. 12
IDs and Credentials as Identifiers . ........................................................ 12
Overview of ERC-725 . .................... ............................................... 13
Decentralized Identifiers, DIDs ............. ............................................... 16
Other Related Developments .............................................................. 18

3. Focused Research (2) ................................................................. 20
3.1
3.2
3.3
3.4
3.5

2

What is an eSIM? ......................................................................... 20
How eSIM Works .......................... ............................................... 21
Moves by Major Vendors .................. ............................................... 25
IIJ’s Initiatives ............................................................................ 26
eSIM Use Cases and Future Trends ........ ............................................... 27© Internet Initiative Japan Inc.

Sep.2019

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43

Executive Summary

Executive Summary

The 30-year-long Heisei era has come to a close, giving way to the Reiwa era this past May. Heisei began in
1989, well before the Internet went mainstream, with the first commercial Internet services being launched in
1993. Windows 95, which contributed greatly to the spread of the Internet, was released in 1995. Google wasfounded in 1998. NTT Docomo launched i-mode, an Internet connection service for mobile phones, in 1999.
NTT East and NTT West launched the BFlet’s FTTH service in the year 2000. It was in 2001 that NTT Docomo
launched FOMA, the world’s first 3G mobile phone service. Apple released the first iPhone in 2007. And in 2010,
NTT Docomo launched its 4G mobile phone service, Xi. The Heisei era’s 30 year run saw substantial advances
in information communications not only in Japan but across the globe.
This is our first IIR issue of the Reiwa era. While 5G mobile services are set to roll out in some countries, the monopolization of information by large platform operators has become problematic. In Japan last year, the Ministryof Internal Affairs and Communications launched a comprehensive assessment of competition rules in the telecommunications business, with an expansive scope covering not only the network layer but the platform anddevice layers as well. Under discussion is a vision for the country’s networks with a view to 2030. Informationand communication technology will continue to make immense contributions to the advancement of society, andwe at IIJ hope to play our part as well.
The IIR introduces the wide range of technology that IIJ researches and develops, comprising periodic observation reports that provide an outline of various data IIJ obtains through the daily operation of services, as well as
focused research examining specific areas of technology.
Our periodic observation report for this issue, found in Chapter 1, looks at messaging technologies with a focus
on email. We examine deployment rates for SPF, DKIM, and DMARC sender authentication based on communications received via IIJ’s email servers. Although SPF is quite well known, awareness of DMARC is yet to move
forward. In light of survey data indicating that 80% of federal government domains in the United States have
DMARC records, we will need to do something to raise awareness of DMARC in Japan. The report looks at deployment rates for sender authentication, discusses the encryption of email delivery routes, and describes theactivities of M3AAWG and JPAAWG, in which the author himself is involved.
Our first focused research report for this issue in Chapter 2 discusses identity management and distribution basedon blockchain technology. The report looks at ERCs (Ethereum Requests for Comment) that use the Ethereum
blockchain for credentials and touches on use cases in which credentials are used as public certifications. It also
discusses the focus on blockchain-based credential management technologies, with several vendors having put
forward concepts like DIDs (Decentralized Identifiers) and SSI (Self-Sovereign Identity) in the past few months.
Our second focused research report in Chapter 3 is about eSIMs. IIJ became a so-called full MVNO last year,with its own HLR/HSS systems. One feature that becoming a full MVNO enables IIJ to provide is eSIMs. The
report explains why eSIMs are necessary and how they work, and then discusses IIJ’s and other companies’
initiatives in this area. The process of setting up communication services contracts is set for major changes in aworld where physical SIM cards are not required and the profiles used to manage communications contracts are
passed around as electronic data.
Through activities such as these, IIJ strives to improve and develop its services on a daily basis while maintaining
the stability of the Internet. We will continue to provide a variety of services and solutions that our customers
can take full advantage of as infrastructure for their corporate activities.

Junichi Shimagami
Mr. Shimagami is a Senior Executive Officer and the CTO of IIJ. His interest in the Internet led to him joining IIJ in
September 1996. After engaging in the design and construction of the A-Bone Asia region network spearheaded by IIJ,
as well as IIJ’s backbone network, he was put in charge of IIJ network services. Since 2015, he has been responsible
for network, cloud, and security technology across the board as CTO. In April 2017, he became chairman of theTelecom Services Association of Japan MVNO Council.

© Internet Initiative Japan Inc.

3

1. Periodic Observation Report

Messaging Technology

1.1 Introduction

and breaches of confidential and personal information re-

The IIR has continued to report on quantitative trends insulting from the capturing of IDs and passwords, malware

spam and its content, and as described in IIR Vol. 39, from

infections, and the like.

here out we will be focusing on explaining and chronicling
the spread of messaging technologies, including technolo-

A number of incidents have spurred these sorts of occur-

gies designed to combat spam.

rences on. A spate of information breaches from a variety of
Web services have occurred, with email addresses included

In this issue, we go over the results of a survey on the spreadin the information exposed in almost all cases, making itof sender authentication technologies, particularly DMARC,

possible for spammers to direct spam with precision. Newsand explain MTA-STS, a mechanism described in an RFC lastalso came of a massive breach of personal information fromyear that relates to TLS encryption connection policies fora major hotel chain last year, and reams of spam have sub-email delivery channels, as well as SMTP TLS Reporting, asequently made their way into the inboxes of the exposedmechanism for reporting of TLS connection information. In

addresses. Some such spam messages even contain a login

relation to messaging, we report on the JPAAWG 1st Generalpassword. Services available via the Web can be conve-

Meeting, held last year and co-hosted alongside the Anti-nient, but the service provider’s security cannot always be

spam Conference, as well as on JPAAWG itself.

trusted. Users need to properly understand the strength ofpasswords and other information they set on Web services,

1.2 Spoofed Emails and Information Breaches

as well as the types of services for which the same pass-

Emails spoofed to appear as though they were sent bywords are used.

someone else cause so many kinds of problems that they
are given names like phishing emails and BECs (Business1.3 Sender Authentication Rates

Email Compromises). The damage caused by such emails is

We have noted previously that sender authentication is anboth serious and wide ranging, including financial damages

effective countermeasure against email spoofing. Settings

none

14.3%

temperror

0.1%

permerror

1.4%

neutral0.7%

softfail

7.0%

hardfail

6.5%

pass 70.1%

Figure 1: Breakdown of SPF Authentication Results

4© Internet Initiative Japan Inc.

Sep.2019

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1. Periodic Observation Reportneed to be configured on both the sending and receiving

authentication was not possible, so turning this around, it

ends. Email recipients can use authentication to detectmeans that 85.7% of emails received were from senders

spoofed emails, while senders can configure their sys-that have implemented SPF. The year-earlier (April 2018)tems to ensure that their emails can be distinguished fromfigure for “none” was 16.0%, around the same level,spoofed ones.

which indicates that sender authentication has spread to apoint that the vast majority of received emails can be SPF

If we are to promote the spread of sender authentication,authenticated.

we first need to understand how far it currently permeatesthe space. Here, we report on two sets of survey results,

Figure 2 shows a breakdown of DKIM authentication results.

one looking at volume-based deployment rates among send-

As a proportion of the total, the figure for “none” is 62.2%,

ers from a recipient perspective, and the other looking at

which indicates that less than 40% of emails received were

the proportion of registered domain names on which senderfrom senders that have implemented DKIM. The year-earlier

authentication is implemented.

figure for “none” was 62.4%, so DKIM deployment rates
have not changed that much.

1.3.1 Volume-based Deployment rates
Here, we go over the spread of sender authentication among

Figure 3 breaks down DMARC authentication results. And

senders from an email recipient perspective based on emailby the same measure, the figure for “none” here is 76.9%,

authentication data for emails received via IIJ’s email ser-indicating that around 20% of emails received were from do-vices in April 2019.

mains where the sender has implemented DMARC. DMARC
authentication uses the results of SPF and DKIM, so it is

Figure 1 shows a breakdown of SPF authentication re-predictable that authentication rates here will be lower thansults. Of all emails received, SPF authentication returnedfor SPF and DKIM. That said, and although the resending of“none” for 14.3%. A value of “none” indicates that SPF

emails is an issue, emails can be DMARC authenticated via

pass 35.6%

pass 15.2%
fail 7.7%
permerror 0.1%
temperror 0.1%

none

62.2%

none

76.9%

fail 1.1%
neutral 1.1%

Figure 2: Breakdown of DKIM Authentication Results

Figure 3: Breakdown of DMARC Authentication Results© Internet Initiative Japan Inc.

5

SPF alone, so the figure is really quite low considering thatfor the purpose of gauging the spread of sender authentica-

the SPF deployment rate is above 80%.

tion technology. I am taking part in the studies as a visiting
researcher for the Japan Data Communications Association.

Figure 4 shows the results for DMARC since January
2016. Initially, the figure for “none” was 87.5%, so on a

Figure 5 shows the results for March 2018 onward. For

volume basis, the deployment rate has risen by around 10

domain names configured with an MX record, which indi-

percentage points over almost three years. The proportion

cates the domain name is used for email, the graph shows

has roughly doubled. Although changes in the proportion

what proportion had a DMARC record configured, brokenof “fail” results have fluctuated over time, the data show

down by type of jp domain. According to the latest datathat the proportion of all emails that can be authenticated,from May, this was 0.95% of jp domains overall. By type,including those for which authentication fails, is graduallyad.jp tops the list, but still only with a figure of 3.4%. Next

rising.

down the list with 2.1% is go.jp, which has a step-function
look to it on the graph because the number of such domains

1.3.2 Deployment Rates Based on Registered Domain Names

registered is small.

Next, for registered jp domain names, we look at whether
SPF or DMARC is implemented. As noted previously in Vol.

Materials*1 disclosed by NISC (the Cabinet Office’s cyber-

39, we have a joint research agreement with the Japansecurity center) indicate that the use of SPF, DKIM, andRegistry Services (JPRS)—which manages jp domain

DMARC on the sender and receiver sides is listed as a mea-

names—and the Japan Data Communications Association

sure for preventing email spoofing within the information

(%)
100

75

50
■none
■permerror■temperror
■fail
■pass

25

0

Fe
b.
M
ar
.
Ap
r.

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ar
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ay
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’19

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ar
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Ap
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ay
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’1
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ar
.
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Au
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Se
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No
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’18

(Date)

Figure 4: Breakdown of DMARC Authentication Results Over Time

*1

“Guidelines on the Formulation of Information Security Measures for Government Agencies and Related Bodies (2018 Edition)” (in Japanese at https://www.nisc.
go.jp/active/general/pdf/guide30.pdf).

6© Internet Initiative Japan Inc.

Sep.2019

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43

1. Periodic Observation Reportsecurity strategy for government bodies. This means we canindustries surveyed. As I reported last time, this increase

expect the proportion of go.jp domains with a DMARC re-likely traces to a legally binding order*3 issued by the United

cord configured to increase ahead. Note also that registered

States Department of Homeland Security. And according togo.jp domains top the list for the proportion with an SPF

DMARC.org, a group that advocates for the use of DMARC

record configured (Figure 6).

technology, the number of domains in the DNS with DMARC
records increased by over 2.5-fold in 2018*4.

Similarly, the proportion of all jp domain names with an
SPF record configured was 59.7%. This is a 2.8-percent-

1.4 Encryption of Email Delivery Channels

age-point increase vs. the previously reported figure of

Email is used not only to exchange simple messages but

56.9% (Vol. 39). The fact that this SPF adoption rate isalso as a means of transferring various types of data via

still rising seems to indicate that awareness of SPF is quite

attachment capabilities (MIME). Meanwhile, it does seemhigh. Unfortunately, the rate of increase for DMARC is quitethat users do not give much consideration to what route

low compared with that for SPF, so we will need to boost

an email that contains data will take when being delivered

awareness of DMARC somehow.

nor to what level of data leakage risk exists. The SMTP
email delivery protocol can use TLS (STARTTLS) as an ex-

1.3.3 Deployment rates Overseas

tension. Here, we discuss issues with this conventional

According to a survey

by the US-based Valimail, 80%

STARTTLS protocol and standards established to addressof federal government domains in the United States havethose issues, namely MTA-STS and SMTP TLS Reporting.

*2

DMARC records. This was the highest rate among the(%)
4■average
■gen
■geo
■lg
■ed
■gr
■ne
■or
■go
■co
■ac
■ad

3

2

1

3.
9.
20
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3.
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6
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8
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7.
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7
9.
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9.
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28
10
.
10 5
.1
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1. 2.28
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8
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4.
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4.
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5.
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10

0

(Date)

Figure 5: Proportion of jp Domains with a DMARC Record
（％）
100

75

50

25

0
ad

ac

co

go

or

ne

gr

ed

lg

geo

gen average

Figure 6: Proportion of Domains with an SPF Record Declaration*2

Email Fraud Landscape, Q4 2018 (https://www.valimail.com/resources/email-fraud-landscape-q4-2018/).

*3

DHS, “Binding Operational Directive 18-01” (https://cyber.dhs.gov/bod/18-01/blank).

*4

DMARC Policies Up 250% In 2018 (https://dmarc.org/2019/02/dmarc-policies-up-250-in-2018/).

© Internet Initiative Japan Inc.

7

1.4.1 Issues with STARTTLS

1.4.2 MTA-STS and TLSRPTThe SMTP extension STARTTLS (TLS) is used to encrypt

MTA-STS*5 is a mechanism in which recipient domains use

the channel when emails are delivered. The procedure is

a combination of DNS and HTTPS to publish their receiving

as follows: if the Recipient mail server supports STARTTLS

policies. This mechanism allows you to determine whether(determined by the response when connecting), the sender

TLS authentication is supported before sending an email andsends a STARTTLS command to start a TLS session. So thewhat action the sender should take if a TLS connection can-channel cannot be encrypted under the following conditions.

not be established.

• Recipient mail server does not have STARTTLS (doesRecipient domains should make the following settings.

not return a response to STARTTLS)• The STARTTLS command is sent in order to start a
TLS session but the available TLS version and cipher(1) Configure an MTA-STS record(2) Set a “well-known” path so that the MTA-STS policy
can be fetchedsuites do not match
Cipher suites are combinations of encryption algorithms,

The MTA-STS record is usually a TXT record that is named

key length, and so on. Encrypted communications are notby adding “_mts-sts” to the destination domain and thatpossible unless both sending and receiving ends are able tostarts with the string “v=STSv1”. So if the mail destina-

use the same cipher suite. If the STARTTLS command can-tion domain is “example.com”, the record is configured as

not be executed, many sending email servers will switch

follows.

to conventional unencrypted plaintext email transmission.
This setup exposes email to a sort of man-in-the-middle_mta-sts.example.com. IN TXT "v=STSv1; id=20160831085700Z;"

attack because by intercepting the SMTP session and deleting the intended recipient server’s STARTTLS response,

The id parameter is a string that can be used to determine

an attacker can force plaintext transmission and snoop thewhen the policy has been updated. By first referring to thiscontents of email. This sort of technique is also called a

MTA-STS record, the sender can check whether the recipi-

downgrade attack.

ent domain supports MTA-STS.

*5

8

SMTP MTA Strict Transport Security, RFC 8461

© Internet Initiative Japan Inc.

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1. Periodic Observation Report

To fetch the MTA-STS policy, the sender refers to the

The TLSRPT*6 specification is used to report to the sender“well-known” path on the policy domain prepended with

if the policy verification succeeds or fails under MTA-STS or“mta-sts”. The “well-known” path is described in RFC

other mechanisms such as DANE*7. Senders use the DNS

5785. In the case of MTA-STS, it is fetched via an HTTPS

to publish a TLSRPT policy for receiving reports. Email re-

GET request for the following path.

cipients that support TLSRPT first determine whether thisTLSRPT policy has been specified by the sender domain,and if fetchable, a report is sent to the report recipient, if

https://mta-sts.example.com/.well-known/mta-sts.txt

specified, in that policy. The TLSRPT policy settings can be
The MTA-STS policy contains line feed-separated (CRLF-

retrieved by prepending “_smtp._tls” to the target domain.

separated)

The parameters are quite similar to those for DMARC*8 but

key/value

pairs.

The

currently

allowableparameters are shown in Table 1.

differ in that “v=TLSRPTv1” specifies version 1 of TLSRPT
and the “rua=” field, which specifies where the report is“max_age” specifies how long the policy should be cached.

to be submitted, can specify the mailto schema (“rua=-“mx” specifies patterns matching hostnames given in themailto:”) as well as HTTPS (“rua=HTTPS:”). An example of

MX record. Multiple hosts and patterns can be set. Table 2

a TLSRPT policy record appears below.

shows the allowable values for operation mode (“mode”).
The sending MTA determines whether to continue sending
emails based on the value of this “mode” field.
An example of an MTA-STS policy appears below.

̲smtp.̲tls.example.com. IN TXT "v=TLSRPTv1;rua=mailto:reports@example.com"

When emailing reports to destinations specified using “rua=mailto:”, the report must contain a DKIM signature by
the sender domain. The DKIM record of the sender providing

version: STSv1
mode: enforce
mx: mail.example.com
mx: *.example.net
mx: backupmx.example.com
max_age: 604800

the DKIM signature SHOULD contain the “s=tlsrpt” service
type declaration.

Table 1: MTA-STS Policy Parameters

Table 2: MTA-STS Policy Modes

Parameter

Meaning

Operation mode

Meaning

versionThe version (currently only “STSv1”)

enforce

Messages are not delivered to hosts that fail policy validation or TLS

mode

Expected behavior of sender if policy validation fails

testing

max_age

Max lifetime of the policy (in seconds)

Report sent if sending MTA implements TLSRPT*6;
messages continue to be deliveredmx

Allowed MX record patterns

none

Indicates that no explicit MTA-STS policy is applied*6

SMTP TLS Reporting, RFC8460*7

The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA, RFC 6698

*8

Domain-based Message Authentication, Reporting, and Conformance (DMARC), RFC 7489

© Internet Initiative Japan Inc.

9

Based on this, Figure 16 shows plots of total traffic of theselector._domainkey.example.com IN TXT"v=DKIM1; k=rsa; s=tlsrpt; p=Mlf4qwSZfase4fa=="

past 10 years. The data series are stacked. The outbounddata are observations made at entry points, and the inbounddata are observations made at exit points. Some traffic is

Reports sent via email are sent as attachments (MIME)

eliminated within the backbone, such as that involved in at-in the same manner as DMARC reports. An example of atacks, but generally all traffic that comes into the backbone

TLSRPT policy record for sending reports over HTTPS also

also exits at some point, so the totals are almost the same.

appears below.

1.5 About JPAAWG_smtp._tls.example.com. IN TXT "v=TLSRPTv1; rua=https://reporting.example.com/v1/tlsrpt"

The IIR has mentioned the international antispam organization M3AAWG*9 several times in the past. Recently, it has
also become a forum for a range of discussion on highly

Report data should be compressed for both email and HTTPS

relevant security issues beyond that of email. It has alsotransport. Whether applying compression or not, the media

been supporting the establishment of regional organizations

type should be consistent with the format (“application/tl-

beyond North America and Europe, where many M3AAWG

srpt+gzip” or “application/tlsrpt+json”). Reports are sent

members reside. A recently formed group is LAC-AAWG forin JSON format, unlike DMARC reports. We do not go overLatin America and the Carribean. The organization is also

the parameters given in the report data here, but details canworking toward and supporting AFR-AAWG for Africa. Thisbe found in RFC 8460.

leaves only the issue of Asia and what to do there.

*910

Messaging, Malware and Mobile Anti-Abuse Working Group© Internet Initiative Japan Inc.

Sep.2019

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1. Periodic Observation Report

IIJ has long been an active member in M3AAWG since it

and key members of M3AAWG. With the event’s success,was established, but the number of participants from Japan

we made preparations for ongoing JPAAWG activities, cul-

has not really risen as much the number from the US andminating in JPAAWG being formally established on May 30,

Europe. To increase the number of participants, we have2019. We hope JPAAWG’s future activities will be of inter-been publicizing the M3AAWG’s activities in Japan andest to you.

sounding out the prospects of holding an M AAWG General
3

Meeting in Japan or Asia from time to time. Against that

1.6 Conclusion

backdrop, M AAWG has been making efforts to support

In this issue, we described MTA-STS, a technical specifi-

M3AAWG-linked activities in other regions. And out of thatcation for reliably ensuring encryption of email deliveries,

process emerged efforts among M3AAWG and participants

and TLSRPT as a means of ascertaining what operations

from Japan to set up JPAAWG.

have taken place. So far, the IIR has looked at sender au-

3

thentication technologies including DMARC, ARC, andAs an organization, JPAAWG (Japan Anti-Abuse Working

DANE, but email-related technical specifications continue toGroup) is entirely independent of, but receives considerable

evolve along with new specifications such as BIMI (Brand

support from, M3AAWG. The JPAAWG 1st General Meeting

Indicators for Message Identification) and JMAP (JSON Meta

on November 8, 2018, was held in conjunction with theApplication Protocol). Going forward, the IIR will continue toInternet Association Japan’s Anti-Spam Conference, an

discuss new technical specifications and the background toevent that has been running for over a decade, and attracted

their development.

many speakers and participants. Speakers included the chair

Shuji Sakuraba
Senior Manager, Application Service Department, Network Division, IIJ. Mr. Sakuraba is engaged in the research and development of communication
systems. He is also involved in various activities in collaboration with related external organizations aimed at bringing about safe and secure messaging
environments. He has been a member of M3AAWG since its establishment. He is the chair of the Japan Anti-Abuse Working Group (JPAAWG).
He is acting chairperson of the Anti-Spam mail Promotion Council (ASPC) and a member of its administrative group, as well as chief examiner for
the Technology Workgroup. He is chairman of Internet Association Japan’s Anti-Spam Measures Committee. He is a member of the Email Security
Conference program. He is a visiting researcher for the Japan Data Communications Association. And he is a visiting researcher at JIPDEC.

© Internet Initiative Japan Inc.

11

2. Focused Research (1)Blockchain-based
Identity Management and Distribution
2.1 Introductions

Real-world entities are linked with digital-world entities, andEveryday, it seems, media reports about various services

a unique identifier (which we will denote “ID”) is assigned

based on blockchain technology appear. Among these are

to identify the digital-world entity. The notion of an ID as

many unfortunate ideas that merely use blockchains as a dis-an identifier must be kept conceptually separate from thetributed database, so much so that a number of flowcharts

various identity information that is bound to that ID. Further,for determining whether you really do need to use block-because realms (the scope within which the ID is valid andchains have been published*1. There are several methods

can be used to identify something) are separately defined forof classifying blockchains; broadly, they can be classified

each ID space, a single, unique entity in the real world caninto private-use blockchains and public blockchains thathave multiple IDs even within the same realm.

underpin the security of cryptographic assets. With publicblockchains, it is necessary to incentivize ongoing mining to

Now the reason IDs are assigned in the digital space is that

extend the chain; for cryptoassets such as Bitcoin, it is nec-

there is a need for third parties on the network to identify

essary to extend the chain based on predefined rules. With

the entities to which IDs are assigned. The act of authenti-

cryptoassets, the main reason for using blockchain is tocation accompanies all sorts of activities in the digital world.

transfer assets from one address to another, but efforts are

Authentication allows access to various resources and ser-also being made to use this blockchain-based value-transfer

vices, for instance.

platform for other applications. These are being called second layer or Layer 2 applications.

This act of authentication can be accomplished by using
pairs of tokens (secret information) and credentials (public

Here, we look at developments in ERCs (Ethereum Requests

information). According to the definition in NIST SP 800-

for Comment)*2 used for credentials (identity information) from63, a token contains a secret known to the user to which*3

among the second-layer services for the Ethereum blockchain .

the ID in question has been assigned, and credentials bind

We will also touch on use cases in which such credentials arevarious attributes to the ID. Cryptographic techniques are

stored in the blockchain, enabling public certifications, suchused to ensure the integrity of credentials. Credentials use

as student or employee IDs, to be verified digitally. Finally,

cryptographic techniques to ensure content integrity. When

we also go over why several vendors and consortiums havethe entity that holds the ID seeks verification of his or her

put forward concepts such as Decentralized Identifiers (DIDs)

attributes by a third party in the digital world, the token (se-and Self-Sovereign Identity (SSI), where the user is in control

cret information) can be used to verify that the holder of theof managing their own identity, and take a look at the focus

ID is the entity to which it was assigned.

on technology for managing credentials based on blockchains.
When a credential is presented together with an authentica-

2.2 IDs and Credentials as Identifiers

tion operation, a receiving third party can verify what sort ofIn focused research pieces back in 2015, we reported on

entity the ID is using the attributes given in the credential. In

trends in ID management technology at the time*4*5*6. Here,addition to authentication in this manner, credentials are also

we consider IDs in the narrow sense of identifiers.

used for authorization in some cases. An X.509 certificate is*1

NISTIR 8202, “Blockchain Technology Overview” (https://doi.org/10.6028/NIST.IR.8202), Figure 6: DHS Science & Technology Directorate Flowchart.

*2

Ethereum Improvement Proposals (http://eips.ethereum.org/).

*3

Ethereum Project, Developer Resources (https://www.ethereum.org/developers/). In this volume, we do not cover technology related to smart contracts, a key
feature of Ethereum.

*4*5Internet Infrastructure Review Vol. 26, “1.4.3 ID Management Technology” (https://www.iij.ad.jp/en/dev/iir/pdf/iir_vol26_EN.pdf).
Internet Infrastructure Review Vol. 27, “1.4.2 ID Management Technology: From a Convenience and Security Perspective” (https://www.iij.ad.jp/en/dev/iir/pdf/
iir_vol27_EN.pdf).

*6

Internet Infrastructure Review Vol. 28, “1.4.3 ID Management Technology: Online Authentication Methods Not Using Passwords” (https://www.iij.ad.jp/en/dev/iir/
pdf/iir_vol28_EN.pdf).

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2. Focused Research (1)an example of a credential because it binds a public key with

Smart contracts, a method for automatically executing

one or more IDs. And in fact, SSL/TLS client authentication

contracts and performing services, are a new concept put

is one case of this. Deploying a personal X.509 certificate

forward by Nick Szabo in 1997 and thus predate Bitcoin. A

on the browser side allows a user to log in to a server, andcommonly cited example of a smart contract is the vending

this is used in applications like corporate online banking.

machine. When certain conditions are met by two processes,

A specification for X.509 Attribute Certificatesprovidesnamely that the user inserts payment for the desired bever-a method that is closer to credential-like usage. Attributeage into the machine and the user subsequently presses thecertificates differ from ordinary X.509 certificates in that

button corresponding to that beverage, a sale is automaticallythey do not contain a public key. A serial number used toinitiated. As well as being used for cryptoassets, Ethereum

identify the certificate is placed in an area for storing identi-

is also being viewed as a distributed application platform

fiers called the Holder so as to specify the X.509 certificate,enabling the creation and execution of smart contracts*11.

and attributes bound to the certificate holder (subject) are

ERC-725 defines a Solidity interface for the behavior of athen stored. Here the realm can be understood to be theproxy account. Solidity is a language used to write distributed

certificates issued by the certification authority, the ID toapplications. ERC-725 refers to ERC-735*12 and ERC-780*13

be the serial number, and the credentials to be the attributeand provides a framework for distributing credentials on thecertificate. Credentials can be written to X.509 Attribute

Ethereum blockchain based on these specifications. In theCertificates, but they are not actually implemented in appli-

ERC-725 document, credentials are called claims. ERC-735

cations that general users are likely to encounter, such as

describes the format of claims, and ERC-780 describes anbrowsers, so there are hardly any cases of them being used

Ethereum Claims Registry (ECR). Under the framework spec-

at present.

ified in the Ethereum blockchain realm, an ID (identifier) is
​​ an

*7

Ethereum address (note that it is not a contract address), and2.3 Overview of ERC-725

the identity information of the identity holder bound to the

ERC-725*8 was proposed in October 2017 by software

address is certified by credentials, called claims. The claim

engineer Fabian Vogelsteller*9, known for developing theissuer can issue a claim to any entity on the Ethereum block-ERC-20 token standard and web3.js. Like the IETF’s RFCs,

chain using a private key in the claim issuer’s possession. The

ERCs (Ethereum Requests for Comment) are documented

identity holder passes the claim to be verified to the claim

proposals for improvements that anyone can author; thechecker via some method, and the claim checker can verify

format and writing guidelines are given in ERC-1. A major

the claim’s veracity by verifying the digital signature. It isfeature worth noting is that authors are asked to keep theirenvisioned that this series of verification tasks can be per-proposals compact. A similar class of documents exists informed both online and offline*14.

the Bitcoin community, known as BIPs (Bitcoin Improvement
Proposals)*10. The method for reducing transaction data

Claims as specified in ERC-735 have the following simple

known as SegWit, for instance, is defined in BIP-141.

data structure.

*7

RFC 5755, “An Internet Attribute Certificate Profile for Authorization” (https://datatracker.ietf.org/doc/rfc5755/).

*8

ERC-725 version 2: Proxy Account (https://github.com/ethereum/EIPs/issues/725) (http://eips.ethereum.org/EIPS/eip-725).

*9

Fabian Vogelsteller (http://frozeman.de/blog/).

*10

BIP (Bitcoin Improvement Proposals) (https://github.com/bitcoin/bips).

*11

Ethereum Project white paper (https://github.com/ethereum/wiki/wiki/White-Paper).

*12

ERC-735: Claim Holder (https://github.com/ethereum/EIPs/issues/735).

*13

ERC-780: Ethereum Claims Registry (https://github.com/ethereum/EIPs/issues/780).

*14

Fabian Vogelsteller, ERC Identity (https://www.slideshare.net/FabianVogelsteller/erc-725-identity).

© Internet Initiative Japan Inc.

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So under the ERC-725 framework, anyone can issue a claim.

struct Claim {uint256 topic;
uint256 scheme;
address issuer;
bytes signature;bytes data;
string uri;}

In other words, anyone can be a claim issuer, so you canissue a claim to anyone as long as you know their Ethereum
address. A key issue, therefore, is how to establish trust fora claim issuer and how to value the claims issued by thatissuer. There also appears to be functionality to allow, for

ERC-735 claims should be implemented to enable the iden-

example, claims to be revoked and the Ethereum address totity holder to present them to the claim checker, and a key

be swapped out, but the specification is still incomplete incharacteristic is that the data are portable. ERC-735 provides

this regard. It also seems that discussion over what reputa-

a zone for writing URIs to an area that is not ToBeSigned,tion system to use for issuers has only just begun.

and it is here that data pointing to the identity informationis shared via a distributed file system such as IPFS*15. The

So we are straddled with a problem of reputation, and we

ERC-725 Alliance*16 has an open-source project related towill probably need to work through a few stages before we

ERC-725. Also, a number of samples are available on

are ultimately able to distribute claims the way we would

sites*18 built using this demo implementation, showing how

like. My view is that the notion of claims will gradually gain

the veracity of claims can be verified in the browser. It is

traction via the following three steps. In the first stage, ac-worth noting that the specification allows you to sign yourquaintances in closed networks, such as SNS, will casuallyown identity information and thus make your own claims

issue claims to one another. This phase will determine scal-

about yourself.

ability. The next stage will see the formation of a framework*17

Table 1: Elements of the ERC-735 Claim Structure

14

Topic

Currently marked as ToBeDefined. A 256-bit space expected
to contain information on the topic (or type) of claim.

SchemeToBeDefined. A 256-bit space to hold the processing
method or signature algorithm to use, which would refer toseparately defined schemes.

IssuerA contract address or the Ethereum address of the key
used to sign the signature.

Signature

Note that the signed data needs to be of the following
structure: {identity holder’s Ethereum address, topic, data}

Data

The hash of the identity information (claim data). The identity
information itself is not written here, so sensitive information
is not being written to the blockchain.

Uri

A URI pointing to the identity information. HTTP link, IPFS
URI, or such like.

*15

IPFS (InterPlanetary File System) (https://docs.ipfs.io/introduction/).

*16

ERC-725 Alliance (https://erc725alliance.org/).

*17

ERC-725 Alliance, “Repository for code and discussion around ERC725 and related standards” (https://github.com/ERC725Alliance/erc725/tree/master/contracts/contracts).

*18

ERC 725: Demo implementation by Origin Protocol (https://erc725.originprotocol.com/); Origin Protocol, Inc. (https://www.originprotocol.com/).

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2. Focused Research (1)for ranking issuers using existing user evaluation/reportingon the scene, so when selecting a platform, the businesssystems to assess whether they have issued incorrect

continuity prospects need to be taken into account.

claims or not. And finally, this will develop into a completely
distributed, automated reputation system (Figure 1).

As discussed so far here, claims embody a simple mechanism, but if the Issuer is trustworthy and the second-layer

The Blockcerts

project is another example of the use of

specification works properly, it is understood they can be

portable claims in a vein similar to ERC-725; there are open-

used on a semipermanent basis so long as the reliability ofsource code

*19

available as well.

the Ethereum blockchain remains intact. So the digital issu-

Blockcerts is based on prototypes developed at the MITance of diplomas is one application apt for making good use

Media Lab and Learning Machine. Work is ongoing to extendof blockchain technology, and indeed, some such services

Blockcerts to implement multiple blockchain types, including

have appeared in Japan. Once trusted organizations do not

Bitcoin and Ethereum. A smartphone app called Blockcerts

persist indefinitely, as attested by the closure of private

Wallet has also been implemented and released, and MIT

schools in regional areas and the discontinuation of certi-

is now using the Blockcerts technology to write students’fying exams by local governments. There are even cases

diplomas to the blockchain*22. And a Spanish university hasof physical certificates issued by such organizations no lon-

also announced that when issuing degree certificates, it will

ger being validatable. Hopefully, we are bound for an era

use the SmartDegrees platform so that they can be man-in which claims distributed via an open framework, as dis-

aged on the Ethereum blockchain*23. The situation is a tadcussed here, provide an alternative to physical certificates.

*20

and verification demos*21

chaotic at present with multiple such second-layer platforms

A framework whereby Reputators evaluate
the Claim Issuer is needed

Trust
Claim Issuer

Can the Claim’s veracity be determined?
Certified

Claim

Claim

Claim

Claim

Claim

Claim

Claim

Identity Holder

Claim Checker

Figure 1: Framework for Issuing and Valuing Claims*19

Blockcerts (https://www.blockcerts.org/).

*20

Repositories of the Blockcerts project (https://github.com/blockchain-certificates).

*21

Example Blockcerts (https://www.learningmachine.com/new-product/examples/).

*22

MIT News, Digital Diploma debuts at MIT (http://news.mit.edu/2017/mit-debuts-secure-digital-diploma-using-bitcoin-blockchain-technology-1017).

*23

Universidad Carlos III de Madrid is issuing degree certificates with blockchain (https://www.uc3m.es/ss/Satellite/UC3MInstitucional/en/Detalle/Comunicacion_C/1371252827656/1371215537949/Universidad_Carlos_III_de_Madrid_is_issuing_degree_certificates_with_blockchain).

© Internet Initiative Japan Inc.

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2.4 Decentralized Identifiers, DIDs

The notion of Decentralized Identifiers (DIDs) emerges from

As identifiers, IDs are assigned within a specific realm. When

this backdrop. A feature of DIDs is that they are not valid

it comes to authenticating across realm boundaries, the no-

IDs only in one specific realm and there is no centralized

tion of the ID Federation comes into play and often appears

presence that manages the IDs. This is seen as highly com-in a single sign-on context. Credentials such as the X.509

patible with the notion of Self-Sovereign Identity (SSI)*24

Attribute Certificates and ERC-735 claims we have discussed

proposed by the nonprofit Sovrin Foundation*25. SSI is simi-

only circulate within the realm in which they were issued.

lar to the idea that individuals have the right to control their

In reality, identity providers, whose role is also to issue IDs,

own information. The term is used in recognition of the need

do not exist in isolation. To enable the login functionality offor individuals to own and manage their own identities with-service providers, such as SNSs, to be used from external

out going through a central managing authority. Credentials

services, that functionality is split off into the identity pro-such as ERC-735 claims, as discussed above, can be passed

vider role. As such, in cases where ID linking functionality isaround without the identity holder intending it. Not so withused to log in to separate services, there is a risk that the ID

SSI; instead, the idea is that the identity holder has sover-will suddenly stop working because it is operated by a partic-

eignty over the distribution of his or her credentials.

ular company or organization. Thus, the deactivation of one
ID could result in an inability to use several other services.

The nonprofit ID2020 Alliance*26 is an organization that

The deactivation—or in the worst case, deletion—of an ID

seeks to achieve privacy protection and portable, user-cen-because an SNS operator decided that inappropriate content

tric identity management. There is also a project*27 that

had been posted can have negative impacts, and indeed there

looks to use claims written to a blockchain as an alterna-

have been various real-world cases of this.

tive to passports, analogous to the way people seek to use*24

The Sovrin Alliance, “Sovrin: A Protocol and Token for Self-Sovereign Identity and Decentralized Trust” (white paper, version 1.0, January 2018) (https://sovrin.
org/wp-content/uploads/Sovrin-Protocol-and-Token-White-Paper.pdf).

16

*25

The Sovrin Alliance (https://sovrin.org/library/rise-of-self-sovereign-identity/).

*26

ID2020 Alliance, The Alliance Manifesto (https://id2020.org/manifesto).

*27

Taqanu (https://www.taqanu.com/impact).

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2. Focused Research (1)cryptoassets rather than legal currency in cases where the

distributed ledger technology or other form of decentralized

reliability of nationally issued currencies has diminished.

network*32. ERC-735 claims use Ethereum addresses as the

The idea can be interpreted as follows: data correspond-

ID space, but a method has also been proposed for wrappinging to claims that everyone recognizes and that are issued

Ethereum addresses in the W3C DID format instead of using

by credible institutions can provide a passport-like means

them as raw DIDs*33. So W3C DID is being promoted as aof personal identification. The Sustainable Development

global ID capable of representing a range of IDs. The exis-

Goals (SDGs)*28 compiled by the United Nations in 2015

tence of DIDs alone only solves the issue of nonconflicting

state Target 16.9 as: “By 2030, provide legal identity for

numbering, but in conjunction with the claim use cases*34

all, including birth registration”. And the ID2020 Technicaland the verifiable credentials (originally called claims, theRequirements*29 have been formulated in an attempt towording was later changed to credentials) data format*35,

assist the world’s “identity refugees”, thought to number

they are poised to solve the various other issues faced.

over a billion. The document covers seven categories—
applicability, identification, authentication, privacy, trust,Group work at the Web of Trust VIII event in March 2019

interoperability, and recovery—and is highly useful as a de-(RWOT8)*36 and the 28th Internet Identity Workshop*37

sign guideline of this type.

in April 2019 dealt with many topics centering on DIDs
and SSI. The 2019 annual meeting of the IGF (Internet

The intention behind DIDs, meanwhile, can be gleaned from

Governance Forum)*38 will also cover DID-related technol-

documents developed by the W3C*30*31. The W3C defines

ogy and encompass discussion of governance. So looking

a DID as a globally unique identifier that does not require aahead, many people are lining up to drive the discussion

centralized registration authority because it is registered withforward.

*28

Transforming our world: the 2030 Agenda for Sustainable Development (https://sustainabledevelopment.un.org/post2015/transformingourworld) (https://www.
un.org/ga/search/view_doc.asp?symbol=A/RES/70/1&Lang=E).

*29

ID2020 Technical Requirements: V1.0 (https://docs.google.com/document/d/1L0RhDq98xj4ieh5CuN-P3XerK6umKRTPWMS8Ckz6_J8/edit).

*30

W3C Credentials Community Group (https://www.w3.org/community/credentials/).

*31

W3C Verifiable Claims Working Group (https://www.w3.org/2017/vc/WG/) (https://github.com/w3c/verifiable-claims).

*32

Decentralized Identifiers (DIDs) (https://w3c-ccg.github.io/did-spec/#decentralized-identifiers-dids); latest version as of this writing: v0.13, dated Jun. 3, 2019*33

eth DID Resolver (https://github.com/uport-project/eth-did-resolver).

*34

Verifiable Claims Use Cases (https://www.w3.org/TR/verifiable-claims-use-cases/).

*35

Verifiable Credentials Data Model 1.0 (https://www.w3.org/TR/verifiable-claims-data-model/); latest version: Mar. 2019; a W3C Candidate Recommendation as ofthis writing.

*36

Rebooting the Web of Trust VIII: Barcelona (March 2019) (https://github.com/WebOfTrustInfo/rwot8-barcelona) (https://www.weboftrust. info/pastevents.html).

*37

IIW (The Internet Identity Workshop) Workshop Proceedings (https://internetidentityworkshop.com/past-workshops/).

*38

IGF 2019 Workshop Selection Results (https://www.intgovforum.org/multilingual/content/igf-2019-workshop-selection-results).

© Internet Initiative Japan Inc.

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2.5 Other Related Developments

It is theoretically possible for people to be scored unfairly

In May 2019, Microsoft unveiled a platform to handle

based on obscure logic because they live in a particular re-

DIDs based on the Bitcoin blockchain. Two blog posts

gion or on the basis of race, religion, etc. Hence, ethicalon May 15 describe its future activities in this area*39*40.

considerations must be taken into account. The same can

And it has published a white paper on DID*41. From thesebe said for the reputation mechanisms of real-world entities,

sources, it is apparent that the W3C DID is being used asa concern I also noted in relation to ERC-735 claims.

the ID space and that the Sidetree protocol developed by
the Decentralized Identity Foundation (DIF)*42 has been ad-

Thus, we now find ourselves in an age in which real-world

opted. This DID system is implemented on the second layer

entities are subject to being evaluated by various means.

of the Bitcoin blockchain, and source code has already been

From a management perspective, these measures may bereleased under the name ION (Identity Overlay Network)

necessary to ensure security, yet we still need a way to.

*43enable individuals to manage their own sensitive information
Finally, I will touch on credit scores and information banks.

based on the SSI concept. In particular, although it may

Some media reports claim services that calculate credit

not be easy to ask identity holders who have been issued ascores based on online activity are in the works in Japan

DID or claim for the first time to protect themselves in theas well. A concern is that only scoring done under the aus-

ways required, I think the ability to do this really is part ofpices of big-brother entities like GAFA and FAANG would be

the basic literacy we all need as denizens of the digital age.

considered accurate, and that your score could be passed
around without you intending it. As with AI, another talking

Some people have a desire to pass their social media ac-

point of late, there is a need to ensure transparency of notcounts to their children or grandchildren after they die, but

only the scoring system but the scoring algorithm as well.

this is becoming less and less advisable from a business*39

Microsoft Security Blog, “Decentralized identity and the path to digital privacy” (https://www.microsoft.com/security/blog/2019/05/15/decentralized-identity-digital-privacy/).

*40

Azure Active Directory Identity Blog, “Toward scalable decentralized identifier systems” (https://techcommunity.microsoft.com/t5/AzureActive-Directory-Identity/
Toward-scalable-decentralized-identifier-systems/ba-p/560168).

18

*41

Microsoft Whitepaper, Decentralized Identity—Own and control your identity (https://query.prod.cms.rt.microsoft.com/cms/api/am/binary/RE2DjfY).

*42

Decentralized Identity Foundation (DIF) (https://identity.foundation/) (https://github.com/decentralized-identity/).

*43

ION (Identity Overlay Network) (https://github.com/decentralized-identity/ion/).

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2. Focused Research (1)continuity perspective. With the advance of AI, it seems,

mechanisms for the Internet-based distribution of informa-

the temporary or permanent deactivation of accounts as antion (including sensitive information) linked to real-world

act of censorship against posted content is having a major

entities. But we face a large problem here. Privacy regula-

impact. I think these sorts of “everyday” examples are also

tions like the EU’s GDPR are not unique to the EU sphere.

a factor behind the rising call for services based on DID andCountries around the world, including Japan, are also sub-related technologies.

ject to such regulations. Hence, because the technologies
discussed here use blockchain and the circulation of cre-At present, I think a lot remains to be discussed in regard todentials is thus not limited to within any one region, use of

how we treat temporary IDs when it comes to handling mas-such technologies could face restrictions according to thesive quantities of statistical information and with respect

range of regulations that countries around the world have into cases in which credentials themselves are encrypted asplace. This is a far cry from the thinking behind cryptoassets​​

part of access control. A technology does not necessarilysuch as Bitcoin and Ethereum, and could be a major factor

gain traction just because the background technologies are

impeding the penetration of such technologies. The ERC-

compatible and it would have social applicability if deployed

725 Alliance and ID2020 will need to undertake activities

adroitly, and I have seen this many times over the years.

to dispel these impediments to cross-country distribution

At this juncture, it is uncertain whether the technologies I

mechanisms. At present, though, no such activities ap-

have discussed here will be deployed in applications users

pear to be underway. We need experts that can offer deep

identify with and be of any use to the world.

insights and broad perspectives to address these issues, including the issue of whether such problems should be dealt

With the advent of real use cases such as information banks,with by these consortiums in the first place.

people have come to realize the convenience provided by

Yuji Suga
Senior Engineer, Office of Emergency Response and Clearinghouse for Security Information, Advanced Security Division, IIJ. Dr. Suga has been in his current position since July
2008. He is engaged in investigation and research activities related to cryptography and information security as a whole. He heads up the CRYPTREC Operational Guidelines
Working Group on TLS Configuration and is a member of the CRYPTREC Cryptographic Technology Promotion Committee. He also serves as secretariat of the Cryptographic
protocol Evaluation toward Long-Lived Outstanding Security Consortium (CELLOS); secretary of the Information Processing Society of Japan’s Computer Security Group (CSEC);
assistant secretary of the ISEC Technical Committee of the Institute of Electronics, Information and Communication Engineers (IEICE); CyberSciTech2019 program co-chair;organizing committee member for IWSEC2019; and member of the Cryptoassets Governance Task Force (CGTF) Security Working Group.

© Internet Initiative Japan Inc.

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3. Focused Research (2)IIJ’s eSIM Initiatives

3.1 What is an eSIM?

using RSP. They were developed because a mechanism foreSIM has become an oft-heard keyword ever since the iPhone

installing profiles over a network was required for SIMs used

XS was announced in September 2018. Here, we provide

in embedded applications.

a technical explanation of eSIM and go over IIJ’s initiatives
in this area.

Some embedded applications employ SIM chips that are
soldered directly to the circuit board instead of the more

Traditional SIM cards consist of the following and are pro-common card-type SIMs. The following advantages of SIM

duced in tamper-resistant packages.

chips explain why.

• Subscription Data for the mobile service• Targeted at industrial equipment and thus offer high• Applets for valued-added services

durability• Secure storage for the subscription data and applets• A processor that performs authentication, encryption key generation, etc.

• Soldered to the board and thus resilient to the loosening of connections caused by vibration• Soldered to the board during manufacturing, thus
obviating the SIM insertion process

Of particular note, authentication and encryption keys them-• Small size enables device miniaturization

selves cannot be read off of the SIM.
To take advantage of these benefits, IIJ added SIM chips toWith eSIM, on the other hand, these elements are split into

its full MVNO SIM lineup in February 2019.

two parts: the profile, which contains the data and applets,
and the eSIM card, which contains the storage and pro-

Although SIM chips offer such advantages, it is virtually im-

cessor. In addition, the profile can be installed on the eSIM

possible to change the SIM once it has been embedded into

card from a dedicated server over a network. The speci-

the device during the manufacturing process. This means

fication was developed by GSMA*1. The mechanism forthat the SIM’s mobile line needs to be determined at manu-

installing a profile via a network is called RSP (Remote SIM

facture, which raises the following problems.

Provisioning). RSP itself is also used with traditional SIMs asa means of remotely changing data on the SIM using OTA(Over-the-Air) technology. As a full MVNO, IIJ also uses
OTA to write phone numbers to some SIMs when activating
the lines.

• Inability to standardize inventory of products for different export destinations• An active phone line needs to be used to check operating status at the time of manufacture• Mobile line cannot be switched even if the location

The term eSIM stands for embedded subscriber identifier
module, or embedded SIM. At present, it mostly refers toSIMs to which profiles can be installed over a network*1

where the product is used changes• Mobile line cannot be switched to, e.g., reduce communication costs

Short for the GSM Association, an industry group that represents mobile operators. Formed in 1995 to promote the spread of the GSM 2G standard. It is the largest
group in the industry, encompassing over 1,000 companies across 220 countries, including around 800 mobile operators. Also known as the organizer of Mobile
World Congress (MWC), the world’s largest exhibition for the mobile industry, held every February.

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3. Focused Research (2)While the use of SIM cards solves these problems, there

The ISD-R*2 is a direct interface between the inside andare on-site work costs associated with swapping out cards.

the outside of an eSIM and is what manages the eSIM.
Operations like downloading a profile, installing a down-

So eSIMs were developed to solve the above problems. The

loaded profile, and switching to or deleting an installed

profile can be installed after manufacture, eliminating the

profile are all performed via the ISD-R.

need for a mobile line contract to be set up when the SIM isembedded. Because profiles can be installed remotely, there

The ISD-P*3 is the equivalent of a traditional SIM card and isare no on-site costs associated with exchanging SIMs.

created for each installed profile. Profiles downloaded fromservers are formatted so as to describe the procedure for

3.2 How eSIM Works

creating the ISD-P. The profile is interpreted during instal-

3.2.1 eSIM Internal Structure

lation to create the ISD-P. Once the ISD-P to be used for

Figure 1 depicts the internal structure of an eSIM. Among

communications is activated, the eSIM looks like a normal

the elements shown, ISD-R, ISD-P, and ECASD are what

SIM from the device’s perspective.

characterize eSIMs.

Figure 1: Internal Structure of an eSIM

*2

ISD-R: Issuer Security Domain Root

*3

ISD-P: Issuer Security Domain Profile© Internet Initiative Japan Inc.

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The ECASD*4 stores the keys used in protecting the data

To obtain a GSMA signature, suppliers need to obtain SAS

when downloading a profile. A stored key is used for au-

accreditation for each of their eSIM production sites andthentication between the server and the eSIM card. A stored

profile storing server sites. Because of the high cost of

key is also used to decrypt the downloaded profiles, which

SAS accreditation, accredited eSIM production and server

are encrypted by the server.

sites are limited in number. In most cases, operators do nothave their own servers but instead use the services of SAS-The data protection keys stored in the ECASD are signed

accredited suppliers.

using Public Key Infrastructure, and a similarly signed key
is stored on the server side. To ensure SIM security, GSMA

As of June 2019, there are broadly two specifications forsigns these keys as the root certificate authority, and keys

eSIMs that support the remote intallation of profiles in thissigned by other certificate authorities are treated as invalid.

manner.

Figure 2: The M2M Model Interface*4

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3. Focused Research (2)■ The M2M model

The eSIM card communicates with the SM-SR server di-

Under this standard developed for M2M devices, eSIMs arerectly, and only SMS and packets are transferred on thecontrolled remotely. It is aimed at embedded devices, thedevice in which the eSIM card is embedded. The device

original purpose of eSIMs.

itself does not need much in the way of functionality; anordinary modem of recent incarnation is generally fine.

■ The Consumer model

The specification is geared to environments where only

Under this standard developed for end user-managed

limited functionality can be implemented, like embedded

devices, eSIMs are controlled via the device. The spec-

devices.

ification improves on parts of the M2M model that are
difficult to deal with when it comes to end user-managed

Since the SM-SR server controls the eSIM card in the M2M

devices.

model, the eSIM card only communicates with a specific
SM-SR server. Since they are set up to only communicate

3.2.2 The M2M Modelwith a specific SM-SR server, the platform operator that

The M2M model was the first eSIM specification developed.

manages the SM-SR server also supplies the physical eSIM

Since it is aimed at IoT devices, it allows profiles to be in-card. And since all profiles are installed via the SM-SR server,

stalled, switched, and deleted remotely. Figure 2 shows thethe platform operator that manages the SM-SR server also

elements of the M2M model. The main ones are as follows.

obtains the profiles to be installed. Hence, profile choices
depend on the platform operator.

• eSIM card
• Device with an embedded eSIM card

Communication between the eSIM card and SM-SR server• SM-SR*5 server for secure routing to the eSIM card

uses the IP protocol, but SMS is first used to trigger eSIM

• SM-DP

access by the SM-SR server. A mobile line is needed to send

*6

server to provide profiles

SMS messages, so eSIM cards that use the M2M model
In the M2M model, control of the eSIM card revolves aroundhave a factory-installed profile called the bootstrap. Since

the SM-SR server. An SMS is sent from the SM-SR server

all eSIM operations are performed remotely, bootstrappingto the eSIM card, a secure route between the SM-SR server

requires connectivity in all countries, so one challenge isand the eSIM card is opened, and the following operations

how to obtain this profile. Also, bootstrapping is unneces-are performed.

sary in cases where profiles do not need to be switched.
There is no need to replace profiles in products used only in• Profile download and installation

the domestic market, so traditional SIM chips are generally• Profile switchingfine in this case.

• Profile deletion*5

SM-SR: Subscription Manager - Secure Routing*6

SM-DP: Subscription Manager - Data Preparation© Internet Initiative Japan Inc.

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3.2.3 The Consumer Modelcalled the LPA manages profiles on the device. Another ad-

The Consumer model specification was developed following

dition is the SM-DS server, which is not present in the M2M

the M2M model. It is aimed at end user-operated devices,model. And because the SM-DP server has been modified

such as smartphones, and enables all eSIM operations to be

to meet requirements for consumer devices, it is called theperformed on the device. Figure 3 shows the elements of

SM-DP+ in this model.

the Consumer model. The main ones are as follows.
The LPA, added in the Consumer model, provides an inter• eSIM card

face to enable end users to do the following on the device.

• Device with an embedded eSIM card
• LPA*7 for managing the eSIM card on the device• SM-DP+ server, which provides the profile• SM-DS*8 server, which searches for profiles provided to the eSIM

• Enter the address of the SM-DP+ server where theprofile is stored and the profile identifier• Download profiles and install them on the eSIM chip
• Switch profiles• Delete unnecessary profiles

Unlike the M2M model, there is no SM-SR server for managing eSIM card profiles remotely. Instead, an application

Figure 3: The Consumer Model Interface

24*7

LPA: Local Profile Assistant*8

SM-DS: Subscription Manager - Discovery Server© Internet Initiative Japan Inc.

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3. Focused Research (2)Two implementations for the LPA are defined: LPAd, where

3.3 Moves by Major Vendors

the LPA runs in the device, and LPAe, where it runs in the

3.3.1 AppleeSIM card. When device vendors develop Consumer modelApple was an early mover in this space, providing eS-

eSIM devices, they need to choose whether to use an eSIM

IM-like functionality in the form of its Apple SIM. Details

that supports LPAe or to implement LPAd on the device.

of Apple SIM are not public, but it is thought to employ an

Because LPAe compatible eSIMs are not yet widespread,M2M-model eSIM. Yet it is very much a custom service;device vendors need to implement LPAd, so this is one hur-for example, because end users each enter into their own

dle to clear when developing Consumer model devices atphone line contracts, it incorporates a mechanism for acti-

present.

vating mobile services via the device. Although Apple only
provides the platform, the strength of its brand has seen it

With this model, everything is done on the device by the

successfully obtain profiles from mobile operators in many

LPA, so SMS is not needed the way it was in the SMS

countries.

model. And since profiles can also be downloaded via WiFi, there is no need for something like the M2M model’s

A feature of the Apple SIM is that it offers users worldwide

bootstrap profile. Because no extra mobile contracts are re-connectivity in a single SIM card. That said, only data plans,quired, LPA is also implemented and the Consumer model

not voice call contracts, are available with an Apple SIM.

adopted for IoT devices in some cases. On the other hand,

Possibly this comes down to voice contracts requiring morein the interests of end user convenience, some eSIMs arein the way of identity checks than data contracts and the

supplied with a mobile line profile installed so as to enable

varying regulations from country to country making it diffi-

the downloading of profiles.

cult to provide a solution within a single platform.

To install a profile, the following must be passed into theApple has continued to use the Apple SIM for the iPad but

LPA: the SM-DP+ server address and a Matching ID to iden-

adopted a standard consumer-model eSIM for the iPhone

tify the profile to be installed. A string called an activation

XS, released in 2018, probably because it was not possible

code (like the one below) is used to do this.

to uncouple the iPhone, which is a phone after all, fromvoice contracts. Given that the Apple SIM is still used on

1$SM-DP-PLUS.EXAMPLE.COM$MY-MATCHING-ID-0123456789

non-voice devices like iPads released after the eSIM-compatible iPhone XS, it would seem that Apple has only given

The string consists of the version number (currently fixed atup on voice contracts being provided via the Apple SIM. The“1”), SM-DP+ server address, and Matching ID, delimited

reasoning behind the decision was probably that adopting

by a “$” character. Entering these strings by hand is diffi-

a standard eSIM would mean that mobile operators create

cult, so they are usually converted to a QR code and readthe platform, making it possible to meet the voice contract

into the device (Figure 4).

regulations.
With the Apple SIM, the contracts went through Apple,
which made it difficult for an MVNO like IIJ to offer services. With the consumer-model eSIM on the iPhone XS
and later models, there are no limitations on the profiles
installed, so IIJ’s full MVNO profile fits the bill. Users of theiPhone XS/XR are one major target of the IIJ eSIM services.
3.3.2 Microsoft
Microsoft included a standard LPA in Windows 10 version
1703, probably because it believes that eSIMs will be usefulin realizing its Always-Connected PC concept. The inclusionof an LPA service in the OS obviates the need for device

Figure 4: An Activation Code in QR Code Form

vendors to implement their own LPA, meaning it is now© Internet Initiative Japan Inc.

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easy for vendors to make eSIM-compatible devices so long

the world. Yet while it is limited to US residents, it does pro-as they obtain eSIM cards and compatible modem modules.

vide voice services, unlike with the Apple SIM. Google was

So we can expect this simplification of device manufactur-

probably able to achieve this because it provides the service

ing to help fuel the spread of eSIM-equipped devices ahead.

as an MVNO and because it zeroed in on US-resident users,

One sign of this is that Microsoft itself has released eS-

so that it only had to deal with the US regulations relating toIM-equipped Surface Pros.

end-user voice services.

Microsoft also provides an app called Mobile Plans that lets

3.3.4 Similar Services

users sign up for mobile plans via their device, like with the

While not the same as eSIM, some vendors are selling pro-Apple SIM. In Japan as of June 2019, profiles can be pur-files based on proprietary specifications, mainly in Greaterchased from KDDI, GigSky World Mobile Data, and Ubigi.

China. They provide a proprietary SIM along with an OTA
service for installing profiles on the SIM, allowing end

On another front, at Microsoft Ignite 2018, held at end-No-

users to download and use profiles from mobile operators

vember 2018 in the US, Microsoft revealed plans to integrate

in a wide range of countries. Outbound travelers are the

eSIM support into enterprise MDM*9. Enterprise customers

end-user target group, and the objective is to provide lessneed device management for their PCs, and bringing theexpensive connectivity on the road than roaming services.

management of mobile subscriptions into the MDM fold will

An example of this type of service in Japan is the Henn nagive enterprise device managers control over the eSIM pro-

SIM series sold by H.I.S. Mobile.

files used in their devices as well.
With the appearance of eSIM-equipped devices like the3.3.3 Google

iPhone XS, though, these services also seem to be transi-

Google seems to be lagging Apple and Microsoft when ittioning away from proprietary specifications to open eSIM

comes to eSIM support. Although it defined APIs related toplatforms.

eSIM in Android Pie, the OS itself does not have LPA functionality, so each vendor needs to implement an LPA app.

3.4 IIJ’s Initiatives

Google itself does offer eSIM-compatible, LPA-equipped de-

As a full MVNO operator, IIJ can provide its own profiles forvices like the Pixel 2, Pixel 3 and Pixel 3a. But as of thisinstallation on eSIMs. We have already launched an eSIM

writing in June 2019, the devices sold in the Japanese mar-service providing our full MVNO profiles as one of our full

ket are equipped with NFC*10 instead of eSIM support, so it

MVNO service sales channels.

looks like Japanese users are unable to use an eSIM withthese Google offerings.

As discussed, eSIMs come in two forms: the M2M modeland the Consumer model. IIJ has started targeting the26

Google has launched its own eSIM-based MVNO service

Consumer model first with its eSIM services. The reason

called Google Fi, providing connectivity around the world.

for this is that because IIJ’s own profiles only provide con-

While the range of supported Android devices is limited, thenectivity in Japan, we believe the Consumer model is more

iPhone is also supported. Given that the service is available

suitable for our full MVNO services than the M2M model,

for devices Google itself does not manage, like the iPhone,which is geared to overseas deployment. Additionally,

one can infer that it uses consumer-model, rather thanit can be difficult to ensure connectivity outside of theM2M-model, profiles. However, the service is only available

Japanese market with full MVNO profiles, and they cannot

to US residents; access does not extend to end users aroundbe used to bootstrap.

*9

MDM: Mobile Device Management*10

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3. Focused Research (2)Last year, we carried out PoC testing based on the Consumer

3.5 eSIM Use Cases and Future Trends

model as part of our efforts to get eSIM services off theWhat does the future have in store for eSIM usage?

ground. In the PoC, we installed the our full MVNO profile ina Microsoft Surface Pro LTE Advanced and accessed to the

The big difference between eSIMs and traditional SIMs is theInternet with the profile successfully. We are also testing theelimination of the physical SIM. Eliminating the physical card

operation of other target devices and building up our knowl-and handling profiles as electronic data obviates SIM cardedge base. One thing we learned is that compatibility issuesdelivery costs (not only money but distance and time). Therebetween profiles and eSIM cards can arise. As described

is a tendency to focus on price when it comes to costs, butearlier, eSIM card profiles have a specific format. A tem-with eSIMs, there is no need to travel to a store or wait forplate notation is defined to simplify the profile descriptors,

a SIM to be delivered. This means end users can purchase

but we discovered that certain patterns result in installation

profiles anytime, wherever they need them. Long-term con-errors with certain eSIM cards. We also discovered installa-

tracts may not play to this benefit, but it makes purchasingtion problems triggered by the absence of certain optional

prepaid contracts easier, especially for travelers looking toparameters in the profiles. Unlike the M2M model, which

temporarily make use of services at their destination. Plus,

assumes control over the eSIM card, the Consumer model

there is no need to swap out physical SIM cards, the advan-

targets a wide range of eSIM cards, so building this sort oftages of which include mitigating the risk of loss. And withknowhow is crucial to providing services under this model.

DSDS*11 devices like the iPhone XS, the main voice contract
SIM card can go in the SIM slot while prepaid data SIMs can

On July 18, 2019, we commercially launched our eSIM

be purchased as and when needed. But within the context

Plan (beta version). Unlike eSIM services offered in Japanof the Japanese market, fully adopting eSIMs and the high(Docomo’s dtab, KDDI’s prepaid plans for Windows), ourdegree of mobility they afford consumers would not be di-service is broadly available and not restricted to a particular

rectly beneficial to the mobile operators. So it is difficult to

subset of devices. Building our own SM-DP+ server is notsee eSIMs gaining traction unless device makers take themuch of an option since it would require SAS accreditation

lead in offering SIM-free devices. By making eSIM services

from the GSMA, so we will use other companies’ services

available as soon as possible, IIJ hopes to set the stage forlike other mobile operators do.

device makers to roll out eSIM-compatible devices.

Daisuke Maruyama
MVNO Service Development Section, Technology Development Department, MVNO Division
Mr. Maruyama joined IIJ in 2018. He is working on the development of service infrastructure for full MVNO services. Most recently, he has
been developing eSIM service infrastructure of the type discussed in this volume.

*11

DSDS: Dual SIM Dual Standby© Internet Initiative Japan Inc.

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September 2019 Vol.
About Internet Initiative Japan Inc. (IIJ)
IIJ was established in 1992, mainly by a group of engineers who
had been involved in research and development activities related
to the Internet, under the concept of promoting the widespreaduse of the Internet in Japan.
IIJ currently operates one of the largest Internet backbones
in Japan, manages Internet infrastructures, and provides
comprehensive high-quality system environments (includingInternet access, systems integration, and outsourcing services,etc.) to high-end business users including the government andother public offices and financial institutions.
In addition, IIJ actively shares knowledge accumulated throughservice development and Internet backbone operation, andis making efforts to expand the Internet used as a social
infrastructure.­­The copyright of this document remains in Internet Initiative Japan Inc.
(“IIJ”) and the document is protected under the Copyright Law of Japanand treaty provisions. You are prohibited to reproduce, modify, or makethe public transmission of or otherwise whole or a part of this document
without IIJ’s prior written permission. Although the content of thisdocument is paid careful attention to, IIJ does not warrant the accuracy andusefulness of the information in this document.
Initiative Japan Inc. All rights reserved.
© Internet
IIJ-MKTG020-0041

Internet Initiative Japan Inc.
Address: Iidabashi Grand Bloom, 2-10-2 Fujimi, Chiyoda-ku,
Tokyo 102-0071, Japan
Email: info@iij.ad.jp URL: https://www.iij.ad.jp/en/