Network Working Group M. Sato
Internet-Draft M. Shimaoka
Intended status: Informational SECOM IS Lab.
Expires: January 3, 2019 H. Nakajima, Ed.
Mercari R4D
July 2, 2018

General Security Considerations for Crypto Asset Exchange


This document discusses the threat, risk, and controls on the followings; Online system of crypto asset exchange that provides the exchange service to its customer (consumers and trade partners); asset information (including the private key of the crypto asset) that the online system of a crypto asset exchange manages; Social impact that can arise from the discrepancy in the security measures that are implemented in the online system of a crypto asset exchange.

This document is applicable to the crypto asset exchanges that manages the private key that corresponds to crypto asset. It includes the organizations that outsources the key management to another organization. In such a case, the certain recommendations applies to those outsourcers.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

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This Internet-Draft will expire on January 3, 2019.

Copyright Notice

Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1. Introduction


2. Scope of this document

In this document, crypto asset exchange operators which hold a private key of crypto asset.

3. Conventions and Definitions

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

4. Terminology

Terms used in this document are defined in other i-d.

5. Basic description of a model online system of a crypto asset exchange

5.1. General

In this section, a model online system of a crypto asset exchange that is used to explain the concepts and provisions in this document are explained.

5.2. A basic model of online system of a crypto asset exchange and its functional components

Followings are the basic model of a crypto asset exchange that this document deals with.

5.3. The flow leading to the sending of the transaction

5.4. Types of keys that are used for signature and encryption

5.4.1. Type of keys

5.4.2. A flow for the key generation and the key usage

5.4.3. On the usage of multiple keys

5.4.4. On the suspension of keys

5.5. On the characteristics of crypto asset on Blockchain and distributed ledger technologies

5.5.1. General

5.5.2. The importance of the private key used for signing

5.5.3. Diversity of implementations On the cryptographic algorithms used by crypto asset On the possibility of the forking of the Blockchain Rollback by reorganization The treatment of the forked crypto asset

5.5.4. Risk on the unapproved transactions General The handling of the unapproved transactions Transaction failures caused by the vulnerabilities of the implementation or the specification of the crypto asset

6. Basic objectives for the security management of crypto asset exchanges

7. Approaches to basic security controls

8. Sector specific security management controls for crypto asset exchanges

8.1. General

8.2. On the direction of the information security management

8.3. On the controls for key recovery

8.4. On the controls against theft and leakage of the private key for signing

8.5. On the illegal operation of the private key for signing

8.6. On the illegal operation against the asset data

8.7. On the user authentication

8.8. On the withdrawal of the coins

8.9. On the transfer of the crypto asset to an unused address

9. Remaining issues

10. Security Considerations

Security Considerations are included in main section of this document.

11. IANA Considerations


12. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.

Appendix A. Contributors

Authors' Addresses

Masashi Sato SECOM Co., Ltd. Intelligent System Laboratory SECOM SC Center 8-10-16 Shimorenjaku Mitaka, Tokyo, 181-8528 JAPAN EMail:
Masaki Shimaoka SECOM Co., Ltd. Intelligent System Laboratory SECOM SC Center 8-10-16 Shimorenjaku Mitaka, Tokyo, 181-8528 JAPAN EMail:
Hirotaka Nakajima (editor) Mercari, Inc. R4D Roppongi Hills Mori Tower 18F 6-10-1 Roppongi Minato, Tokyo, 106-6118 JAPAN EMail: