Page 23 - ITU Journal - ICT Discoveries - Volume 1, No. 2, December 2018 - Second special issue on Data for Good

ITU JOURNAL: ICT Discoveries, Vol. 1(2), December 2018

AN INTERNET OF BLOCK THINGS

Phillip H. Griffin
Griffin Information Security, United States

Abstract – This paper defines extensible, distributed blocks of hash-linked data constructed using the
cryptographic message syntax (CMS) SignedData message. The described SignedData blockchain allows
each block to reside in a different physical location on the Internet of things (IoT). Each signed, time-
stamped block content can combine data from multiple locations that are ‘detached’ from and remote to
its block header. Two types of SignedData sidechains are described, ephemeral and fixed. Ephemeral
sidechains can be added to any block at any time without affecting the integrity of the blockchain. They
can also be removed without disruption, making them ideal for use in applications that must manage
limited storage capacity or comply with right-to-be-forgotten privacy regulations. A simple blockchain
example is presented using CMS SignedData for its block content and headers. This example is then
extended to create doubly-linked blockchains and blockchain grids.

Keywords – ASN.1, blockchain, IoT, sidechain, SignedData

1. INTRODUCTION CMS is a mature schema that has been in use for
over twenty-five years and employed in a broad
A blockchain can be described as a distributed range of applications. CMS messages have been
series of signed, hash-linked, append only, standardized as "RSA Public Key Cryptography
timestamped sets of data, grouped into blocks. Standard (PKCS) #7, the Secure Electronic Mail
When viewed as an abstract data type, a blockchain (S/MIME) CMS standard defined by the Internet
is a limited stack implemented as a hash-linked list Engineering Task Force (IETF), and the X9.73
whose sole operation allows users to push blocks Cryptographic Message Syntax" [3] used in the
onto the top. Users may not modify the data financial services. A new international version of
content of any block or pop blocks off of the stack CMS has been developed in ITU-T Study Group 17
without detection, since any changes made to the (SG17) and will be published as Recommendation
content or its hash would compromise the integrity X.894.
of its hash-linked blocks.
The attributes defined later in this paper and those
The SignedData message data type defined in the referenced from CMS standards rely on the ASN.1
cryptographic message syntax (CMS) standard can schema specified in the ITU-T X.500-series of
be used to create extensible, distributed Recommendations (The Directory standards). CMS
blockchains. CMS is a widely implemented key attributes are compatible with those implemented
management standard whose messages are in many authentication and identity management
defined using Abstract Syntax Notation One (ASN.1) systems. The SignedData blockchain schema
[1]. ASN.1 is a schema definition language defined defined in this paper with ASN.1 can be input to
in a series of international standards maintained tools that generate programming language code.
jointly by ISO/IEC and ITU-T [2]. This code can be used to exchange information on
a wide range of platforms without consideration of
specific programming language, hardware, or
operating system characteristics.

© International Telecommunication Union, 2018 1