Publication Date: 2018-10-09

Approval Date: 2018-06-07

Submission Date: 2018-07-05

Reference number of this document: OGC 18-041r1

Reference URL for this document: http://www.opengis.net/doc/DP/dlt-blockchain-review

Category: Discussion Paper

Editor: Gobe Hobona, Bart De Lathouwer

Title: Geospatial Standardization of Distributed Ledger Technologies

OGC Discussion Paper

COPYRIGHT

Copyright © 2018 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/

WARNING

This document is not an OGC Standard. This document is an OGC Discussion Paper and is not an official position of the OGC membership. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an OGC Standard. Further, any OGC Discussion Paper should not be referenced as required or mandatory technology in procurements. However, the discussions in this document could very well lead to the definition of an OGC Standard.

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1. Summary

Trust is a key requirement of the modern-day digital economy. In most current applications, trust is delegated out to a third-party who acts as a type of Trust Authority. This provides a degree of assurance to participating applications because they can verify information through the Trust Authority. Dependency on a centralized trust authority however carries some risk, should the centralized trust authority become compromised and suddenly become unavailable. To address this risk, a new trust paradigm based on Distributed Ledgers has recently emerged.

Distributed Ledgers are collections of replicated, shared and synchronized digital records that are stored across multiple sites that are geographically spread. The technologies used to implement such ledgers are referred to as Distributed Ledger Technologies (DLT). An example of a DLT is blockchain, which is a digital ledger of records arranged into linked chunks of data called blocks. The blocks are linked together through a hashing function that provides cryptographic validation on those records.

By far, the most widely cited application of blockchain is in the finance sector where it can be used as a cryptocurrency as shown by Bitcoin and Ethereum. However, other application areas are gaining popularity too, demonstrating the utility of blockchain in non-financial sectors. Blockchain has been used in a variety of applications, for example cryptocurrencies, land registration, and justice. In each of these application areas, location can play a key role. For example, the location of transactions can determine what taxes apply, the location of the boundary of a property forms the basis of its registration, and the location where evidence is discovered in a crime scene can have an impact on judicial proceedings.

Recognizing the role that location can play in applications of blockchain, the Open Geospatial Consortium (OGC) initiated a review of DLT and blockchain. The review was initiated within the OGC Technology Trends activity, which has been set up to continuously provide analysis of technology trends and advise on their potential impact of current and future OGC standards. This document is a Discussion Paper on geospatial standardization of distributed ledger technologies, including blockchain. The purpose of the Discussion Paper is to improve the OGC’s understanding of blockchain and distributed ledger technologies, and thus inform future OGC activities.

1.1. Requirements & Research Motivation

The review of blockchain and DLT was tasked to consider the following.

  • What are DLT?

  • What is blockchain?

  • What standardization initiatives exist related to blockchain?

  • What should OGC do next?

1.2. Prior-After Comparison

At present none of the OGC working groups have explored blockchain. Similarly, blockchain and other DLT have not been explored within the OGC testbed series. It is envisaged that after consideration of this discussion paper, OGC working groups will begin to consider the nature of geospatial standardization required for DLT.

1.3. Recommendations for Future Work

This discussion paper makes the following Recommendations.

  1. OGC should establish a Distributed Ledger Technology Domain Working Group (DWG) to help define future requirements for geospatial standardization of DLT (including blockchain) and maintain liaison with the International Organization for standardization (ISO) and other standards development organizations.

  2. OGC should establish a Standards Working Group (SWG) to support the progression of the Crypto-Spatial Coordinates (CSC) specification towards becoming an OGC standard.

  3. OGC should establish a SWG to progress the FOAM open protocol towards becoming an OGC standard.

  4. A future Distributed Ledger Technology DWG should work alongside or within the Security DWG. Before implementing these recommendations, there should be further discussion in the Technical Committee.

Note
 DWG provide a forum for discussion of key interoperability requirements and issues, discussion and review of implementation specifications, and presentations on key technology areas relevant to solving geospatial interoperability issues. In contrast, SWG have specific charter of working on a candidate standard prior to approval as an OGC standard or on making revisions to an existing OGC standard.

1.4. Document contributor contact points

All questions regarding this document should be directed to the editor or the contributors:

Contacts

Name Organization

Gobe Hobona

Open Geospatial Consortium

Bart De Lathouwer

Open Geospatial Consortium

Manohar Velpuri

International Federation of Surveyors

Kristoffer Josefsson

FOAM

1.5. Foreword

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.

Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.

2. References

The following normative documents are referenced in this document.

3. Terms and definitions

For the purposes of this report, the definitions specified in Clause 4 of the OWS Common Implementation Standard OGC 06-121r9 shall apply. In addition, the following terms and definitions apply.

3.1. blockchain

A digital ledger of records arranged into linked chunks of data called blocks, that are associated together through a hashing function that provides cryptographic validation on those records.

3.2. distributed ledger

A collection of replicated, shared and synchronized digital records that are stored across multiple sites that are geographically spread.

3.3. feature

Abstraction of real world phenomena.

3.4. observation

Act of measuring or otherwise determining the value of a property (ISO 19156:2011).

3.5. sensor

An entity capable of observing a phenomenon and returning an observed value. Type of observation procedure that provides the estimated value of an observed property at its output. Note: A sensor uses a combination of physical, chemical or biological means in order to estimate the underlying observed property. At the end of the measuring chain electronic devices often produce signals to be processed (OGC 12-006).

3.6. hash function

A function which maps strings of bits of variable (but usually upper bounded) length to fixed-length strings of bits, satisfying the following two properties: (1)for a given output, it is computationally infeasible to find an input which maps to this output; (2) for a given input, it is computationally infeasible to find a second input which maps to the same output (ISO/IEC 10118-1:2016)

3.7. register

A set of records with assigned identifiers and describing items of a particular type.

3.8. registry

An information system that hosts one or more registers and allows those registers to be accessed, reviewed and maintained.

3.9. Abbreviated terms

  • CSC Crypto-Spatial Coordinates

  • DGGS Discrete Global Grid Systems

  • DLT Distributed Ledger Technologies

  • GML Geography Markup Language

  • SOS Sensor Observation Service

  • SPS Sensor Planning Service

  • WKB Well Known Binary

  • WKT Well Known Text

4. Overview

This discussion paper is organized as follows.

  • Background: This section introduces DLT and blockchain, as well as the structure of blocks.

  • Case Studies: This section presents an overview of example projects that use or are studying blockchain within a geospatial context.

  • Current Standardization Initiatives: This section presents an overview of a selection of standardization initiatives involving blockchain and geospatial data.

5. Background

DLT are database software that enable the creation and maintenance of geographically spread collections of replicated, shared, and synchronized digital records. By virtue of being distributed, DLT allow the information in a ledger to be replicated across a network thus making it easier to detect modifications made to the data at any node on the network. This is in contrast to centralized ledgers which store data at a single node on the network. Illustrations of the topologies of centralized and distributed ledgers are shown in Figure 1.

img topology
Figure 1. Illustrations of the topologies of centralized (left) and distributed (right) ledgers

The centralized ledger, depicted on the left of Figure 1, has all nodes in the network depending on the central node (marked with a 'C') for storage of the data. The distributed ledger, in contrast, allows the data to be replicated at all nodes on the network. Therefore there is no dependency on any single node within the distributed ledger network.

Blockchain can be described as a continuously growing collection of records organized into blocks that are securely linked through cryptographic means. The blocks are linked together through a hash function that provides cryptographic validation on those records. An illustration of a blockchain as it grows over time is presented in Figure 2.

img blockchain
Figure 2. High-Level overview of a blockchain

The anatomy of a block resembles that of other binary formats. A block consists of an indicator of the block size, a block header, transaction counter and the series of transactions contained in the block [1]. Table 1 presents a description of these fields.

Table 1. Structure of a block
Size (bytes) Field Description

4

Block size

The size of the block

80

Block header

Formed of several fields, including metadata

1-9

Transaction counter

Indicates how many transactions are to follow

Variable

Transactions

The actual transactions contained in the block

Note that the structure of a block allows a block to hold any number of transactions, provided that the number of transactions is stated in the transaction counter. Note as well that the block can be of any size, provided that the size is specified in the block size field.

The block header contains metadata for identifying and validating the block. This includes a hash of the previous block, the merkle root, the timestamp, the proof-of-work algorithm difficulty target, and the nonce. Table 2 presents a description of this metadata. The merkle root is the hash of all of the hashes of all of the transactions in the block. The proof-of-work algorithm provides the means to solve the mathematical problem used to determine the sequence in which the blocks should be arranged.

Table 2. Block header metadata
Size (bytes) Field Description

4

Version

A software version number

32

Previous block hash

A reference to the parent block in the chain

32

Merkle root

A hash of the root of the merkle tree of the transactions of this block

4

Timestamp

The approximate creation time on this block

4

Difficulty target

The Proof-of-Work algorithm difficulty target for this block

4

Nonce

A counter used for the PoW algorithm

Despite location potentially having a role in many blockchain applications, there does not seem to be a standard way to represent location within transactions or other block header metadata. This creates an impediment to interoperability between different blockchain-based systems, at least in as far as their potential to share geospatially-referenced information.

6. Case Studies

This section presents an overview of a selection of geospatial-related initiatives that have either implemented solutions that use blockchain, or are studying the potential application of blockchain.

6.1. Land Registration

The Land Registry of Sweden (Lantmäteriet) commissioned a study of the possibilities of using blockchains as a technical solution for real estate transactions [2]. Lantmäteriet sought to reduce the problems and issues affecting the current land registration process. The study found that the time between writing the purchasing contract and registering the title with Lantmäteriet could be reduced from four months to a few days through the use of a blockchain-based approach. It is foreseeable that in the future the process could eventually take place in near real time. The study also found that a blockchain-based solution would increase confidence in the land registration system since manipulation of the system would be more difficult, as all of the information would be replicated, shared, and verified across the network. The risk of errors and fraud would be reduced because digital signatures are provided at several instances.

Other national land registries that are reported to be experimenting with blockchain include the Rwanda Natural Resources Authority and Her Majesty’s Land Registry in the United Kingdom. It is foreseeable that other National Land Registries will also begin to experiment with blockchain in order to develop their own understanding and expertise in the technology.

6.2. Space

The United States National Aeronautics and Space Administration (NASA) is reported to be looking to use smart contracts on the Ethereum blockchain in the agency’s SensorWeb program [3]. The main objective of the NASA SensorWeb activity is to create an interoperable environment for a diverse set of Earth observing satellite sensors via the use of software and the Internet. The NASA SensorWeb uses the OGC Sensor Web Enablement (SWE) suite of standards including the OGC Sensor Observation Service (SOS) and Sensor Planning Service (SPS) standards [4]. SOS defines a Web service interface which allows querying observations, sensor metadata, as well as representations of observed features (OGC 12-006). SPS defines interfaces for queries that provide information about the capabilities of a sensor and how to task the sensor (OGC 09-000).

The European Space Agency (ESA) is also investigating the potential role of blockchain in implementing the Space 4.0 vision which represents the evolution of the space sector into a new era, that involves greater participation of the private sector, academia, and private citizens in Space activities [5]. The ESA project aims to establish what drives the value of blockchain technology, how blockchain itself works, what it can be used, and how it might be exploited by ESA.

6.3. City Services

The city council of Antwerp has set out a vision to use blockchain for the registration of citizens [6]. The blockchain-based system will allow every newborn child to be registered in a 'personal' blockchain. After initial registration, each milestone in the child’s life would be logged in the blockchain, thereby providing a log that can be verified and consulted. The system will offer citizens an automated service to support mobility, health, education and other city services. Localized experiments have already began to trial the system. Given that every birth occurs at a location and that most milestones in a citizen’s life occur at a location, it is clear that geospatial standards such as the Geography Markup Language (GML) could play a significant role in enabling interoperability between such city citizen registries. GML is an XML grammar for expressing geographical features (OGC 07-036r1).

6.4. Pan-Government Registries

One of the largest non-financial implementations of blockchain is the digital infrastructure of the government of Estonia [7]. The government of Estonia has integrated Keyless Signature Infrastructure (KSI) that is based on blockchain into key registries such as the business registry, health registry, property registry, succession registry, digital court files, and official announcements. The technology facilitates both internal and external processes in order to enable the efficient detection of modifications to data and maintain the integrity of records.

A key component of the Estonia government’s blockchain-based system is an interoperability platform called X-Road. The platform integrates different interfaces, security services, and serves as the technical backbone of the government’s digital infrastructure, thereby underpinning various public and private sector services. The main purpose of the X-Road platform is to connect different governmental institutions and to facilitate state governance via the use of digital technologies.

7. Current Standardization Initiatives

This section presents overviews of a number of standardization initiatives.

7.1. International Organization for Standardization (ISO)

In September 2016, the International Organization for Standardization (ISO) established technical committee ISO/TC 307 to develop new standards on blockchain [8]. Australia was tasked with managing this new technical committee. As at April 2017, the technical committee had more than 30 members including: United States, Germany, United Kingdom, Japan, France, China and many others. The current roadmap of the technical committee envisages delivery of the new standards by 2020. The technical committee has established working groups to cover terminology, reference architecture, taxonomy, ontology, use cases, security, privacy, identity, smart contracts and other topics.

Recognizing that the use of blockchain is continuing to grow, ISO/TC 211 the technical committee for geospatial information and geomatics established a liaison with ISO/TC 307. Given the close relationship between OGC and ISO/TC 211, which has led to OGC standards such as the GML becoming an ISO standard, it is evident that OGC should be engaging with both of these ISO technical committees on the subject of blockchain standardization.

7.2. International Federation of Surveyors (FIG)

Another international group looking into blockchain is the International Federation for Geomatics (FIG). FIG is an international organization established to provide a forum for discussion and development of surveying professional practice and standards. It covers the whole range of professional fields in surveying, geomatics, geodesy and geo-information communities. FIG Commission 9 on Valuation and the Management of Real Estate and FIG Commission 7 on Cadastre and Land Management are the two groups within FIG that are looking into implications of blockchain.

7.3. The World Bank

The World Bank published a financial technologies (FinTech) note that outlined the mechanisms, origins, characteristics, advantages, challenges, and risks of DLT [9]. The FinTech note also proposed next steps for the World Bank to study and evaluate areas where DLT could potentially be integrated into World Bank financial sector operations. Amongst the next steps, the FinTech note suggests the following action "Foster international co-operation and collaboration, leveraging ongoing participation in working groups of international standard setting bodies" [9].

Since publishing the FinTech note, the World Bank has continued to examine DLT and blockchain. For instance, in April 2018 the World Bank and the International Monetary Fund (IMF) jointly held a series of exchange workshops to explore applications, challenges and opportunities of new FinTech [1]. The workshops, which were titled FinTech Exchange, were held within the annual IMF/World Bank Spring meetings that bring together senior government officials, private sector executives, academics and central bank executives to discuss issues of global concern relating to economics, development and finance. Blockchain featured prominently in discussions at the FinTech Exchange.

7.4. Telecommunications sector of the International Telecommunication Union (ITU-T)

Another organization that is currently working on developing blockchain-related standards is the Telecommunications sector of the International Telecommunication Union (ITU-T). The organization has established three focus groups to work on blockchain-related standardization [2]. The focus groups include:

  • FG-DPM (Data Processing & Management)

  • FG-DLT (Distributed Ledger Technology)

  • FG-DFC (Digital Currency)

7.5. Potential Standards from FOAM

A potential standard relating to both blockchain and geospatial data is FOAM. The FOAM initiative is building a proof of location protocol that allows users and autonomous agents to privately record authenticated location data and reveal their personal information at their discretion, by presenting a location claim [10]. FOAM is an open source protocol for decentralized, geospatial data markets on the Ethereum blockchain. The protocol allows for interoperable verification of location, using tokens to create economic incentives for the validation of geospatial data.

The protocol consists of the FOAM Coordinate System, FOAM Verification Layer, and a Spatial Index. The FOAM Coordinate System acts as a registry of Crypto-Spatial Coordinates (CSC) that record geospatial data on the blockchain. The FOAM Verification Layer incentivizes users to build reputation around CSCs claims. The Spatial Index provides real-time visualization. CSC is organized as a separate specification, although it is used by the FOAM protocol. This separation potentially makes CSC reusable across a number of other protocols and standards.

There are at least two OGC standards that could potentially be applied within the CSC specification. CSC currently uses geohashes to represent geographic locations. A geohash is a short alphanumeric string for representing locations [11]. An alternative to using CSC, would be to use an OGC Discrete Global Grid System (DGGS). A DGGS is a form of Earth reference that represents the Earth with a tessellation of nested cells (OGC 15-104r5). The geohash used in CSC functions is encoded as a series of bytes. An alternative mechanism for representing locations would be to use the OGC/ISO Well Known Binary (WKB) standard which also represents locations as a series of bytes (OGC 06-103r4).

8. Conclusions

This discussion paper concludes that there is a need for geospatial standardization of blockchain and other distributed ledgers. The initial focus for standardization should be in how location is represented in blockchains. For this to be achieved, there are three routes. First, OGC should establish a DWG to help define future requirements for geospatial standardization of DLT (including blockchain) and maintain liaison with other standards development organizations such as ISO/TC 307 and industry associations such as FIG. Second, OGC should establish a SWG to support the progression of the CSC specification towards becoming an OGC standard. Third, OGC should establish a SWG to progress the FOAM open source protocol towards becoming an OGC standard. Finally, a future Distributed Ledger Technology DWG should work alongside or within the Security DWG. Before implementing these recommendations, there should be further discussion in the Technical Committee.

Appendix A: Ad-hoc session on "Geospatial Standardization for Distributed Ledgers"

The OGC held an ad-hoc session on "Geospatial Standardization for Distributed Ledgers" during the 106th Technical Committee meeting held in Orleans, France. The session was held on March 19th 2018 from 08:30hrs CET to 09:25hrs CET.

The session aimed to build understanding of the potential application of geospatial standards within distributed ledgers, as well as an understanding of how distributed ledger technologies could be used to enhance the capabilities of web services that are based on OGC standards.

Agenda

A non-technical introduction to blockchain by Bart De Lathouwer (OGC)

Standardization for Distributed Ledgers - Opportunities and Challenges by Prof. Manohar Velpuri (FIG, ISO TC307 and UNGGIM academic network)

Crypto-Spatial Coordinates and The Future of Proof of Location by Kristoffer Josefsson and Arthur Roing Baer (FOAM)

What next for OGC on Distributed Ledger Technologies? by Gobe Hobona (OGC)

Points Raised During the Session

Participants raised the following points during the session:

  • Blockchain appears to be partially orthogonal to some existing OGC standards. This makes it difficult to pinpoint exactly what OGC needs to do in this domain.

  • OGC needs to send a clear message to industry to say "if you want to encode geospatial information in blockchain, consider using OGC standards".

  • One of the OGC standards that could be used with blockchain is Well-Known Text (WKT) and its associated Well-Known Binary (WKB) standard (OGC 06-103r4).

  • There may not be a strong need for new standards in blockchain, however the nature of smart contracts is such that one cannot have too many standards on the blockchain.

  • The focus of the OGC may need to be in communication and education across industry.

Appendix B: Revision History

Table 3. Revision History
Date Editor Release Primary clauses modified Descriptions

Apr 12, 2018

G. Hobona

.1

all

Initial version

Apr 13, 2018

G. Hobona

.2

all

Revisions based on feedback from contributors

Apr 24, 2018

G. Hobona

.3

7

Revisions based on feedback from contributors

Apr 26, 2018

G. Hobona

.4

7

Revisions based on feedback from contributors

Jul 05, 2018

G. Hobona

.5

1.3,8

Revisions based on Fort Collins TC motion

Appendix C: Bibliography

  1. Antonopoulos, A.: Mastering Bitcoin: Unlocking digital crypto-currencies. O’Reilly (2014).

  2. Lantmäteriet, Telia, ChromaWay, Kairos Future: The Land Registry in the blockchain, http://ica-it.org/pdf/Blockchain_Landregistry_Report.pdf, (2016).

  3. Graham, K.: NASA to use blockchain tech in distributed spacecraft missions, http://www.digitaljournal.com/tech-and-science/technology/nasa-s-blockchain-tech-will-allow-unmanned-spacecraft-to-think/article/513781#ixzz5CS2pHLg9, (2018).

  4. Percivall, G.: OGC® SWE Implementation Maturity Engineering Report, https://portal.opengeospatial.org/files/?artifact_id=53823, (2013).

  5. ESA: Beyond Bitcoin: Leveraging the Blockchain for Space 4.0, https://www.esa.int/About_Us/Digital_Agenda/Beyond_Bitcoin_Leveraging_the_Blockchain_for_Space_4.0, (2017).

  6. Verhaert, R.: Blockchain, de overheid aan of in de ketting (Blockchain: the government on or in the chain). Vanden Broele (2016).

  7. Artinovic, I., Kello, L., Sluganovic, I.: Blockchains for Governmental Services: Design Principles, Applications, and Case Studies, https://www.ctga.ox.ac.uk/sites/default/files/ctga/documents/media/wp7_martinovickellosluganovic.pdf, (2017).

  8. Standards Australia: Roadmap for Blockchain Standards, https://www.standards.org.au/getmedia/ad5d74db-8da9-4685-b171-90142ee0a2e1/Roadmap_for_Blockchain_Standards_report.pdf.aspx, (2017).

  9. World Bank Group: Distributed Ledger Technology (DLT) and Blockchain, http://documents.worldbank.org/curated/en/177911513714062215/pdf/122140-WP-PUBLIC-Distributed-Ledger-Technology-and-Blockchain-Fintech-Notes.pdf, (2017).

  10. King, R.J., Zavyalova, K., Josefsson, K.: Introducing the FOAM Protocol, https://blog.foam.space/introducing-the-foam-protocol-2598d2f71417, (2017).

  11. Liu, J., Li, H., Gao, Y., Yu, H., Jiang, D.: A geohash-based index for spatial data management in distributed memory. 2014 22nd International Conference on Geoinformatics. pp. 1–4 (2014).

1. https://www.sarttac.org/content/dam/imf/Spring-Annual%20Meetings/SM18/Fintech/FinTech%20Exchange%20at%20the%20iLab.pdf
2. https://www.itu.int/en/ITU-T/Workshops-and-Seminars/201711/Documents/3.%20S3_Lee.pdf