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183 See https:// www .augur .net/ . A ‘prediction market protocol’ which enables reporting of external events by blockchain
participants and uses a validation-dispute protocol to help ascertain veracity.
184 See https:// www .augur .net. See also the Augur white paper. Peterson, J; Krug, J; Zoltu, M et al. (2018) Augur: a
Decentralized Oracle and Prediction Market Platform, available at http:// bit .ly/ 2XPzH6C
185 ‘ChainLink is blockchain middleware that allows smart contracts to access key off-chain resources like data feeds,
various web APIs, and traditional bank account payments…. The LINK Network is the first decentralized oracle network;
allowing anyone to securely provide smart contracts with access to key external data, off-chain payments and any
other API capabilities. Anyone who has a data feed, useful off-chain service such as local payments, or any other API,
can now provide them directly to smart contracts in exchange for LINK tokens.’ See http:// bit .ly/ 2JO4CGx and http://
bit .ly/ 2So0zEu
186 ‘The Town Crier (TC) system addresses this problem by using trusted hardware , namely the Intel SGX instruction
set, a new capability in certain Intel CPUs. TC obtains data from target websites specified in queries from application
contracts. TC uses SGX to achieve what we call its authenticity property. Assuming that you trust SGX, data delivered
by TC from a website to an application contract is guaranteed to be free from tampering.’ Town Crier (2019) What is
Town Crier?, available at http:// bit .ly/ 30ALRgg

187 https:// aeternity .com/
188 Derksen (2019) An Introduction to Aeternity’s State Channels, available at http:// bit .ly/ 30F4vDW
189 Aeternity (2018) Blockchain Oracles, available at http:// bit .ly/ 2NYOc3g
190 https:// rlay .com
191 Rlay (2018) Rlay: A Decentralized Information Network, available at http:// bit .ly/ 2M5KLVM; Hirn, M (2018) Introducing
Rlay, a Decentralized Protocol for Blockchain’s External Data Problem, available at http:// bit .ly/ 2JQQ2xI
192 https:// gnosis .pm; See also Gnosis (2017) Gnosis Whitepaper, available at http:// bit .ly/ 32CdQxU
193 http:// bit .ly/ 30Lf4W9
194 Includes partition & delay, Tampering, and BGP Hijacking.
195 Apostolaki, M; Zohar, A & Vanbever, L (2018) Hijacking Bitcoin: Routing Attacks on Crypto-currencies, available at
http:// bit .ly/ 2JNzjLN; Stewart, J (2014) BGP Hijacking for Cryptocurrency Profit, available at http:// bit .ly/ 2LYd8Fn
196 Stewart, J (2014) BGP Hijacking for Cryptocurrency Profit, available at http:// bit .ly/ 2LYd8Fn
197 Apostolaki, M; Zohar, A & Vanbever, L (2018) Hijacking Bitcoin: Routing Attacks on Crypto-currencies, available at
http:// bit .ly/ 2JNzjLN; Stewart, J (2014) BGP Hijacking for Cryptocurrency Profit, available at http:// bit .ly/ 2LYd8Fn
198 http:// www .manrs .org/
199 Bissias, G; Ozisik, A; Levine, B et al. (2014), Sybil Resistant Mixing for Bitcoin, available at http:// bit .ly/ 2xSQu9h
200 Garner, B (2018) What’s a Sybil Attack & How Do Blockchains Mitigate Them?, available at http:// bit .ly/ 2LvO09I
201 An attacker gains control over a sufficient number of IP addresses to monopolize all incoming and outgoing
connections and to the target.
202 Heilman, E; Kendler, A; Zohar, A et al. (2015), Eclipse Attacks on Bitcoin’s Peer-to-Peer Network, available at http:// bit
.ly/ 2O2QU89
203 ibid
204 ibid
205 Unlike physical currency which immediately changes possession to a receiving party and can be instantly confirmed
on sight, digital currency can be submitted multiple times and requires confirmation of the sender’s possession of the
digital currency – which may not be instantaneous – to finalize a transaction.
206 Transaction times vary, with Bitcoin averaging 8-10 minutes and Ethereum 15 seconds to add a new block. However,
confirmation times for transactions typically require the addition of several new blocks before finality can be
considered low risk.
207 Johnson, K (2017) Ripple & the Gates Foundation Team Up to Level the Economic Playing Field for the Poor, available at
http:// bit .ly/ 32uG1ix
208 Culubas (2011) Timejacking & Bitcoin, available at http:// bit .ly/ 30G4DmI

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