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323 Stack Exchange (2013) What Happens if Your Bitcoin Client Generates An Address Identical to Another Person's?,
available at https:// bit .ly/ 2TyI2ox; Discussion of key duplication and collisions at Reddit at http:// bit .ly/ 2LsTDFG; See
also number of unique addresses used in the Bitcoin blockchain at http:// bit .ly/ 2LtMNj7
324 Stablecoin definition.
325 Cointelegraph (2019) Oxfam Trials Aid Distribution With DAI, Future Use 'Highly Likely', available at http:// bit .ly/
2Y4o2w0
326 The further back in the chain a block is, the more likely it is finalized and unlikely to be superseded by a longer chain.
Six or seven confirmations may be safe.
327 See Grigorean, A (2018) Latency and finality in different crypto-currencies, https:// bit .ly/ 2VYNEts
328 Mosakheil, J (2018) Security Threats Classification, available at http:// bit .ly/ 2XPJXf8
329 In addition, the merchant should consider connecting to a sufficiently large number of random nodes on the network
to limit the chances of not seeing a double spend transaction. See Bamert, T & Decker, C et al. (2013) Have a Snack, Pay
with Bitcoins, available at https:// bit .ly/ 2WbT3h1
330 Karame, G & Androulaki, E (2012) Two Bitcoins at the Price of One? Double-Spending Attacks on
330 Fast Payments in Bitcoin, available at http:// bit .ly/ 2xWalEI; See also Podolanko, J & Ming, J et al. (2017) Countering
Double -Spend Attacks on Bitcoin Fast-Pay Transactions, available at http:// bit .ly/ 32wX0AR
331 Karame, G & Androulki, E, et al. (2015) Forwarding Double-Spending Attempts in the Network, available at https:// bit .ly/
2FhKiMI
332 GAP600 (2019) GAP600 Platform, available at http:// bit .ly/ 2YaKTdm
333 For a list of SC security tools. See Consensys (2019) Security Tools, available at http:// bit .ly/ 2JRJmzr
334 Several other programming languages can be used and will compile for Ethereum as well. See Nicolic (2018) Finding
the Greedy, Prodigal and Suicidal Contracts at Scale, available at http:// bit .ly/ 30A2XLk; Li,X (2018) A Survey on the
Blockchain Systems, available at http:// bit .ly/ 2GkRLui ; Tsao, P (2018) Blockchain 2.0 and Ethereum [Blockchain Basics
Part 3], available at http:// bit .ly/ 2SuoIcQ
335 Since the majority of DLT activity on smart contracts relates to Ethereum, this section will primarily focus on Ethereum-
specific challenges and vulnerabilities, many of which can provide insight into the difficulties which may be inherent in
the introduction of the smart contract concept.

336 Bitcoin script is not Turing Complete. Bitcore (2019) Script, https:// bitcore .io/ api/ lib/ script; Solidity is Turing Complete,
available at http:// bit .ly/ 2XPxMPq; Singh, N (2019) Turing Completeness and the Ethereum Blockchain, available at
http:// bit .ly/ 2M0rFAI
337 http:// bit .ly/ 2JGb4k7; Solidity, a language similar to Javascript, is the most predominant in usage and robust, although
others exist such as Serpent, LLL and Viper. Dika (2017) and others.
338 While bytecode is in compiled form, it is capable of being decompiled back into source code. Pillmore, E (2019) The
EVM Is Fundamentally Unsafe, available at http:// bit .ly/ 2O46wYI
339 The Ethereum platform features two types of accounts – a regular ‘Externally Owned Account’ which is the user
address which stores the user’s Ether - Ethereum’s native currency; and (2) a ‘Contracts Account’ address which
identifies a newly created contract and consists of (i) a storage area for Ether; and (ii) the contract code which is stored
in compiled EVM bytecode language which is typically the product of using high level programming languages such
as Solidity. Rush, T (2016) Smart Contracts are Immutable — That’s Amazing…and It Sucks, available at http:// bit .ly/
32wxfAB

340 The code was written by Slock.it. For an explanation of the project, see http:// bit .ly/ 2xXviio
341 Leising, M (2017) The Ether Thief, available at https:// bloom .bg/ 2SneOcW
342 Buterin, V (2016) Hard Fork Completed, available at http:// bit .ly/ 32CmGfi
343 Kahatwani, S (2018) Ethereum Classic (ETC): Everything Beginners Need To Know, available at http:// bit .ly/ 2M7gvKa;
Falkon, S (2017) The Story of the DAO — Its History and Consequences, available at http:// bit .ly/ 2Z14E4a
344 See in relation to issues discovered with the Ethereum blockchain; Buterin, V (2016) Thinking About Smart Contract
Security, available at https:// goo .gl/ iH78GN; and Daian, P (2016) Chasing the DAO Attacker’s Wake, available at https://
goo .gl/ DxgOHD.
345 See Cornell Sun (2016) Cornell Prof Uncovers Bugs in Smart Contract System, Urges More Safety in Program Design,
available at https:// goo .gl/ d6d4F2.

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