Attached Pen and Sticky-notes as Proof of work

196 Major Revisions of the Objects 7.3.2

Major revisions are much more complex as the object representation has been fully discarded by the experienced users. They argued that the presentation of the Blockchain ledger does not match its functions. They suggested that instead of using the concept of container schemata6 (Hampe & Grady, 2005; Lakoff, 1987), the Blockchain should be designed based on the link schemata7 (Hampe & Grady, 2005; Lakoff, 1987). Thus, each set of transaction block should be linked to the one before and the one after within the Blockchain ledger. Hence, the findings led to a major revision of the representation of Blockchain ledger from a translucent paper grid to the transparent cubes that are connected with keyrings. For each cube, 2 pieces of keyrings are stick at the front and back of the cube. The cubes are chained with one to another by using it's front and back of the keyrings (Figure 7.3 – C).

6

Container schemata – The boundaries to prevent what is outside from affecting the entity or entities inside the container (Lakoff, 1987)

7 _{Link schemata – It consists of two or more entities, connected physically or metaphorically, and the bond}

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Figure 7.4: Organised Presentation of BlocKit's Objects

Replacing the Static Objects with Smart Objects 7.3.3

The initial design of the object to represent a private key is sticky notes written with the alphanumeric and black envelope to hide the sticky notes. The problems with this representation are that the experienced users are not able to relate the envelope and sticky notes as those were not positioned together. Due to this, the experienced users faced some difficulties to articulate the relationship between the two objects. To address this issue, the researcher refined the object by replacing a smart object, named Sifteo to increase the visibility of objects connections (Wikipedia, n.d.). The Sifteo cubes were programmed by a programmer. The actual private key is displayed as 64 characters in the range 0-9 and A-F (Caetano, 2015)

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and for the Sifteo cubes, each of the cubes’ screen display 32 characters. This is to represent ways to protect the offline private key that commonly used for Bitcoin paper wallet. The paper wallet is not stored in any online devices. The owner of the wallet printed the private key on a piece of paper and stores it securely in a safe place. Then if they need to use the Bitcoin, they will activate the private key in the online device such as through a mobile wallet app.

Thus, for the new design of private key with Sifteo cubes, in order to use the private key, the users have to combine both cubes by arranging the cubes next to each other. Once they connect the two cubes, the alphanumeric on both screens is hidden. This is to represent the analogy for the private key as it is protected and cannot be revealed. In order to give a sign to users that both cubes are related, is the cubes are programmed as if one of the cube is lifted up, then the other cube will lighten up. In addition, the representation of the private key has been extended by adding the sticky notes and pen to resemble the signature action by the owner of the private key (Figure 7.3 – B).

Structuring the Arrangements of the Object 7.3.4

The arrangements for the presentation of all objects in BlocKit are also more organised and structured. All the related objects representing one entity such as the pen and paper to represent proof-of-work, are grouped into one place. Each group of objects are numbered from 1-12 to ensure that the participants will be able to see all the 12 objects of BlocKit (Figure 7.4).

The New Object for the Newly Identified Blockchain’s Main Entity 7.3.5

The experienced users also had identified memory pool as an important Blockchain entity that needs to be materialised in BlocKit. Memory pool

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temporarily holds all the verified broadcasted Bitcoin transactions while waiting to be selected by the miners to group in a block for the confirmation works. Hence, this describes the memory pool as part-whole image schemata (Hurtienne, 2009; Hurtienne & Israel, 2007) as the miners can either select all of the transactions in the memory pool or just part of it. The properties of the memory pool are described as transparent, durable, portability, verifiable and safe. Thus, as suggested by the experienced users, a transparent and uncovered container is chosen as the new object of BlocKit to represent memory pool (Figure 7.3 – C).

Chapter Summary 7.4

This chapter reports the findings on the evaluation of BlocKit. Study 3 reflects the capability of BlocKit to provide the vocabularies to communicate as well as giving the impact on conforming, strengthening, and challenging experienced users’ mental models of Blockchain’s infrastructure. They also use BlocKit as a design tool to explore the principles and the requirements to design for trust in peer-to-peer Bitcoin transactions Bitcoin. Other than that, the outcomes of the workshop also suggest the revisions on BlocKit objects to support a clear representation of Blockchain’s entities. On the other hand, based on the experienced users’ suggestions for the principles and requirements to design for trust in Bitcoin users, a set of algorithmwas developed and validated, which will be discussed further in Chapter 8.

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Chapter 8

8

Design and Validation on Algorithms for

Trust in Peer-to-peer Bitcoin Transactions

on Blockchain

Figure 8.1: Chapter 8 of Thesis Structure Chapter 1 Introduction Chapter 2 Literature Review History of Money Trust in HCI Mental Model in HCI Bitcoin Cryptocurrency Blockchain Technology Chapter 4 The Trust Challenges and Opportunities among Bitcoin’s Users Chapter 5 The Trust Challenges and Opportunities among Bitcoin’s Miners Problem Identifications Chapter 6 Constructing BlocKit

Designing the Proposed Solutions Chapter 8 Design and Validation on Algorithms for Trust in Peer-to- Peer Bitcoin Transactions on Blockchain Chapter 9

Design for Trust in BitXFps Mobile Wallet Application

and Its Interface

Chapter 7

Evaluating BlocKit

Methods to Explore Opportunities to Mitigate the Challenges

Evaluating the Designed Solutions

Chapter 10

Evaluation of BitXFps Mobile Wallet Application

and How Its Interface Supports Trust Chapter 3 Methodology Chapter 11 Discussion Chapter 12 Conclusion Results