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Where does IPFS store it’s files?

February 28, 2017
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If you were wondering where IPFS, the Inter Planetary File System, aka global distributed and decentralised database stores its files, read on. The best place to start is to follow the ‘Getting Started’ page at: https://ipfs.io/docs/getting-started. You’ll have to install it first which is very quick. After you run ipfs init you will get a link to a readme file which looks like this: The question I had was where was this file being served from? I finally found out that it was in my local drive at $HOME/.ipfs/blocks/R3/CIQBED3K6YA5I3QQWLJOCHWXDRK5EXZQILBCKAPEDUJENZ5B5HJ5R3A.data To figure this out, all you have to do is run a grep like below: >> grep -rn "interfacing" * It seems obvious but as a complete newbie, even the simplest things can throw you off.
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IPFS basic intro videos

February 22, 2017
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If you are interested in understanding what IPFS is, these 2 videos are the quickest way to get a high level view. At about 20 minutes each the first one shows you how it works with actual examples which is great and the second one is a clip from Devcon2 in Shanghai where it gives a good insight into what it is and what it does from a non technical point of view. By non technical I mean there is no code involved but it’s still technical in terms of the words used.
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Don’t forget what self sovereign identity system uPort doesn’t claim to do

February 19, 2017
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Introduction uPort is a neat concept of self sovereign identity but there is one thing to keep in mind. uPort is a neat concept of self sovereign identity but there is one thing to keep in mind. It doesn’t remove the need for trust in 3rd parties but instead users choose the 3rd parties they want to trust. Firstly, lets do a quick recap on the basic concepts. Firstly, lets do a quick recap on the basic concepts Basic concepts Self sovereignty can be thought of as having self authority or for yourself to be in control of something. Self Sovereign Identity is the ability to own and control your identity. Another neat definition is: “Self-sovereign identity is a concept where the individual has ultimate control over their identity and is the final arbiter of who can access and use their data and personal information” – John Lilic ( ConsenSys). This is an interesting concept because have you ever stopped to think if you actually own your identity? Your name, your date of birth (D.O.B), or your work experience that you display on LinkedIn, who owns that? Your hobbies, the places you have visited, your martial status on Facebook, who owns that? […]
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Microsoft Virtual Academy Blockchain As A Service Course

February 13, 2017
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Microsoft Virtual Academy (MVA) has recently published a Blockchain as a Service (BaaS) training course which is worth a look. It talks about Ethereum, solidity, smart contracts and the devops process for blockchain development. It naturally has a Microsoft Azure bias which is helpful in understanding what Microsoft offers The presentation format and MVA portal is very similar to that of the Princeton University course with transcripts, forums, a progress bar and course information and covers 5 modules. Distributed Ledgers 101 – 48 mins (3 videos) Smart Contracts Explained – 40 mins (3 videos) Decentralized Applications and Architecture – 35 mins (3 videos) DevOps for Blockchains on Azure 5 – 46 mins (3 videos) Development of Decentralized Applications – 44 mins (4 videos) The presenters were Cale Teeter and Derek Martin. Links to the course: https://mva.microsoft.com/en-US/training-courses/microsoft-blockchain-as-a-service-17104 https://mva.microsoft.com/ (keyword search: Blockchain) What was good about the course? The course was well organised and structured. The demo at the end of each course was helpful in terms of seeing what could be done in Microsoft Azure. Module 4 on devops was good providing insight into some of the considerations required. Module 5 showing the development ecosystem was excellent. My new word of the […]
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Neat site for monitoring active crowd sales of coins

January 30, 2017
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An interesting site that lists past, current and upcoming ICO (Initial Coin Offering). https://cyber.fund/radar
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Does notarization on the blockchain actually work?

January 25, 2017
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Introduction At first glance it may seem that blockchain technologies can revamp or disrupt notary services. There certainly has been a lot of hype and articles in this area. To understand whether or not this is true we need to look at what notary services provide, what blockchain technology provides and see if one can replace the other. Notary services Notaries provide a wide range of services. The ones relevant to us are: Witness and certify the validity of signatures on documents. Certify the authenticity of the documents themselves. Documents on the blockchain Storing information on the blockchain provides proof of: Timestamp: A digital fingerprint of the document on the blockchain proves that the document, containing an idea for example, was created at that point in time. Data on the blockchain, in geek speak is immutable. That means it cannot change. It is locked within the blockchain forever. Ownership: With public/private key technology you can prove that you were the person that put the document there. Independently verifiable: Once it is there, any 3rd party can verify that the documents were placed there by the person who holds the private key. The blockchain is also secure, global and decentralised. How does […]
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Mobile is Eating the World by Benedict Evans

January 22, 2017
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An insightful presentation on the progression of technology highlighting how mobile is becoming nothing special anymore and the rise of machine learning and autonomous systems. Blockchain concepts such as trustlessness and decentralisation were yet to feature but one can imagine it’s not too far away.
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An epic list of bitcoin research

January 17, 2017
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Here is a link to an epic list of bitcoin research. It makes a great reading list. Here is an exported list in case the Google link above breaks. Bitcoin Academic Research  
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The Death of Money – Andreas Antonopoulos

January 16, 2017
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A great interview with Andreas once again explaining things very clearly. The interview starts at 6:20 and is a recommended watch. Part 1 is on YouTube. You will have to sign up to London Real to watch the entire clip. It is entirely worth it!  
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Why Understanding P2PKH is Important in Blockchain

January 13, 2017
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Introduction P2PKH is an important acronym to learn. It stands for “Pay To Public Key Hash” and is the most common form of transaction on the bitcoin blockchain. Part 1: What on Earth does “Pay to Public Key Hash” mean? In a bitcoin transaction, the “Public Key Hash” is synonymous to a “bitcoin address”. (A bitcoin address is derived from a the hash of your public key for the technically minded). So let’s reword P2PKH to mean “Pay to this bitcoin address”. That’s not so scary is it? P2PKH is therefore an instruction on the blockchain to transfer ownership from the current owner to the new owner of the bitcoin address. Why this is important to understand? This instruction can be modified for example to say, “pay to this bitcoin address OR that bitcoin address”. This is basically a smart contract in its simplest form. It is also known as multi-sig. A multiple signature condition that states “please provide any 1 of the 2 provided bitcoin addresses for this transaction to evaluate to true and execute”. That is the basics of P2PKH. Part 2 tackles this from a technical angle. Part 2: What does it “technically” really mean? There are […]
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Good overview of some technical blockchain concepts

January 12, 2017
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This is a good resource for some really technical information on bitcoin and blockchain fundamentals. You know you’re getting heavy when you see the word endian! The information was well laid out over several  sections and the concepts built upon each subsequent section. The audience expectations were laid out which was a nice touch. I would have included the section number in the title so I knew how far in I was and how many more sections there were. The term “outpoint” was introduced in section 9 and I first thought it was a typo for output but Davide confirmed it wasn’t. It would have be good if it was explained in a bit more detail. The example code was one of the highlights. A lot of people talk about stuff, but it’s the implementation or the “how” part that is the hardest. The last section on wallets was interesting as well. This would be a good area to possibly expand on.  
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OpenSSL Cookbook

January 11, 2017
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Blockchain technology relies heavily on understanding public and private keys. How they are generated and used. This OpenSSL Cookbook is a good reference. I found the first half more informative and useful than the second half. Here is the link to the online version: https://www.feistyduck.com/library/openssl%2dcookbook/online/ For other formats, check out: https://www.feistyduck.com/library/openssl-cookbook/
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Learning The Lightning Networks

January 10, 2017
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There are lots of resources to read when learning about the Lightning Network for blockchain transactions. Here is a recommended list of resources in a specific order. Lightning Network Summary from https://lightning.network is a great one pager that is very clearly written and provides a great summary intro. https://www.youtube.com/watch?v=8zVzw912wPo “The Scaling Bitcoin to Billions of Transactions Per Day” also on the lightning.network home page is important as well. It is clear with good examples. This 3 part article does a good job also. https://bitcoinmagazine.com/articles/understanding-the-lightning-network-part-building-a-bidirectional-payment-channel-1464710791 https://bitcoinmagazine.com/articles/understanding-the-lightning-network-part-creating-the-network-1465326903 https://bitcoinmagazine.com/articles/understanding-the-lightning-network-part-completing-the-puzzle-and-closing-the-channel-1466178980 Finally, some discussions at bitcoin.stackexchange will come from a different angle also. http://bitcoin.stackexchange.com/questions/43700/how-does-the-lightning-network-work-in-simple-terms http://bitcoin.stackexchange.com/questions/42639/what-are-the-trade-offs-between-transacting-on-lightning-network-and-bitcoin-mai These are your starters. If you want to get more technical, the whitepaper from the https://lightning.network homepage is your next step. It’s 59 pages and the first 10 or so pages are ok, but it then jumps another gear. Unfortunately what put me off was the abstract. The bitcoin protocol can encompass the global financial transaction volume in all electronic payment systems today, without a single custodial third party holding funds or requiring participants to have anything more than a computer using a broadband connection. A decentralized system is proposed whereby transactions are sent over a network of micropayment channels (a.k.a. payment channels or […]
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A very high quality Bitcoin Blockchain Online Course

December 31, 2016
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Introduction If you are serious about cryptocurrencies and blockchain technologies, this is the course you want to take. To borrow a line out of “The Chase UK”, it’s a course “right out of the top drawer“. Don’t let the course title “Bitcoin and Cryptocurrency Technologies” mislead you. It’s all about “blockchain” technologies. With the “blockchain” rave rampant, this course highlights blockchain technologies specifically with bitcoins as the example application. Content I missed the first intake for this course about a year ago but managed to enrol this time around. It’s presented as an 11 week course and with lectures via videos. Summary of course. See full details here: Week 1: 6 videos, 55 min: Introduction to Crypto and Cryptocurrencies Week 2: 5 videos, 71 min: How Bitcoin Achieves Decentralization Week 3: 6 videos, 74 min: Mechanics of Bitcoin Week 4: 7 videos, 78 min: How to Store and Use Bitcoins Week 5: 5 videos, : 84 min: Bitcoin Mining Week 6: 6 videos, 109 min: Bitcoin and Anonymity Week 7: 8 videos, 69 min: Community, Politics, and Regulation Week 8: 5 videos, 42 min: Alternative Mining Puzzles Week 9: 5 videos, 83 min: Bitcoin as a Platform Week 10: 4 videos, 62 min: Altcoins and the Cryptocurrency Ecosystem Week 11: 4 videos, 82 min: The […]
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OP_RETURN 40 to 80 bytes

December 30, 2016
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At first it is really confusing understanding the actual size of the OP_RETURN field. This field in a bitcoin transaction allows arbitrary data to be written to the bitcoin blockchain and was “standardised” in v0.9.0 of the bitcoin core client on 19 March 2014. The core developers noted however that “Storing arbitrary data in the blockchain is still a bad idea; it is less costly and far more efficient to store non-currency data elsewhere. 5 Jun 2013 was the initial pull request for the 80 byte OP_RETURN https://github.com/bitcoin/bitcoin/pull/2738 These notes go with it: http://bitcoinfoundation.org/core-development-update-5/ On 25 Feb 2014, it was proposed to be reduced to 40 bytes as can be seen by this pull request https://github.com/bitcoin/bitcoin/pull/3737. The comments make an interesting read! It was then accepted (merged) into the code on 27 Feb 2014 as part of v0.9.0. On 16 Nov 2014 there was a pull request to have the OP_RETURN size increased “back” to 80 bytes. https://github.com/bitcoin/bitcoin/pull/5286 “The maximum size for OP_RETURN outputs used to be 80 bytes, then got changed to 40 bytes to be on the safe side. We have now been running with 40 bytes for about 9 months, and nothing catastrophic happened to the Blockchain, so I am proposing to increase […]
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Segregated Witness Explained Like I’m 5

December 21, 2016
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Introduction Segregate Witness is a neat concept invented by Pieter Wuille. Pieter has a Ph.D in computer science and is part of the bitcoin core development team since 2011. What is SegWit? The short non technical version Segregated Witness, or SegWit as it is commonly known is where data, or more specifically data related to signatures are removed from bitcoin transactions making them smaller in size. This in turn makes the blocks smaller meaning more transactions can be included in a block. The short technical version “Segregated witness (segwit) is a soft fork that, if activated, will allow transaction-producing software to separate (segregate) transaction signatures (witnesses) from the part of the data in a transaction that is covered by the txid.” The long version Background SegWit was officially released on October 2016 in v0.13.1 of the bitcoin core code. It’s the result of about 1 years work and was presented at the Bitcoin Scaling Conference in Hong Kong in December 6th 2015. The details To fully understand SegWit, it is important to understand the make up of a block and a transaction. Inside a transaction are scriptSig and scriptPubKey fields. This is where signature data is contained. Pieter asks the […]
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POS: Prove Your Steak on the Blockchain

October 28, 2016
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Introduction The first thing that came to mind when I saw “PoS” was Point of Sale. EFTPOS is very popular in New Zealand and Australia but this has nothing to do with collecting payment. It also has nothing to do with proving how much steak you can eat. That would be interesting though! PoS stands for Proof of Stake and is one way to achieve consensus on the blockchain. Other ways to achieve consensus on the blockchain include (but not limited to): Proof of Work Proof of Activity Proof of Capacity Proof of Storage Proof of Work (PoW) is currently the most common and is being used on the bitcoin blockchain. To understand more about PoW read this. Proof of Stake (PoS) has made some noise in recent times in particular with Ethereum looking at moving away from PoW to PoS. Before we look at PoS, first let’s see why we need it. Consensus In a distributed, trustless computing network, there needs to be a way for a collection of machines to come to an agreement of facts. In a blockchain, any participating node on the network can create a candidate block very easily by obtaining the relevant software and verifying the transactions […]
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Neat paper on Blockchains, Smart Contracts and IoT

October 2, 2016
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Here is a link to a neat paper called Blockchains and Smart Contracts for the Internet of Things by Konstantinos Christidis, (Graduate Student Member, IEEE) and Michael Devetsikiotis, (Fellow, IEEE). http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7467408 It does a great job explaining some of the basics of blockchains and smart contracts before getting into lots of possible applications. If the above link is broken, here is another link: blockchains-and-smart-contracts-for-the-iot
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IBM Blockchain for developers

September 15, 2016
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Introduction I had heard about IBM donating 44k lines of code to the Hyperledger project a while ago and was curious interested to see what IBM had to offer in the blockchain space. IBM has a neat little learning path to understand more about blockchain technologies. It’s a free self paced course that takes a few hours (not really the 6 that it says) and does a pretty good job at explaining IBM, blockchain and the Hyperledger. What was good The course was professionally done with goals, quizzes at the end of each course, videos and notes and the best part was the hands on development environment Bluemix. It’s only a 30 day trial but no credit card was required. The content was good where IBM introduced terminology such as “world state” to mean the state of the blockchain or the ledger and “blockchain fabric” to mean blockchain framework. Above is a neat diagram of the various blockchain components in the IBM Hyperledger stack. The above screenshot shows the 1 click blockchain deployment process within Bluemix where everything is set up automatically. The car leasing demo was interesting behind the scenes but the front end interface was just like any […]
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Learning how to secure the blockchain

September 4, 2016
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It has been a very busy few weeks since my first trip to the US. As part of my STEM contribution, I was looking for old mining boards to first learn how mining works and then to share this knowledge with the younger generation. I put a shout on the community forums a while ago and a very generous person offered one of his boards. It would have cost a lot to send it to NZ so I ended up picking it up while in the US. From attending various meet ups and talking with all sorts of people, everyone wants “in” on blockchain applications and smart contracts. That is because it’s the buzz at the moment. The good old bitcoin cryptocurrency has been left in the dust. There is also the negative connotation that surrounds bitcoins such as “it’s used for buying drugs” and “it’s a speculative currency”. Whilst these maybe true, understanding components of how bitcoin works provides an excellent foundation to build upon. One example is analysing what is inside a blockchain. Another example is that of securing the blockchain, aka mining. Currently the main algorithm used to secure transactions on the blockchain is Proof of Work. It has […]
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