On the 3rd of January 2009 a person by the name of Satoshi Nakamoto, brought Bitcoin to the world, making the term blockchain a household name. The concept behind blockchain actually dates back a lot further than most people realize.
In 1991, Stuart Haber and W Scott Stornetta released their research paper – ‘How to timestamp a digital document’. The premise of the research paper, made reference that with the growing rise of text, audio and video documents in a digital format that such documents can or could be easily modified or forged.
They concluded that what was needed was the time stamping of the data not the medium. Reference was made to methods of certification, secure digital time stamping.
They concluded that this has to satisfy two criteria namely,
1. Secure digital time stamping of the actual bits of the document, making no assumptions about the physical medium on which the document is recorded.
2. The date and time of the time stamp must not be forgeable.
In order to satisfy the criteria, they discussed the application of a family of cryptographically secure collision free hash functions – This we will look at in more detail in the next blog post – ‘Understanding SHA (Secure Hash Algorithm) 256.
• They made mention then of the practical applications for such a secure digital time stamping – To establish precedence of intellectual property without disclosing its contents
• Looking at the importance of where the date is not as significant as simply whether the document has been tampered with. – So long after the document has been created, there then lies the motivation to tamper with the document.
Therefore one can conclude that the basic constructs of the blockchain are based on this methodology.
As a simple definition, a blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Obviously there is a lot more to a blockchain. So what constitutes a blockchain?
• Data – This can be any form of data.
• Hash – This is simply like a digital fingerprint of some data , with each hash being unique
• Previous Hash – The hash adopted from the previous block. The first block, or genesis block will not have a previous hash, as it’s the first block. Block two will have block one’s hash and is cryptographically linked to block one via this hash.
These blocks can be viewed as a sort of ‘current ‘part of the blockchain, which records some, or all of the current transactions. Once completed, a block goes into the blockchain as a permanent database. These blocks are then connected to each other like links in a chain.
By storing blocks of information that are identical across its network the blockchain cannot be controlled be any single entity and has no single point of failure.
In essence blockchains help to guarantee the validity of a transaction, by recording it not only on a main register but a connected distributed system of registers – These are all connected through a secure validation system.
So with Bitcoin being our reference, a global network of computers uses blockchain technology to jointly manage the databases that records bitcoin transactions, so it’s the network that manages Bitcoin, not any one central authority.
In the next blog , I will be looking into more detail on how the blocks are cryptographically linked via the Secure Hash Algorithm .