The blockchain concept came into the picture in 2011. However, it is not fully true. This concept was there earlier in one or another form, and it evolved gradually and became famous when this concept was used to design cryptocurrencies like Bitcoin.
The first use of this concept of a cryptographically secured chain of blocks came in 1991 in a paper by Harber and Stornetta. They developed and presented a mechanism for time-stamping digital documents. A digital document is created and modified by multiple people, and entire details are captured and stored in the chain of blocks.
The goal was to maintain a list of timestamps when the document has been first created, followed by when the document was edited in a subsequent but secure way such that no one will be able to make a change in the timestamp value.
The timestamp is important for the document management purpose because many of the time, we want to see when the document was last edited or if some person claim that he/she has not made any edition in the document, it can easily verify whether that person has actually edited the document or not.
To solve this particular problem, Harber and Stornetta have used this concept of a chain of blocks. However, they have not claimed this as a Blockchain, but the concept is similar to Blockchain.
Let us understand the same with an example:
- A sequence of timestamps such as TS1, TS2, TS3, TS4, and so on are denoting when the document is created or edited.
- Whenever a client accesses a document, it constructs a block consisting of a Sequence Number, Client ID, Current Timestamp, and a previous block hash value.
- After modification, it takes the above parameters, generates a new block, and appends with the documents.
The advantage of this hash chain is that if we want to make some change in the timestamp value. For example, if we want to change the timestamp value TS1, we need to update all the hash values starting from H2, H3, and H4 all the subsequent hash values, and people will able to observe that all these values have been changes. This way, they will be able to detect that someone is trying to tamper with the document.
This way, the concept of chain of blocks by connecting them by the hash function, that was used to cryptographically securing the timestamp value of a digital document, so this particular architecture looks like something similar to Blockchain where we have multiple blocks of data, and a hash value connects these blocks of data.
References:
- NPTEL lecture series on Blockchains Architecture, Design and Use Cases by Prof. Sandip Chakraborty, IIT Kharagpur.
- https://en.wikipedia.org/wiki/Cryptographic_hash_function
- https://link.springer.com/content/pdf/10.1007/BF00196791.pdf
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