The first time I heard about blockchains was at a party where a friend of mine spent the night talking my ear off about this thing called Bitcoin and why I should buy some. I suspect many others have had a similar experience. While Bitcoin can be credited with introducing blockchains — a type of distributed digital ledger — into popular discourse, it was not the precursor to the obscure technology’s key features.
In fact, the world’s oldest blockchain is 13 years older than Bitcoin and it’s been hiding in plain sight, printed weekly in the classified section of one of the world’s most widely circulated newspapers: The New York Times.
The world’s first blockchain
At its core, a blockchain is just a database maintained by a network of users and secured by cryptography. When new information is added to the database, it is divided into ‘blocks’, which can be thought of as containers for this data. Every so often a new block is created and linked to a “chain” of previously created blocks. Each block has a unique ID called a hash, which is created by running the ID of the block that preceded it and the data stored in the current block through a cryptographic algorithm. This ensures the integrity of all data stored on the blockchain, as changing the data in a block would produce a different hash.
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Today, “blockchain” is treated as shorthand for the technology that underpins most cryptocurrencies and digital token systems, such as Bitcoin or Ethereum. While blockchains can be used as an immutable record of financial transactions, this is far from their only use. In fact, any type of information can be added to a blockchain, and in the past everything from cannabis strains and virtual kittens to sushi and rare art was stored in a distributed ledger.
Blockchains, insofar as they form a chronological chain of hashed data, were first invented by cryptographers Stuart Haber and Scott Stornetta in 1991, and their use cases were a lot less ambitious. Instead, Haber and Stornetta envisioned the technology as a way to time-stamp digital records to verify their authenticity. As she described in a paper published in The Journal of Cryptologythe ability to certify when a document was created or last modified is critical to solving issues like intellectual property rights.
In Meatspace, there are several mundane ways to timestamp a document, such as sending the document to yourself in a sealed envelope or entering chronological lines in a notebook. In these cases, any evidence of tampering, such as opening the envelope or trying to put a page in the notebook, will be obvious. But when it comes to verifying the authenticity of a digital document, it is much more difficult to determine whether the document has been altered.
As Haber and Stornetta realized, timestamping a digital record would require solving two problems. First, the data itself should be timestamped “so that it is impossible to change even part of the document without the change being obvious.” Second, it should be impossible to change the timestamp itself.
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An obvious solution to this problem is to send the digital record to a timestamping service that keeps the document in a “digital vault” that meets both of the above criteria. The drawbacks of this approach are that the privacy of the person submitting the document is compromised and the document may be corrupted when it is sent or stored by the service.
The solution that Haber and Stornetta came up with instead was to run the document through a cryptographic hashing algorithm, which produces a unique ID for the document. If even a single bit in the document is changed and the hashing algorithm is run through again, the ID will be completely different. This idea was coupled with the related idea of digital signatures, which can be used to uniquely identify the signer. So instead of sending the entire document to a timestamping service, users could simply send the cryptographic hash value, which the service could sign to ensure it was received at a specific time and not corrupted – a kind of notarized act a document IRL.
But where The New York Times come into play? In cryptocurrencies, hashes are placed in a public ledger known as a blockchain, where anyone can see for themselves that the integrity of the data is intact. Haber and Stornetta realized that the land’s papers could serve a similar purpose.
What Haber and Stornetta described in their 1991 research paper is a prototypical version of the blockchains that power most cryptocurrencies today. When Satoshi Nakamoto first described Bitcoin in a 2008 white paper, three of the eight papers mentioned were written by Haber and Stornetta. When asked how he felt about being the inspiration for Bitcoin, Stornetta told the Wall Street Journal that it felt “pretty cool.”
But 14 years before Bitcoin was invented, Haber and Stornetta created their own timestamping service called Surety to put their plan into practice.
Surety’s flagship product is called “AbsoluteProof”, which acts as a cryptographically secure seal on digital documents. The basic mechanism is the same as described in the original paper by Haber and Stornetta. Customers use Surety’s AbsoluteProof software to create a hash of a digital document, which is then sent to Surety’s servers where it is timestamped to create a seal. This seal is a cryptographically secured unique identifier that is then sent back to the software program to be stored for the customer.
At the same time, a copy of that seal and any other seal made by Surety customers is sent to the AbsoluteProof “universal registry database”, which is a “hash chain” made up entirely of Surety customer seals. This creates an immutable record of all surety seals ever produced, making it impossible for the company or any malicious actor to alter a seal. But it leaves out an important part of the blockchain equation: trustworthiness. How can anyone trust Surety’s internal data to be legit?
Instead of posting customer hashes to a public digital ledger, Surety creates a unique hash value of all new seals added to the database each week and publishes this hash value in the New York Times. The hash is listed in a small advertisement in the Time classified section under the heading “Notices & Lost and Found” and has been published once a week since 1995.
According to the company, “this makes it impossible for anyone — including Surety — to timestamp or validate electronic records that weren’t exact copies of the original.” Or at least almost impossible.
As co-founder of Ethereum, Vitalik Buterin joked on TwitterIf someone wants to compromise Surety’s blockchain, they can “create fake newspapers with another chain of hashes and distribute them more widely.” Since the New York Times has an average daily circulation of about 570,000 copies, this would probably be the stunt of the century.
Both Haber and Stornetta left Surety more than a decade ago to return to research, but today they both work as cryptographers on other blockchain projects. While they never made it rich in the brave new world of cryptocurrencies they helped create, Haber and Stornetta are the only people in the cryptocurrency world who can claim to have brought a whole new meaning to “the paper document.”