How to use blockchain to power a timestamping service

Blockchain, the technology behind the digital currency Bitcoin, is believed to soon power a very wide range of different applications. “I have researched, implement, tested and delivered a fully functioning proof-of-concept product to use blockchain to run a simple timestamping service,” says Mohammad Alhaj Ali, a student of Uppsala University, Sweden, who has done his master’s thesis at identity and security company Nexus Group.

Step one was to investigate what derivative of the blockchain technology is best suited to power the timestamping service, according to Alhaj Ali.

“A blockchain is a distributed database that runs on ten thousands of computers simultaneously. The blockchain maintains a continuously growing list of ordered records, called blocks, and they are read-only by design. But there are some different flavors of the blockchain technology,” says Alhaj Ali.

Timestamping is used to be able to prove that a certain file or digital document existed at a certain time. The files and documents can be anything from digital identities to digitized medical records.

“I have made a website where users can log in and upload files that they want timestamped. After a file is uploaded, the timestamping service automatically calculates the hash value of the file,” says Alhaj Ali.

The hash value is computed with a cryptographic algorithm and the result is what can be described as a digital fingerprint of the file’s contents. The hash value can be used to uniquely identify the file and prove that the file has not been tampered with after the hash value was calculated.

“If the user does not want to upload the file to the web site because of privacy concerns, they can calculate the hash value locally and then upload the hash value instead of the file. No matter which method is chosen, the next step is for the user to click ‘timestamp.’ Then the backend system, which is a blockchain, gets the request,” says Alhaj Ali.

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The blockchain processes the request, and if 51 percent of more of the computers running the blockchain accept the request, the hash value is registered, together with the user’s identity and the time.

“The list with the registered information is public and searchable. If you want to verify that a document belongs to me and was timestamped at a certain time, you can search for the file’s hash value or the time and date, and the system shows you the public information,” says Alhaj Ali.

There are several benefits with a blockchain powered timestamping service compared to a traditional service, according to Alhaj Ali.

“A traditional timestamping service, that is run on a single computer, requires installation and maintenance, which costs more to use than a distributed system. A single computer is also more vulnerable and at risk for attacks compared to tens of thousands of connected computers. The fact that the blockchain code is open and accessible to everyone makes the system transparent, which further increases user trust. And since a blockchain is read-only by design, it is impossible to manipulate the data,” says Alhaj Ali.

Kim Freskgård, head of software development at Nexus, agrees that blockchain offers increased security and trustworthiness.

“When using blockchain, we know that we can rely on the data. And the system will always be up and running, no matter what happens,” says Freskgård.