Town Crier Service Delivers Solid Data To Coders
Ethereum's EDCCs may be receiving a boon in the form of Town Crier (TC), a tool designed to provide trustworthy information for use by contracts.
Project leader Fan Zhang provided insight to ETHNews about how TC functions:
"TC has a smart contract frontend on Ethereum chain, which accepts access requests from user contracts and delivers the data feed furnished by the TC server to the requesting contracts. So the way an application contract could use TC is simply to send requests to the TC contract and provide a callback address, which will be called with the packaged data feed."
If given bad or corrupted information, an EDCC can be considered untrustworthy, so TC uses a layer of cryptography to verify that data is not altered from its original state before providing it to coders.
"What TC offers is data feeds with strong authenticity guarantee, meaning TC can guarantee that the source of the data feeds is indeed from credible information sources," said Zhang.
Another capability TC introduces is the option to hide data within an EDCC so that only parties to the contract are able to see it. Such innovations step away from the open source transaction data that is currently viewable on the Ethereum blockchain. Zhang explained leveraging the confidentiality provided by hardware, such as Intel SGX, by which user data "is encrypted under a public key whose corresponding secret key is only known to the trusted hardware."
"More precisely, trusted hardware can generate a pair of keys and keep the secret key concealed. That way, no one (no even the operators of TC) except for the trusted hardware can see the secret key. Therefore users' requests are kept secret from anyone."
Ethereum founder, Vitalik Buterin told MIT Technology Review his take on TC. “The lack of data feeds from the outside world is definitely a large impediment, and Town Crier could go far in mitigating this issue,” he said.
With a paper first released in February 2016, and further collaboration at the IC3-Ethereum Crypto Boot Camp in July that same year, TC will be ready to demonstrate the project on May 15, 2017. The demo will show how TC can offer data feeds that include stock prices, weather reports, flight information, virtual currency exchange rates, and UPS package tracking. Ari Juels, professor at Jacobs Technion-Cornell Institute, will be releasing the software as open source for developer applications.