these transactions are theoreti-
cally anonymous, they can be com-
bined with other data to track and
even identify users. Vitalik Buterin,
creator of Ethereum, the world’s
network, has described zk-SNARKs
as an “absolutely game-changing
For banks, this could be a way
to use blockchains in payment sys-
tems without sacrificing their clients’
privacy. Last year, JPMorgan Chase
added zk-SNARKs to its own block-
chain-based payment system.
For all their promise, though, zk-SNARKs are computation-heavy and
slow. They also require a so-called
“trusted setup,” creating a cryptographic key that could compromise
the whole system if it fell into the
wrong hands. But researchers are
looking at alternatives that deploy
zero-knowledge proofs more efficiently and don’t require such a key.
Computer scientists are perfecting a
cryptographic tool for proving something without
revealing the information underlying the proof.
WH Y IT MATTERS
If you need to disclose personal information
to get something done online, it will be eas-
ier to do so without risking your privacy or
exposing yourself to identity theft.
A tool developed for
blockchains makes it
possible to carry out
a digital transaction
without revealing any
more information than
True internet privacy could finally
become possible thanks to a new
tool that can—for instance—let you
prove you’re over 18 without revealing your date of birth, or prove you
have enough money in the bank for a
financial transaction without revealing your balance or other details.
That limits the risk of a privacy
breach or identity theft.
The tool is an emerging cryptographic protocol called a
zero-knowledge proof. Though
researchers have worked on it for
decades, interest has exploded in
the past year, thanks in part to the
growing obsession with cryptocurrencies, most of which aren’t private.
Much of the credit for a practical zero-knowledge proof goes
to Zcash, a digital currency that
launched in late 2016. Zcash’s
developers used a method called
a zk-SNARK (for “zero-knowledge
succinct non-interactive argument of
knowledge”) to give users the power
to transact anonymously.
That’s not normally possible in
Bitcoin and most other public blockchain systems, in which transactions are visible to everyone. Though