[Cryptography] Zerocash DAP implementation

Jan Carlsson jancarlsson at Safe-mail.net
Mon Jul 6 20:41:20 EDT 2015

Here is an implementation of the zero knowledge payment scheme
from "Zerocash: Decentralized Anonymous Payments from Bitcoin
(extended version)" (http://eprint.iacr.org/2014/349 ):


There are other Zerocash implementations, notably the official
one. To my knowledge, kapital is the first to be released in
any form.

I must emphasize this is not a crypto-currency. It is not the
Zerocash everyone is waiting for. It contains the zero
knowledge payment transaction only. It does not contain
solutions for: 1) minting; 2) ledger; 3) public parameter key
pairs. The first two have the well known proof of work and
blockchain solutions in Bitcoin. The last is a new trust
dimension introduced by zero knowledge proofs.

Kapital will not be useful for most people. It is too early.
There are other problems such as decentralized ("trustless")
keys on the critical path.

Though not useful, kapital may be interesting. The smoketest
demonstrates the Zerocash pour transaction and simple smart
contracts using zkSNARK proofs. You can play with it on your

One motivation for releasing kapital too early is to
influence the cultural discussion. The Zerocash DAP scheme is
at the heart of kapital. However, the design encapsulates
pouring and inverts control from the viewpoint of writing
smart contracts. This may be important in the future.

More information about the cryptography mailing list