Throughput targets and Tachyon’s role
The reason for building all this is arithmetic.
Mastercard and Visa process more than 50,000 transactions per second, and the team calls that figure ‘“its floor, not its target.” Zcash’s current cryptography would require a node to take in and verify more than 500 megabytes of data every second to keep up, because every private transaction carries a proof, and proofs are large.
That is roughly a full DVD of data arriving every ten seconds, continuously, and no current Zcash software runs anywhere near that. But the missing piece is the reason each bottleneck exists.
Bowe’s Project Tachyon is tackling this by working on recursive proofs, in which one proof attests to the validity of thousands of others, dramatically reducing the amount of data that must be checked at consensus.
Under Tachyon, a node verifies a single proof instead of the thousands, which the team says reduces the requirement for consensus data from 100 megabytes per second to 500 megabytes, a level they claim is technically achievable with careful engineering.
Wallet bottlenecks and Valar’s PIR solution
Wallets have a different problem. Because Zcash hides who a transaction is for, a wallet cannot ask a server which transactions belong to it without giving itself away. It pulls down everything and tests each one, which is why wallet software tops out at about one transaction per second.