Frequently Asked Questions

The Zcash Foundation is currently focusing its efforts on two key programs: Zebra and FROST.

Zebra is the Zcash Foundation’s independent, consensus-compatible implementation of a Zcash node, written in memory safe Rust language. It can be used to join the Zcash peer-to-peer network which contributes to the resilience of the Zcash network by validating and broadcasting transactions and maintaining the Zcash blockchain state, in a distributed manner. 

• How is zebrad different from zcashd ?

The original Zcash node is named zcashd and is developed by the Electric Coin Company as a fork of the original Bitcoin node. Zebra, on the other hand, is an independent Zcash node implementation developed from scratch. Since they implement the same protocol, zcashd and Zebra nodes can communicate with each other and maintain the Zcash network interoperably.

• What are the benefits of running zebrad?   Better performance: since it was implemented from scratch in an async, parallelized way, Zebra is currently faster than zcashd.

1. Better security: since it is developed in a memory-safe language (Rust), Zebra is less likely to be affected by memory-safety and correctness security bugs that could compromise the environment where it is run.
2. Better governance: with a new node deployment, there will be more developers who can implement different features for the Zcash network.
3. Dev accessibility: supports more developers, which gives new developers options for contributing to Zcash protocol development.
4. Runtime safety: with an independent implementation, the detection of consensus bugs can happen quicker, reducing the risk of consensus splits.
5. Spec safety: with several node implementations, it is much easier to notice bugs and ambiguity in protocol specification.
6. User options: different nodes present different features and tradeoffs for users to decide on their preferred options.
7. Additional contexts: wider target deployments for people to use a consensus node in more contexts e.g. mobile, wasm, etc.

• When will zebrad be able to fully participate in the Zcash network?

It is anticipated that Zebra will be able to fully participate in the Zcash network upon the activation of NU5 Mainnet, in the beginning of 2022. 

• How can I install and run zebrad?

zebrad is still under development, so there is no supported packaging or install mechanism. To install and run zebrad, follow the following instructions.

• Where can I find the user and developer documentation for Zebra? 

• • This section contains details on how to install, run, and instrument Zebra.
  • This section contains the contribution guide and design documentation for Zebra.

FROST is a Flexible Round-Optimized Schnorr Threshold signature scheme designed to reduce the interaction between participants who jointly own a private signing key and wish to use this private key to sign a message (in the case of Zcash, FROST will be used to sign transactions from joint owners of a signing key). 

FROST is a collaboration between the Zcash Foundation and the University of Waterloo.

• What was our motivation in designing FROST?

The motivation to design FROST was simple. Because the mission of the Zcash Foundation is to build and deploy privacy-enhancing technologies for the public good, we work to ensure that using Zcash is as private and secure as possible. As part of this goal, Zcash transactions should be publicly indistinguishable- i.e, an adversary observing the blockchain should not be able to gain any information about who the payment is for, how much the payment is, or who authorized the payment.

While the above goals are achieved in Zcash in a single-party setting due to the use of ZK-SNARKS, Zcash previously did not have a good mechanism to achieve this goal in a multi-party setting, where a group of users want to jointly control funds and authorize transactions. 

Prior to FROST, the best protocols to perform this signing process required either undesirable implementation complexity, high network overheads to perform signing operations, the inability to support a threshold number of signers, or undesirable privacy leaks such as exposing the number of signers.

Consequently, our decision to design a new threshold scheme stemmed from the desire to improve the state of threshold signature research to match the needs of Zcash users today. Specifically, we needed to ensure that performing multi-party signing operations could be both performant, secure, and indistinguishable from transactions signed by only a single party. 

Further, we wanted to ensure that users could perform threshold signing operations (such that out of N authorized signers, only T need to participate in the signing protocol to issue a valid signature, where T< N), as such designs allow for greater redundancy and failure recovery in the case that a share is lost or one participant cannot (or refuses to) participate in the signing operation.

• What are the benefits of using FROST over other Schnorr-based threshold signature protocols?

1. Low round complexity in both the distributed key-generation and signing phases. The distributed key generation phase can be completed in 2 rounds. The signing phase can be completed in less or equal to 3 rounds depending on whether we use a signature aggregator role and a preprocessing stage. 
2. Concurrent security. The signing phase is secure when performed concurrently. That is, an unlimited number of signature operations can be performed in parallel. In contrast with other threshold Schnorr signature protocols, there are existing Schnorr-based threshold signature protocols, such as [GJKR03, SS01], that have the same round complexity, but they suffer from limited concurrency to protect against the attack of Drijvers et al. [DEF19].
3. Secure against dishonest majority. FROST is secure against adversaries which control up to t-1 signers in the signing phase.
4. Simple cryptographic building blocks and assumptions. FROST is built upon the threshold Shamir secret sharing and Feldman verifiable secret sharing schemes and it relies only on the discrete logarithm assumption.

• What stage of development is FROST currently in?

FROST is a proposed IETF standard, on the path towards adoption and standardization. Industry leaders such as Coinbase are looking into bringing it into production. 

• How can I report security issues?

Our community members can report security issues by emailing us at security@zfnd.org. 

• How can I give feedback to the engineering team?

Feedback on our work can be emailed to engineers@zfnd.org. We rely on your feedback to improve our work and we thank you in advance for it.