What Is FROST Protocol?
Also known as: FROST, Flexible Round-Optimized Schnorr Threshold, FROST Threshold Signature
In short
FROST (Flexible Round-Optimized Schnorr Threshold) is a threshold signature protocol that lets multiple parties produce a joint, standard-looking Schnorr signature once a set threshold is reached, without ever assembling a single private key.
FROST (Flexible Round-Optimized Schnorr Threshold) was proposed in 2020 by cryptographers Chelsea Komlo and Ian Goldberg. It works in a “t-of-n” structure: for example, a valid signature can be produced when any three of five participants come together. The key is split into shares through distributed key generation (DKG) or a trusted dealer, and each participant holds only their own share. The protocol reduces the signing process to two rounds, so it requires less communication than earlier threshold Schnorr schemes.
The resulting signature is indistinguishable from a Schnorr signature produced by a single person. When combined with the Schnorr signatures that came to Bitcoin with Taproot, this provides an important advantage: unlike in classic multisig structures, each signer does not need to be recorded on the chain separately; this reduces transaction size and fees, and how many people manage the wallet is also not visible from the outside.
FROST has been standardized by the IETF; it is used or being developed in institutional custody solutions, multi-party computation (MPC) based wallets, and projects such as Zcash. Its security depends on the implementation being done correctly and on participants protecting their key shares well.
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