X-only Public Key
cryptography · bitcoin
A 32-byte public key format that stores only the x-coordinate, used by BIP340 Schnorr signatures and Taproot.
An x-only public key omits the usual prefix byte that identifies which y-coordinate parity belongs to the elliptic curve point. BIP340 defines verification rules so the missing parity is handled consistently.
X-only keys simplify Taproot and Schnorr constructions and save a small amount of space. Wallets and libraries must still handle key tweaking and parity correctly to produce valid signatures.
Related terms
Schnorr Signatures
→A digital signature scheme with linear properties that can improve verification, multi-signature design, and privacy.
bch · scaling
Taproot
→A Bitcoin upgrade that enables more private and efficient spending using Schnorr signatures and script path commitments.
btc · upgrade
Public Key
→Cryptographic data used to verify signatures made by the corresponding private key.
cryptography · technical