keyservers

Keyservers are servers that store and distribute public keys used in OpenPGP and related cryptographic systems. They provide a shared repository of public keys, including user IDs and signatures, enabling users to fetch keys in order to encrypt messages or verify signatures. They do not store private keys and rely on the key owner’s control of the corresponding secret material.

Most keyservers implement the OpenPGP public key server protocol, historically through the Synchronizing Key Server (SKS) network and its HTTP Keyserver Protocol (HKP). Clients can search by user ID, email address, key fingerprint, or key ID and download public key material to import into a local keyring. Users may upload public keys and revocation certificates to a keyserver so the key is propagated across the network; however, the keyserver does not vouch for the identity or trustworthiness of the key owner.

Privacy and trust considerations accompany keyserver use. Key records link identity data to public keys, so server activity can reveal personal information; modern deployments may emphasize minimizing exposure and encourage verifying key fingerprints through out-of-band channels. Administrators may implement measures to curb abuse, such as rate limiting. Despite potential privacy concerns, keyservers remain a convenient mechanism for key discovery and distribution, with emphasis on verification by the user.

Notable deployments include networks based on the SKS reference implementation and newer services such as keys.openpgp.org and keyserver.ubuntu.com. End users often rely on a combination of widely used servers or centralized mirrors to ensure broader accessibility and redundancy of key data.