“The public key of a natural person is a unique identifier and its use in online services is generally associated with other types of information that make it possible to identify and profile the person holding such a key. Under these conditions, the public key is personal data that uniquely identifies a person and thus its processing is subject to the provisions of the GDPR, although it can be considered as a method of pseudonymisation insofar as it can conceal a person’s real name.”
https://www.aepd.es/en/prensa-y-comunicacion/blog/encryption-and-privacy-v-the-key-as-personal-data