SPKIpin

SPKIpin is a term used to describe a mechanism for pinning SPKI (Simple Public Key Infrastructure) public key information to improve trust and security in PKI deployments. In this concept, clients maintain a set of approved SPKI fingerprints and rely on those fingerprints to validate certificates presented during a connection. SPKIpin aims to reduce the risk posed by compromised certificate authorities or misissued certificates by tying trust to specific SPKI values rather than solely to a certificate chain.

SPKI, developed as an alternative to traditional X.509 PKI, emphasizes authorization and delegation using certificates that convey simple, verifiable assertions about keys and permissions. SPKIpin extends this approach by anchoring trust to a known SPKI fingerprint for a service or authority. When a connection is established, the client computes the SPKI fingerprint of the presented certificate and compares it against the pinned set. A match permits the connection, while a mismatch results in rejection or additional verification steps.

Implementation considerations include how pins are distributed, updated, and rotated without causing service outages. Pins can be scoped to domains or services, and rotation typically requires support for multiple allowed keys during a transition. SPKIpin also introduces maintenance and interoperability challenges, as pinning policies vary and may not be standardized across platforms.

In summary, SPKIpin represents a pinning approach within SPKI to enhance trust by binding connections to specific SPKI fingerprints, while acknowledging practical challenges in deployment and key rotation. See also certificate pinning and SPKI concepts.