Time stamp protocol
|Internet protocol suite|
The Time-Stamp Protocol, or TSP is a cryptographic protocol for certifying timestamps using X.509 certificates and public key infrastructure. The timestamp is the signer's assertion that a piece of electronic data existed at or before a particular time.
- IETF RFC 3161, official specification
- IETF RFC 5816, ESSCertIDv2 Update for RFC 3161
-  Documentation for the OpenSSL
- OpenTSA was an open-source project to add time stamping functionalities to OpenSSL. (Archived July 12, 2012, at the Wayback Machine)