Signet rings are used to authenticate documents by pressing the ring's face into melted wax. The document is then "under seal."
Encryption and Security Certificates
This guide discusses encryption, which is the intended transformation of information into apparently illegible form, and security certificates. These are key components of Public Key Infrastructure (PKI), which underlies the secure transmission and storage of data in digital form. These tools allow secure, confidential sharing of information, and authentication of information as to provenance and content.