Certificate Expectation Assertions (CEA)

This document specifies Certificate Expectation Assertions (CEA), a DNS-based mechanism enabling domain owners to publish expected certificate authority identities for their domains. Clients can compare observed TLS certificates against these published expectations to identify potential unauthorized interception. CEA uses DNSSEC-signed DNS TXT records, supports multiple certificate authorities, and employs fail-open transparency rather than blocking connections. This approach differs from HPKP's fail-secure model and provides an optional mechanism for interception detection. This document is published as Informational to document the CEA protocol for experimental deployment. It does not modify TLS or PKI infrastructure and is not an IETF standard. This is an experimental specification that has not been endorsed by any IETF Working Group and does not represent IETF consensus. Note: This document does not modify the TLS protocol (RFC 8446), certificate validation procedures (RFC 5280), or PKI infrastructure. CEA is an optional client-side transparency overlay that provides additional information to users. Implementations that do not support CEA continue to function normally with no changes to TLS behavior.