X.509 certificate token profile URIs.
X.509 v3 certificate token type
"#{BASE_URI}/oasis-200401-wss-x509-token-profile-1.0#X509v3".freeze
X.509 Subject Key Identifier reference type
"#{BASE_URI}/oasis-200401-wss-x509-token-profile-1.0#X509SubjectKeyIdentifier".freeze