# Appendix E: Reserved numbers We reserve these certificate type values for Ed25519 certificates: ```text [08] short-term descriptor signing key, signed with blinded public key. (Section 2.4) [09] intro point authentication key, cross-certifying the descriptor signing key. (Section 2.5) [0B] ed25519 key derived from the curve25519 intro point encryption key, cross-certifying the descriptor signing key. (Section 2.5) Note: The value "0A" is skipped because it's reserved for the onion key cross-certifying ntor identity key from proposal 228. ```