HI Robert, Do you have only one piece of 385-bit or multiple pieces?
One piece of 385-bit seems impossible here. For the cryptographic parts you need 256+512 bits (Ed25519 public key: 256 bits, and Ed25519 signature: 64 bytes). Lijun > On 11. Feb 2026, at 16:32, Robert Moskowitz > <[email protected]> wrote: > > I have to squeeze only those fields into as few 385-bit pieces to validate a > TESLA Key Disclouser. > > Ugh. > > So "all" I need from the aircraft full certificate (ignore all those policy > OIDs and other odds and ends!) is: > > Validity dates > issuerAltName (IAN) IPv6 (issuer's DET per rfc9374) > subjectAltName (SAN) IPv6 (aircraft's DET per rfc9374) > subjectAltName (SAN) IPv4 (aircraft's 24-bit number prefixed with ZERO) - > note I have not figured out any better/smaller OID (in subject or SAN) for > the 24-bit aircraft number. Using IPv4 is a hack at best. > Aircraft's EdDSA25519 public key > CBOR sig of these by issuer's EdDSA25519 key > > Note that the issuer DET's SuiteID provides the algorithm for the signature. > > I am trying to use cbor.me to expand some test cbor c509 certs to get sizes, > but I am not good enough with cbor to figure this out. Plus that sig would > probably be a "regular" cbor object signature, not the c509 sig. > > I am under a deadline with a bunch of other writing that this is just one > important part, so any help is greatly appreciated. > > Each 385-bit message costs 120ms of channel capacity. The fewer the better... > > Bob > > _______________________________________________ > COSE mailing list -- [email protected] > To unsubscribe send an email to [email protected]
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