Lijun,
I know I will need multiple messages and then a FEC.
For the TESLA Signed Key Disclouser message, I am able to pack that all
into 2 packets then the FEC is a simple XOR (recover 1 lost packet).
Here I am hope I can do it in 4 or 5 and then use the EVENODD FEC
(recover 2 lost packets).
I am having SOOO much fun on this! I have a deadline of Feb 28 to have
it written in a "final form" to present week of Mar 9. :)
Right now the design is closed, but IF I this going, there will be
public IETF ID, as there is much needing proper review. ;)
On 2/11/26 3:14 PM, Lijun Liao wrote:
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
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