[BUG] Endianness mismatch in Key exchange from Conformance Owner

[Sai-Anudeep47]

to2_endianness_logs.txt

What part of the spec are you testing?

• [ ] Rendezvous Server
• [ ] Device Onboarding Service
• [x] Device Implementation

What protocol are having issue with?

• [ ] TO0
• [ ] TO1
• [x] TO2

Issue description

It is observed during message 61, 'xAKeyExchange' field is sent by conformance owner is in Little Endian format due to which client is unable to decode and throwing at message 64.

Expected value - '0020' Actual value - '2000'

This is also related to #24

Resolved by changing all occurrences of "LittleEndian" to "BigEndian" in

core/shared/kex.crypto.go

[Sai-Anudeep47]

@herrjemand Issue still persists when using SECP256R1 attestation type and observed the fix is provided only for SECP384R1 and is still using Little-endian for SECP256R1 at https://github.com/fido-alliance/fdo-fido-conformance-server/blob/main/core/shared/kex.crypto.go#L149

[yackermann]

Yes. Correct. Sorry. Addressed