Room server identity_key rejects 64-byte MeshCore firmware keys

[NederWeb]

When importing a private key exported from an official MeshCore Room Server firmware device, pyMC_Repeater silently skips the room server with only a log error:

Identity key for 'MyRoom' is invalid length: 64 bytes (expected 32)

Root cause

MeshCore firmware exports private keys in a 64-byte expanded format: [32-byte scalar][32-byte nonce] (128 hex characters). The room server identity loader in main.py strictly
requires 32 bytes and discards any other length.

The fix is a one-line change — allow 64-byte keys to pass through:

Before

if len(identity_key_bytes) != 32:

After

if len(identity_key_bytes) not in (32, 64):

Why simply truncating to 32 bytes does not work

LocalIdentity(seed=bytes) behaves differently depending on length:

• 32 bytes → treated as a standard PyNaCl seed, SHA-512 hashed internally → produces a different public key
• 64 bytes → treated as a MeshCore expanded key, derives public key via crypto_scalarmult_ed25519_base_noclamp (no hashing) → matches the firmware identity

LocalIdentity already correctly handles the 64-byte format. The room server loader just needs to let it through.

Steps to reproduce

1. Export the private key from a MeshCore Room Server firmware device (64-byte / 128 hex char key)
2. Add it as identity_key under identities.room_servers in config.yaml
3. Start pyMC_Repeater — the room server is skipped

Expected behaviour

The room server loads with the same public key and node address as the original firmware device.