EXT000E: Encrypted AES-256-CBC

• Extension dependencies: none
• Document status: Testing

Full encryption using AES 256 CBC with single key buffer for requests and responses. Key exchange via other extensions.

Commands

0018 Send Encrypted Request

Devices supporting this return error 0006 for non-wrapped commands except Handshake, KeepAlive, and encryption setup (e.g., EXT0009).

Request/Response:

<TID> 3900 <LEN> 0018 <PAYLOAD>

PAYLOAD Format

<LEN> <CMD> <DATA> <CHKSUM> <PADDING>

Field	Length	Description
LEN	2 bytes	Length of CMD + DATA
CMD	2 bytes	Command code
DATA	variable	Data field
CHKSUM	2 bytes	Byte sum of CMD + DATA
PADDING	multiple of 16	Random bytes (min 128 total PAYLOAD)

Errors

Decryption error (unencrypted):

<TID> 3900 0004 8018 0010

All other errors are encrypted within PAYLOAD. If client can’t decrypt response, it must terminate connection.