Independent Submission M.J. Arcan Internet-Draft Arcan Consulting Intended status: Experimental 10 January 2026 Expires: 14 July 2026 The MyClerk Protocol: Tiered Security Communication for Distributed Family Systems draft-myclerk-protocol-01 Abstract This document specifies the MyClerk Protocol, a tiered-security communication protocol designed for distributed family orchestration systems. The protocol provides six security tiers ranging from 1-byte minimal overhead for tunneled messages to 144-byte full security for critical operations. It supports multiple transport mechanisms including NATS, Matrix, WebSocket, and direct TCP, while maintaining end-to-end encryption using ChaCha20-Poly1305 and X25519 key exchange. The protocol is transport-agnostic, federation-capable, and optimized for environments ranging from resource-constrained IoT devices to full-featured desktop clients. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 14 July 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Arcan Expires 14 July 2026 [Page 1] Internet-Draft MyClerk Protocol January 2026 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Design Goals . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Security Tiers Overview . . . . . . . . . . . . . . . . . 4 3. Message Format . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Common Header Fields . . . . . . . . . . . . . . . . . . 5 3.2. Tier 0 Header (1 byte) . . . . . . . . . . . . . . . . . 5 3.3. Tier 1 Header (4 bytes) . . . . . . . . . . . . . . . . . 6 3.4. Tier 2 Header (6 bytes) . . . . . . . . . . . . . . . . . 6 3.5. Tier 3 Header (12 bytes) . . . . . . . . . . . . . . . . 6 3.6. Tier 4 Header (42 bytes) . . . . . . . . . . . . . . . . 7 3.7. Tier 5 Header (58 bytes) . . . . . . . . . . . . . . . . 7 4. Nonce Construction . . . . . . . . . . . . . . . . . . . . . 8 5. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. ECDH Key Exchange . . . . . . . . . . . . . . . . . . . . 8 5.2. Key Rotation . . . . . . . . . . . . . . . . . . . . . . 9 6. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 9 6.1. Core Operations (0x0000-0x00FF) . . . . . . . . . . . . . 10 6.1.1. Session Management (0x0000-0x000F) . . . . . . . . . 10 6.1.2. Key Management (0x0010-0x001F) . . . . . . . . . . . 11 6.2. Resource Sharing Operations (0x0200-0x02FF) . . . . . . . 11 6.2.1. Device Management (0x0200-0x020F) . . . . . . . . . . 11 6.2.2. Stream Operations (0x0210-0x021F) . . . . . . . . . . 12 6.2.3. GPU Service Operations (0x0220-0x022F) . . . . . . . 12 6.2.4. Dynamic Routing and ACL (0x0240-0x024F) . . . . . . . 13 6.3. Hardware Passthrough Operations (0x0600-0x06FF) . . . . . 14 6.3.1. USB Operations (0x0600-0x060F) . . . . . . . . . . . 14 6.3.2. Serial Operations (0x0610-0x061F) . . . . . . . . . . 15 6.3.3. GPIO Operations (0x0620-0x062F) . . . . . . . . . . . 16 6.3.4. I2C Operations (0x0630-0x063F) . . . . . . . . . . . 17 6.3.5. SPI Operations (0x0640-0x064F) . . . . . . . . . . . 18 6.3.6. CAN Bus Operations (0x0650-0x065F) . . . . . . . . . 19 6.3.7. 1-Wire Operations (0x0660-0x066F) . . . . . . . . . . 19 7. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 20 7.1. SESSION_INIT Payload . . . . . . . . . . . . . . . . . . 20 7.2. SESSION_ACK Payload . . . . . . . . . . . . . . . . . . . 21 7.3. SESSION_RESUME Payload . . . . . . . . . . . . . . . . . 21 8. Tier Compatibility . . . . . . . . . . . . . . . . . . . . . 21 Arcan Expires 14 July 2026 [Page 2] Internet-Draft MyClerk Protocol January 2026 8.1. Minimum Tier Requirements . . . . . . . . . . . . . . . . 21 9. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 22 9.1. Specific Error Codes . . . . . . . . . . . . . . . . . . 22 10. Security Considerations . . . . . . . . . . . . . . . . . . . 23 10.1. Nonce Reuse . . . . . . . . . . . . . . . . . . . . . . 23 10.2. Replay Protection . . . . . . . . . . . . . . . . . . . 23 10.3. Tier Downgrade Attacks . . . . . . . . . . . . . . . . . 23 10.4. Key Compromise . . . . . . . . . . . . . . . . . . . . . 23 10.5. Post-Quantum Considerations . . . . . . . . . . . . . . 23 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 12.1. Normative References . . . . . . . . . . . . . . . . . . 24 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 25 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 25 1. Introduction Modern families operate across multiple locations and devices: a primary home with network-attached storage, a vacation house with a mini-PC, grandparents with a Raspberry Pi, and mobile devices requiring access while traveling. The MyClerk Protocol addresses the communication requirements of such distributed family systems. Traditional protocols impose significant overhead that becomes problematic for constrained channels. The MyClerk Protocol introduces tiered security levels, allowing applications to select appropriate overhead based on the security requirements of each operation. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 1.2. Terminology Node A device participating in a MyClerk deployment, such as a server, desktop client, mobile device, or IoT device. Core Node A node classified as stable and reliable, expected to maintain high availability (>95% uptime over 30 days). Bonus Node A node with variable availability, used opportunistically for additional redundancy. Arcan Expires 14 July 2026 [Page 3] Internet-Draft MyClerk Protocol January 2026 Family A group of users and nodes sharing a common trust domain and cryptographic key hierarchy. Federation The interconnection of multiple families for resource sharing or communication. Tier A security level (0-5) determining the header structure and cryptographic protections applied to a message. Session A stateful connection between two endpoints with established cryptographic keys. 2. Protocol Overview The MyClerk Protocol is a binary protocol using MessagePack [RFC8949] for payload encoding. It defines six security tiers with increasing header sizes and cryptographic protections. 2.1. Design Goals 1. *Tiered Security:* 1-144 bytes overhead depending on security requirements. 2. *Transport Agnostic:* Operates over NATS, Matrix, WebSocket, TCP, or other transports. 3. *Federation Ready:* Supports multi-server, multi-family deployments. 4. *Future Proof:* Extensible operations and feature negotiation. 2.2. Security Tiers Overview +====+======+===================+================+=================+ |Tier|Header| Encryption | Authentication | Use Case | | |Size | | | | +====+======+===================+================+=================+ |0 |1 byte| None (tunneled) | None | Inside secure | | | | | | session | +----+------+-------------------+----------------+-----------------+ |1 |4 | None | None | Fire-and-forget | | |bytes | | | commands | +----+------+-------------------+----------------+-----------------+ |2 |6 | Optional | CRC-16 | Home automation | | |bytes | | | | +----+------+-------------------+----------------+-----------------+ |3 |12 | ChaCha20-Poly1305 | HMAC-32 | Conversational | | |bytes | | | | Arcan Expires 14 July 2026 [Page 4] Internet-Draft MyClerk Protocol January 2026 +----+------+-------------------+----------------+-----------------+ |4 |42 | ChaCha20-Poly1305 | HMAC-64 | Key exchange | | |bytes | | | | +----+------+-------------------+----------------+-----------------+ |5 |58+ | ChaCha20-Poly1305 | HMAC-256 + | Maximum | | |bytes | | Poly1305 | security | +----+------+-------------------+----------------+-----------------+ Table 1: Security Tier Summary 3. Message Format All messages consist of a header, optional payload, and optional trailer. The header format varies by security tier. 3.1. Common Header Fields The first byte (Flags) is present in all tiers and has the following structure: 0 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V V|T T T|C|F|E| +-+-+-+-+-+-+-+-+ V: Protocol Version (2 bits) - Currently 0 T: Security Tier (3 bits) - Values 0-5 C: Compressed (1 bit) - Payload is compressed F: Fragmented (1 bit) - Message is fragmented E: Encrypted (1 bit) - Payload is encrypted 3.2. Tier 0 Header (1 byte) Tier 0 is used for messages tunneled inside an already-secure session. It provides minimal overhead. 0 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |0 0|0 0 0|C|F|E| +-+-+-+-+-+-+-+-+ Tier 0 messages MUST only be sent within an established Tier 3+ session. Implementations receiving a Tier 0 message outside of a secure session MUST discard it. Arcan Expires 14 July 2026 [Page 5] Internet-Draft MyClerk Protocol January 2026 3.3. Tier 1 Header (4 bytes) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V V|0 0 1|C|F|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Operation Code (16 bits) Identifies the operation. See Section 6. Sequence (8 bits) Message sequence number, wrapping at 255. 3.4. Tier 2 Header (6 bytes) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V V|0 1 0|C|F|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Session ID (16 bits) Identifies the session context for this message. Tier 2 messages SHOULD include a CRC-16 trailer for error detection. 3.5. Tier 3 Header (12 bytes) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V V|0 1 1|C|F|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp (cont.) | Nonce | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Timestamp (32 bits) Unix timestamp in seconds. Used for replay protection. Nonce (16 bits) Random nonce component. Combined with timestamp and counter to form the full 96-bit nonce for ChaCha20-Poly1305. Tier 3 messages with the E flag set MUST be encrypted using ChaCha20-Poly1305 as specified in [RFC8439]. Arcan Expires 14 July 2026 [Page 6] Internet-Draft MyClerk Protocol January 2026 3.6. Tier 4 Header (42 bytes) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V V|1 0 0|C|F|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp (cont.) | Nonce | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Key ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | ECDH Public Key (X25519) | | (32 bytes) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Key ID (32 bits) Identifier for the key being used or negotiated. ECDH Public Key (256 bits) X25519 public key as specified in [RFC7748]. 3.7. Tier 5 Header (58 bytes) Tier 5 extends Tier 4 with a full Poly1305 authentication tag in the header: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | [Tier 4 Header - 42 bytes] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Poly1305 Tag (16 bytes) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Tier 5 messages MUST include a full HMAC-SHA256 (32 bytes) in the trailer, providing dual authentication: Poly1305 for AEAD integrity and HMAC-SHA256 for post-quantum resistance. Arcan Expires 14 July 2026 [Page 7] Internet-Draft MyClerk Protocol January 2026 4. Nonce Construction ChaCha20-Poly1305 requires a 96-bit (12-byte) nonce that MUST NOT be reused with the same key. The MyClerk Protocol constructs nonces as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Random (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Counter (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Timestamp (32 bits) Unix epoch seconds. Provides cross-session replay protection. Random (32 bits) Cryptographically random value generated per session using a CSPRNG. Provides 2^32 possible values per second. Counter (32 bits) Per-message counter starting at 0, incremented for each message. Allows 2^32 messages per session. All fields are encoded in big-endian byte order. This construction provides a collision probability of less than 2^-80 per year at 1 million operations per second, assuming proper CSPRNG implementation. 5. Key Derivation Session keys are derived using HKDF as specified in [RFC5869] with SHA-256 as the hash function. 5.1. ECDH Key Exchange For Tier 4+ sessions: shared_secret = X25519(local_private_key, remote_public_key) session_key = HKDF-SHA256( IKM = shared_secret, salt = nonce_initiator || nonce_responder, info = "myclerk-session-v0", L = 32 ) Arcan Expires 14 July 2026 [Page 8] Internet-Draft MyClerk Protocol January 2026 5.2. Key Rotation Keys MUST be rotated after any of the following conditions: * 2^32 messages sent (nonce exhaustion) * 24 hours elapsed (time-based) * Explicit KEY_ROTATE operation received Rotated keys are derived as: new_key = HKDF-SHA256( IKM = current_key, salt = "rotate", info = rotation_counter (4 bytes, big-endian), L = 32 ) 6. Protocol Operations Operations are identified by a 16-bit operation code. The operation space is divided into ranges: Arcan Expires 14 July 2026 [Page 9] Internet-Draft MyClerk Protocol January 2026 +===============+===================================================+ | Range | Category | +===============+===================================================+ | 0x0000-0x00FF | Core Operations (Session, Key Management) | +---------------+---------------------------------------------------+ | 0x0100-0x01FF | Standard Operations (Device, Identity, | | | Messaging) | +---------------+---------------------------------------------------+ | 0x0200-0x02FF | Resource Sharing (Streams, GPU, Routing) | +---------------+---------------------------------------------------+ | 0x0300-0x03FF | Federation | +---------------+---------------------------------------------------+ | 0x0400-0x04FF | Billing and Economics | +---------------+---------------------------------------------------+ | 0x0500-0x05FF | Virtual File System (VFS) | +---------------+---------------------------------------------------+ | 0x0600-0x06FF | Hardware Passthrough (USB, GPIO, I2C, | | | SPI, CAN) | +---------------+---------------------------------------------------+ | 0xF000-0xFFFE | Vendor Extensions | +---------------+---------------------------------------------------+ | 0xFFFF | Reserved | +---------------+---------------------------------------------------+ Table 2: Operation Code Ranges 6.1. Core Operations (0x0000-0x00FF) 6.1.1. Session Management (0x0000-0x000F) +========+===================+============================+ | Code | Name | Description | +========+===================+============================+ | 0x0000 | NOP | No operation | +--------+-------------------+----------------------------+ | 0x0001 | KEEPALIVE | Session keepalive | +--------+-------------------+----------------------------+ | 0x0002 | KEEPALIVE_ACK | Keepalive acknowledgment | +--------+-------------------+----------------------------+ | 0x0003 | SESSION_INIT | Initialize session | +--------+-------------------+----------------------------+ | 0x0004 | SESSION_ACK | Session acknowledgment | +--------+-------------------+----------------------------+ | 0x0005 | SESSION_CLOSE | Close session | +--------+-------------------+----------------------------+ | 0x0006 | SESSION_CLOSE_ACK | Close acknowledgment | +--------+-------------------+----------------------------+ | 0x0007 | SESSION_RESUME | Resume session with ticket | Arcan Expires 14 July 2026 [Page 10] Internet-Draft MyClerk Protocol January 2026 +--------+-------------------+----------------------------+ | 0x0008 | SESSION_RESUMED | Session resumed | +--------+-------------------+----------------------------+ Table 3: Session Management Operations 6.1.2. Key Management (0x0010-0x001F) +========+=======================+=======================+ | Code | Name | Description | +========+=======================+=======================+ | 0x0010 | KEY_EXCHANGE_INIT | Initiate key exchange | +--------+-----------------------+-----------------------+ | 0x0011 | KEY_EXCHANGE_RESPONSE | Key exchange response | +--------+-----------------------+-----------------------+ | 0x0012 | KEY_EXCHANGE_COMPLETE | Key exchange complete | +--------+-----------------------+-----------------------+ | 0x0016 | SESSION_ROTATE | Rotate session key | +--------+-----------------------+-----------------------+ | 0x0017 | SESSION_REVOKE | Revoke session key | +--------+-----------------------+-----------------------+ Table 4: Key Management Operations 6.2. Resource Sharing Operations (0x0200-0x02FF) Resource Sharing operations enable devices to expose and consume resources across the network. These operations support video, audio, HID, and GPU services. 6.2.1. Device Management (0x0200-0x020F) +========+=====================+===============================+ | Code | Name | Description | +========+=====================+===============================+ | 0x0200 | DEVICE_LIST | List available devices | +--------+---------------------+-------------------------------+ | 0x0201 | DEVICE_INFO | Get device information | +--------+---------------------+-------------------------------+ | 0x0202 | DEVICE_SUBSCRIBE | Subscribe to device events | +--------+---------------------+-------------------------------+ | 0x0203 | DEVICE_UNSUBSCRIBE | Unsubscribe from device | +--------+---------------------+-------------------------------+ | 0x0204 | DEVICE_LOCK | Lock device for exclusive use | +--------+---------------------+-------------------------------+ | 0x0205 | DEVICE_UNLOCK | Release device lock | +--------+---------------------+-------------------------------+ | 0x0206 | DEVICE_CONFIGURE | Configure device parameters | Arcan Expires 14 July 2026 [Page 11] Internet-Draft MyClerk Protocol January 2026 +--------+---------------------+-------------------------------+ | 0x0207 | DEVICE_CAPABILITIES | Query device capabilities | +--------+---------------------+-------------------------------+ Table 5: Device Management Operations 6.2.2. Stream Operations (0x0210-0x021F) +========+==================+=============================+ | Code | Name | Description | +========+==================+=============================+ | 0x0210 | STREAM_START | Start data stream | +--------+------------------+-----------------------------+ | 0x0211 | STREAM_STOP | Stop data stream | +--------+------------------+-----------------------------+ | 0x0212 | STREAM_DATA | Stream data payload | +--------+------------------+-----------------------------+ | 0x0213 | STREAM_CONFIGURE | Configure stream parameters | +--------+------------------+-----------------------------+ | 0x0214 | STREAM_QUALITY | Adjust quality settings | +--------+------------------+-----------------------------+ | 0x0215 | STREAM_PAUSE | Pause stream | +--------+------------------+-----------------------------+ | 0x0216 | STREAM_RESUME | Resume paused stream | +--------+------------------+-----------------------------+ Table 6: Stream Operations Stream types are indicated in the STREAM_START payload: * 0x01: Video (H.264, MJPEG) * 0x02: Audio (Opus, PCM) * 0x03: HID (evdev events) * 0x04: Serial (byte stream) 6.2.3. GPU Service Operations (0x0220-0x022F) GPU operations enable queue-based access to inference services (LLM, TTS, STT, Image Generation). Arcan Expires 14 July 2026 [Page 12] Internet-Draft MyClerk Protocol January 2026 +========+================+==========================+ | Code | Name | Description | +========+================+==========================+ | 0x0220 | GPU_REQUEST | Submit GPU request | +--------+----------------+--------------------------+ | 0x0221 | GPU_RESPONSE | GPU response (streaming) | +--------+----------------+--------------------------+ | 0x0222 | GPU_STATUS | Query service status | +--------+----------------+--------------------------+ | 0x0223 | GPU_CANCEL | Cancel pending request | +--------+----------------+--------------------------+ | 0x0224 | GPU_QUEUE_INFO | Queue position and ETA | +--------+----------------+--------------------------+ Table 7: GPU Service Operations GPU service types: * 0x01: LLM (Large Language Model) * 0x02: TTS (Text-to-Speech) * 0x03: STT (Speech-to-Text) * 0x04: ImageGen (Image Generation) 6.2.4. Dynamic Routing and ACL (0x0240-0x024F) Dynamic routing enables Hub-controlled device assignment and per- client access control. A Hub can redirect device streams between clients dynamically. Arcan Expires 14 July 2026 [Page 13] Internet-Draft MyClerk Protocol January 2026 +========+================+=======================+ | Code | Name | Description | +========+================+=======================+ | 0x0240 | ROUTE_CREATE | Create device route | +--------+----------------+-----------------------+ | 0x0241 | ROUTE_DELETE | Delete device route | +--------+----------------+-----------------------+ | 0x0242 | ROUTE_LIST | List active routes | +--------+----------------+-----------------------+ | 0x0243 | ROUTE_MODIFY | Modify existing route | +--------+----------------+-----------------------+ | 0x0244 | ACL_SET | Set access control | +--------+----------------+-----------------------+ | 0x0245 | ACL_GET | Get access control | +--------+----------------+-----------------------+ | 0x0246 | ACL_GRANT | Grant client access | +--------+----------------+-----------------------+ | 0x0247 | ACL_REVOKE | Revoke client access | +--------+----------------+-----------------------+ | 0x0248 | ROUTE_PRIORITY | Set routing priority | +--------+----------------+-----------------------+ Table 8: Dynamic Routing Operations Access modes: * 0x00: None (no access) * 0x01: Read-only * 0x02: Write-only * 0x03: Read-write * 0x04: Exclusive (single client) 6.3. Hardware Passthrough Operations (0x0600-0x06FF) Hardware Passthrough operations enable low-level access to hardware interfaces. Unlike service-based resource sharing, these operations provide direct protocol-level access to hardware buses. 6.3.1. USB Operations (0x0600-0x060F) USB passthrough virtualizes USB at the URB (USB Request Block) level, allowing any USB device to appear as natively connected on the client. Arcan Expires 14 July 2026 [Page 14] Internet-Draft MyClerk Protocol January 2026 +========+==========================+==========================+ | Code | Name | Description | +========+==========================+==========================+ | 0x0600 | USB_DEVICE_LIST | List USB devices | +--------+--------------------------+--------------------------+ | 0x0601 | USB_DEVICE_ATTACH | Attach USB device | +--------+--------------------------+--------------------------+ | 0x0602 | USB_DEVICE_DETACH | Detach USB device | +--------+--------------------------+--------------------------+ | 0x0603 | USB_CONTROL_TRANSFER | USB control transfer | +--------+--------------------------+--------------------------+ | 0x0604 | USB_BULK_TRANSFER | USB bulk transfer | +--------+--------------------------+--------------------------+ | 0x0605 | USB_INTERRUPT_TRANSFER | USB interrupt transfer | +--------+--------------------------+--------------------------+ | 0x0606 | USB_ISOCHRONOUS_TRANSFER | USB isochronous transfer | +--------+--------------------------+--------------------------+ | 0x0607 | USB_GET_DESCRIPTOR | Get USB descriptor | +--------+--------------------------+--------------------------+ | 0x0608 | USB_SET_CONFIGURATION | Set USB configuration | +--------+--------------------------+--------------------------+ | 0x0609 | USB_SET_INTERFACE | Set USB interface | +--------+--------------------------+--------------------------+ | 0x060A | USB_CLEAR_HALT | Clear endpoint halt | +--------+--------------------------+--------------------------+ | 0x060B | USB_RESET | Reset USB device | +--------+--------------------------+--------------------------+ Table 9: USB Operations 6.3.2. Serial Operations (0x0610-0x061F) Serial passthrough supports RS-232, RS-485, and UART interfaces. Arcan Expires 14 July 2026 [Page 15] Internet-Draft MyClerk Protocol January 2026 +========+=======================+==============================+ | Code | Name | Description | +========+=======================+==============================+ | 0x0610 | SERIAL_PORT_LIST | List serial ports | +--------+-----------------------+------------------------------+ | 0x0611 | SERIAL_PORT_OPEN | Open serial port | +--------+-----------------------+------------------------------+ | 0x0612 | SERIAL_PORT_CLOSE | Close serial port | +--------+-----------------------+------------------------------+ | 0x0613 | SERIAL_PORT_CONFIGURE | Configure baud, parity, etc. | +--------+-----------------------+------------------------------+ | 0x0614 | SERIAL_DATA_WRITE | Write to serial port | +--------+-----------------------+------------------------------+ | 0x0615 | SERIAL_DATA_READ | Read from serial port | +--------+-----------------------+------------------------------+ | 0x0616 | SERIAL_CONTROL_SET | Set control lines (DTR, RTS) | +--------+-----------------------+------------------------------+ | 0x0617 | SERIAL_CONTROL_GET | Get control line status | +--------+-----------------------+------------------------------+ | 0x0618 | SERIAL_BREAK | Send break condition | +--------+-----------------------+------------------------------+ Table 10: Serial Operations 6.3.3. GPIO Operations (0x0620-0x062F) GPIO operations enable control of General Purpose Input/Output pins. Arcan Expires 14 July 2026 [Page 16] Internet-Draft MyClerk Protocol January 2026 +========+====================+==============================+ | Code | Name | Description | +========+====================+==============================+ | 0x0620 | GPIO_CHIP_LIST | List GPIO chips | +--------+--------------------+------------------------------+ | 0x0621 | GPIO_LINE_INFO | Get line information | +--------+--------------------+------------------------------+ | 0x0622 | GPIO_LINE_REQUEST | Request GPIO line | +--------+--------------------+------------------------------+ | 0x0623 | GPIO_LINE_RELEASE | Release GPIO line | +--------+--------------------+------------------------------+ | 0x0624 | GPIO_LINE_SET | Set line value | +--------+--------------------+------------------------------+ | 0x0625 | GPIO_LINE_GET | Get line value | +--------+--------------------+------------------------------+ | 0x0626 | GPIO_LINE_WATCH | Watch for edge events | +--------+--------------------+------------------------------+ | 0x0627 | GPIO_EVENT | GPIO edge event notification | +--------+--------------------+------------------------------+ | 0x0628 | GPIO_PWM_CONFIGURE | Configure PWM output | +--------+--------------------+------------------------------+ | 0x0629 | GPIO_PWM_SET | Set PWM duty cycle | +--------+--------------------+------------------------------+ Table 11: GPIO Operations 6.3.4. I2C Operations (0x0630-0x063F) I2C (Inter-Integrated Circuit) bus operations for sensor and peripheral communication. Arcan Expires 14 July 2026 [Page 17] Internet-Draft MyClerk Protocol January 2026 +========+===================+=========================+ | Code | Name | Description | +========+===================+=========================+ | 0x0630 | I2C_BUS_LIST | List I2C buses | +--------+-------------------+-------------------------+ | 0x0631 | I2C_BUS_SCAN | Scan for devices on bus | +--------+-------------------+-------------------------+ | 0x0632 | I2C_TRANSFER | I2C read/write transfer | +--------+-------------------+-------------------------+ | 0x0633 | I2C_WRITE_BYTE | Write single byte | +--------+-------------------+-------------------------+ | 0x0634 | I2C_READ_BYTE | Read single byte | +--------+-------------------+-------------------------+ | 0x0635 | I2C_WRITE_BLOCK | Write data block | +--------+-------------------+-------------------------+ | 0x0636 | I2C_READ_BLOCK | Read data block | +--------+-------------------+-------------------------+ | 0x0637 | I2C_SMBUS_COMMAND | SMBus protocol command | +--------+-------------------+-------------------------+ Table 12: I2C Operations 6.3.5. SPI Operations (0x0640-0x064F) SPI (Serial Peripheral Interface) operations for high-speed peripheral communication. +========+==================+=============================+ | Code | Name | Description | +========+==================+=============================+ | 0x0640 | SPI_BUS_LIST | List SPI buses | +--------+------------------+-----------------------------+ | 0x0641 | SPI_DEVICE_OPEN | Open SPI device | +--------+------------------+-----------------------------+ | 0x0642 | SPI_DEVICE_CLOSE | Close SPI device | +--------+------------------+-----------------------------+ | 0x0643 | SPI_CONFIGURE | Configure mode, speed, bits | +--------+------------------+-----------------------------+ | 0x0644 | SPI_TRANSFER | Full-duplex SPI transfer | +--------+------------------+-----------------------------+ | 0x0645 | SPI_WRITE | SPI write-only | +--------+------------------+-----------------------------+ | 0x0646 | SPI_READ | SPI read-only | +--------+------------------+-----------------------------+ Table 13: SPI Operations Arcan Expires 14 July 2026 [Page 18] Internet-Draft MyClerk Protocol January 2026 6.3.6. CAN Bus Operations (0x0650-0x065F) CAN (Controller Area Network) bus operations for automotive and industrial protocols. +========+=====================+=========================+ | Code | Name | Description | +========+=====================+=========================+ | 0x0650 | CAN_INTERFACE_LIST | List CAN interfaces | +--------+---------------------+-------------------------+ | 0x0651 | CAN_INTERFACE_OPEN | Open CAN interface | +--------+---------------------+-------------------------+ | 0x0652 | CAN_INTERFACE_CLOSE | Close CAN interface | +--------+---------------------+-------------------------+ | 0x0653 | CAN_CONFIGURE | Configure bitrate, mode | +--------+---------------------+-------------------------+ | 0x0654 | CAN_FRAME_SEND | Send CAN frame | +--------+---------------------+-------------------------+ | 0x0655 | CAN_FRAME_RECEIVE | Receive CAN frame | +--------+---------------------+-------------------------+ | 0x0656 | CAN_FILTER_SET | Set receive filter | +--------+---------------------+-------------------------+ | 0x0657 | CAN_ERROR_STATUS | Get error counters | +--------+---------------------+-------------------------+ Table 14: CAN Bus Operations 6.3.7. 1-Wire Operations (0x0660-0x066F) 1-Wire bus operations for temperature sensors, iButtons, and similar devices. Arcan Expires 14 July 2026 [Page 19] Internet-Draft MyClerk Protocol January 2026 +========+===================+==========================+ | Code | Name | Description | +========+===================+==========================+ | 0x0660 | ONEWIRE_BUS_LIST | List 1-Wire buses | +--------+-------------------+--------------------------+ | 0x0661 | ONEWIRE_SEARCH | Search for devices | +--------+-------------------+--------------------------+ | 0x0662 | ONEWIRE_RESET | Reset bus | +--------+-------------------+--------------------------+ | 0x0663 | ONEWIRE_READ_ROM | Read device ROM | +--------+-------------------+--------------------------+ | 0x0664 | ONEWIRE_MATCH_ROM | Select device by ROM | +--------+-------------------+--------------------------+ | 0x0665 | ONEWIRE_SKIP_ROM | Skip ROM (single device) | +--------+-------------------+--------------------------+ | 0x0666 | ONEWIRE_READ | Read bytes | +--------+-------------------+--------------------------+ | 0x0667 | ONEWIRE_WRITE | Write bytes | +--------+-------------------+--------------------------+ Table 15: 1-Wire Operations 7. Payload Formats Payloads are encoded using MessagePack (a subset of CBOR). This section defines payload structures using CDDL [RFC8610]. 7.1. SESSION_INIT Payload session-init = { nonce: bstr .size 8, timestamp: uint, ? capabilities: [* capability], ? device-id: bstr .size 16, } capability = &( compression-lz4: 0, compression-zstd: 1, encryption-chacha20: 2, encryption-aes256gcm: 3, fragmentation: 4, streaming: 5, federation: 6, vfs: 8, ) Arcan Expires 14 July 2026 [Page 20] Internet-Draft MyClerk Protocol January 2026 7.2. SESSION_ACK Payload session-ack = { session-id: uint .size 2, nonce: bstr .size 8, selected-tier: uint .le 5, ? selected-capabilities: [* capability], } 7.3. SESSION_RESUME Payload session-resume = { old-session-id: uint .size 2, ticket: bstr .size 64, } ; Ticket structure (encrypted with server key, AES-256-GCM): ; - session-key: 32 bytes ; - device-id: 16 bytes ; - issued-at: 4 bytes (Unix timestamp) ; - expires-at: 4 bytes (Unix timestamp) ; - ticket-nonce: 8 bytes 8. Tier Compatibility When endpoints support different maximum tiers, they MUST negotiate to the highest common tier. The server MUST respond with the minimum of its supported tier and the client's requested tier. Servers MAY enforce minimum tier requirements for specific operations. If a client requests an operation at an insufficient tier, the server MUST respond with error code 0x12 (FORBIDDEN) and include the required tier in the error payload. 8.1. Minimum Tier Requirements The following operations have minimum tier requirements: Arcan Expires 14 July 2026 [Page 21] Internet-Draft MyClerk Protocol January 2026 +===============================+==============+ | Operation Category | Minimum Tier | +===============================+==============+ | Lock/Unlock (physical access) | 3 | +-------------------------------+--------------+ | Key Exchange | 4 | +-------------------------------+--------------+ | Federation Operations | 4 | +-------------------------------+--------------+ | Emergency Operations | 3 | +-------------------------------+--------------+ Table 16: Minimum Tier Requirements 9. Error Handling Error codes are 8-bit values organized into ranges: +===========+===================+ | Range | Category | +===========+===================+ | 0x00-0x0F | Success | +-----------+-------------------+ | 0x10-0x1F | Client Errors | +-----------+-------------------+ | 0x20-0x2F | Server Errors | +-----------+-------------------+ | 0x30-0x3F | Federation Errors | +-----------+-------------------+ | 0xF0-0xFF | Reserved | +-----------+-------------------+ Table 17: Error Codes 9.1. Specific Error Codes 0x00 OK Operation completed successfully. 0x10 BAD_REQUEST Malformed message or invalid parameters. 0x11 UNAUTHORIZED Authentication required or failed. 0x12 FORBIDDEN Insufficient permissions or tier. 0x13 NOT_FOUND Requested resource does not exist. 0x17 INVALID_SESSION Session expired or invalid. Arcan Expires 14 July 2026 [Page 22] Internet-Draft MyClerk Protocol January 2026 0x20 INTERNAL_ERROR Server encountered an unexpected error. 0x21 SERVICE_UNAVAILABLE Service temporarily unavailable. 0x22 TIMEOUT Operation timed out. 10. Security Considerations 10.1. Nonce Reuse Reusing a nonce with the same key in ChaCha20-Poly1305 completely compromises the confidentiality and authenticity of all messages encrypted with that key-nonce pair. Implementations MUST ensure nonces are never reused by: * Using cryptographically random values for the Random field * Maintaining a monotonic counter per session * Rotating keys before counter exhaustion 10.2. Replay Protection Tier 3+ messages include timestamps for replay protection. Implementations SHOULD reject messages with timestamps more than 5 minutes in the past or future. Session resumption tickets include a nonce that MUST be tracked to prevent replay attacks. 10.3. Tier Downgrade Attacks An attacker might attempt to force communication at a lower tier. Servers MUST enforce minimum tier requirements for sensitive operations. Clients SHOULD warn users when connecting at a lower tier than expected. 10.4. Key Compromise If a session key is compromised, an attacker can decrypt all messages in that session. The 24-hour automatic key rotation limits the window of exposure. For forward secrecy, implementations SHOULD use ephemeral ECDH keys for each session. 10.5. Post-Quantum Considerations The X25519 key exchange is not quantum-resistant. Tier 5 includes an additional HMAC-SHA256 trailer that provides some protection against future quantum attacks on Poly1305. Implementations concerned about long-term confidentiality SHOULD use Tier 5 for sensitive data. Arcan Expires 14 July 2026 [Page 23] Internet-Draft MyClerk Protocol January 2026 11. IANA Considerations This document has no IANA actions. If this protocol were to be standardized, IANA would be requested to create a registry for MyClerk Protocol operation codes with the ranges defined in Section 6. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8439] Nir, Y. and A. Langley, "ChaCha20 and Poly1305 for IETF Protocols", RFC 8439, DOI 10.17487/RFC8439, June 2018, . [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, . [RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves for Security", RFC 7748, DOI 10.17487/RFC7748, January 2016, . [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, June 2019, . [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, December 2020, . Arcan Expires 14 July 2026 [Page 24] Internet-Draft MyClerk Protocol January 2026 Acknowledgements This specification is part of the MyClerk project, a privacy-first family orchestration platform currently in development. For more information, visit https://myclerk.eu. Author's Address Michael J. Arcan Arcan Consulting Email: rfc@arcan-consulting.de URI: https://myclerk.eu Arcan Expires 14 July 2026 [Page 25]