The MyClerk Protocol: Tiered Security Communication for Distributed Family Systems
draft-myclerk-protocol-02
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| Document | Type | Active Internet-Draft (individual) | |
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| Author | Michael J. Arcan | ||
| Last updated | 2026-01-30 | ||
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draft-myclerk-protocol-02
Independent Submission M.J. ArcanInternet-Draft Arcan ConsultingIntended status: Experimental 29 January 2026Expires: 2 August 2026 The MyClerk Protocol: Tiered Security Communication for Distributed Family Systems draft-myclerk-protocol-02Abstract 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 2 August 2026.Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.Arcan Expires 2 August 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 . . . . . . . . . . . . . . . . . . . . . . . 4 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Design Goals . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Default Port . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Security Tiers Overview . . . . . . . . . . . . . . . . . 5 3. Message Format . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Common Header Fields . . . . . . . . . . . . . . . . . . 5 3.2. Tier 0 Header (1 byte) . . . . . . . . . . . . . . . . . 6 3.3. Tier 1 Header (4 bytes) . . . . . . . . . . . . . . . . . 6 3.4. Tier 2 Header (6 bytes) . . . . . . . . . . . . . . . . . 6 3.5. Tier 3 Header (12 bytes) . . . . . . . . . . . . . . . . 7 3.6. Tier 4 Header (42 bytes) . . . . . . . . . . . . . . . . 7 3.7. Tier 5 Header (58 bytes) . . . . . . . . . . . . . . . . 8 4. Nonce Construction . . . . . . . . . . . . . . . . . . . . . 8 5. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. ECDH Key Exchange . . . . . . . . . . . . . . . . . . . . 9 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) . . . . . . . 13 6.2.4. Dynamic Routing and ACL (0x0240-0x024F) . . . . . . . 13 6.2.5. Client Assignment Operations (0x0250-0x025F) . . . . 14 6.3. Hardware Passthrough Operations (0x0600-0x06FF) . . . . . 16 6.3.1. USB Operations (0x0600-0x060F) . . . . . . . . . . . 16 6.3.2. Serial Operations (0x0610-0x061F) . . . . . . . . . . 17 6.3.3. GPIO Operations (0x0620-0x062F) . . . . . . . . . . . 18 6.3.4. I2C Operations (0x0630-0x063F) . . . . . . . . . . . 19 6.3.5. SPI Operations (0x0640-0x064F) . . . . . . . . . . . 20 6.3.6. CAN Bus Operations (0x0650-0x065F) . . . . . . . . . 21 6.3.7. 1-Wire Operations (0x0660-0x066F) . . . . . . . . . . 21 6.3.8. GSM Modem Operations (0x0670-0x067F) . . . . . . . . 22 6.4. Vendor Extension: SMS Gateway (0xF350-0xF37F) . . . . . . 24 6.4.1. SMS Gateway Operations (0xF350-0xF35F) . . . . . . . 24Arcan Expires 2 August 2026 [Page 2]Internet-Draft MyClerk Protocol January 2026 6.4.2. SMS Parsing Operations (0xF360-0xF36F) . . . . . . . 24 6.4.3. Emergency Gateway Operations (0xF370-0xF37F) . . . . 25 7. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 26 7.1. SESSION_INIT Payload . . . . . . . . . . . . . . . . . . 26 7.2. SESSION_ACK Payload . . . . . . . . . . . . . . . . . . . 27 7.3. SESSION_RESUME Payload . . . . . . . . . . . . . . . . . 27 8. Tier Compatibility . . . . . . . . . . . . . . . . . . . . . 27 8.1. Minimum Tier Requirements . . . . . . . . . . . . . . . . 28 9. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 28 9.1. Specific Error Codes . . . . . . . . . . . . . . . . . . 28 10. Security Considerations . . . . . . . . . . . . . . . . . . . 29 10.1. Nonce Reuse . . . . . . . . . . . . . . . . . . . . . . 29 10.2. Replay Protection . . . . . . . . . . . . . . . . . . . 29 10.3. Tier Downgrade Attacks . . . . . . . . . . . . . . . . . 29 10.4. Key Compromise . . . . . . . . . . . . . . . . . . . . . 30 10.5. Post-Quantum Considerations . . . . . . . . . . . . . . 30 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 11.1. Service Name and Port Number Registration . . . . . . . 30 11.2. Operation Code Registry . . . . . . . . . . . . . . . . 30 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 12.1. Normative References . . . . . . . . . . . . . . . . . . 31 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 32 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 321. 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.Arcan Expires 2 August 2026 [Page 3]Internet-Draft MyClerk Protocol January 20261.2. 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. 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. Default Port When using TCP or UDP as the transport protocol, implementations SHOULD use port 5657 as the default listening port. This port is registered with IANA for the "myclerk" service (see Section 11.1).Arcan Expires 2 August 2026 [Page 4]Internet-Draft MyClerk Protocol January 2026 Implementations MAY use alternative ports when: * Operating behind a reverse proxy or load balancer * Running multiple instances on the same host * Required by local network policies Service discovery mechanisms (such as mDNS or DNS-SD) SHOULD advertise the actual port in use, regardless of whether it matches the default.2.3. 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 | | | | +----+------+-------------------+----------------+-----------------+ |4 |42 | ChaCha20-Poly1305 | HMAC-64 | Key exchange | | |bytes | | | | +----+------+-------------------+----------------+-----------------+ |5 |58+ | ChaCha20-Poly1305 | HMAC-256 + | Maximum | | |bytes | | Poly1305 | security | +----+------+-------------------+----------------+-----------------+ Table 1: Security Tier Summary3. 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:Arcan Expires 2 August 2026 [Page 5]Internet-Draft MyClerk Protocol January 2026 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 encrypted3.2. 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.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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Arcan Expires 2 August 2026 [Page 6]Internet-Draft MyClerk Protocol January 2026 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].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 inArcan Expires 2 August 2026 [Page 7]Internet-Draft MyClerk Protocol January 2026 [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.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.Arcan Expires 2 August 2026 [Page 8]Internet-Draft MyClerk Protocol January 2026 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 )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 2 August 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 Ranges6.1. 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 2 August 2026 [Page 10]Internet-Draft MyClerk Protocol January 2026 +--------+-------------------+----------------------------+ | 0x0008 | SESSION_RESUMED | Session resumed | +--------+-------------------+----------------------------+ Table 3: Session Management Operations6.1.2. 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 Operations6.2. 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 2 August 2026 [Page 11]Internet-Draft MyClerk Protocol January 2026 +--------+---------------------+-------------------------------+ | 0x0207 | DEVICE_CAPABILITIES | Query device capabilities | +--------+---------------------+-------------------------------+ | 0x020B | DEVICE_DISCOVER | List all connected devices | | | | (including unshared) | +--------+---------------------+-------------------------------+ Table 5: Device Management Operations DEVICE_LIST (0x0200) returns only devices currently being shared. DEVICE_DISCOVER (0x020B) returns all connected devices regardless of sharing status, enabling provisioning workflows.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)Arcan Expires 2 August 2026 [Page 12]Internet-Draft MyClerk Protocol January 20266.2.3. GPU Service Operations (0x0220-0x022F) GPU operations enable queue-based access to inference services (LLM, TTS, STT, Image Generation). +========+================+==========================+ | 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 2 August 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)6.2.5. Client Assignment Operations (0x0250-0x025F) Client Assignment operations enable Hub-managed device provisioning. A Hub can assign devices to clients, and servers can request approval for sharing new devices through a token-based workflow.Arcan Expires 2 August 2026 [Page 14]Internet-Draft MyClerk Protocol January 2026 +========+========================+===============================+ | Code | Name | Description | +========+========================+===============================+ | 0x0250 | CLIENT_REGISTER | Register client with server | +--------+------------------------+-------------------------------+ | 0x0251 | CLIENT_HEARTBEAT | Client keepalive | +--------+------------------------+-------------------------------+ | 0x0252 | CLIENT_ASSIGN | Assign device to client | +--------+------------------------+-------------------------------+ | 0x0253 | CLIENT_REVOKE | Revoke device from client | +--------+------------------------+-------------------------------+ | 0x0254 | CLIENT_STATUS | Query client status | +--------+------------------------+-------------------------------+ | 0x0255 | CLIENT_LIST | List registered clients | +--------+------------------------+-------------------------------+ | 0x0256 | CLIENT_INFO | Get client information | +--------+------------------------+-------------------------------+ | 0x0257 | DEVICE_REQUEST_CREATE | Create device sharing request | +--------+------------------------+-------------------------------+ | 0x0258 | DEVICE_REQUEST_LIST | List pending device requests | +--------+------------------------+-------------------------------+ | 0x0259 | DEVICE_REQUEST_DETAILS | Get request details | +--------+------------------------+-------------------------------+ | 0x025A | DEVICE_REQUEST_RESPOND | Approve/reject device request | +--------+------------------------+-------------------------------+ | 0x025B | DEVICE_REQUEST_CANCEL | Cancel pending request | +--------+------------------------+-------------------------------+ Table 9: Client Assignment Operations Device Request Workflow: 1. Hub queries server with DEVICE_DISCOVER (0x020B) to list available devices 2. Hub administrator creates request via DEVICE_REQUEST_CREATE (0x0257) 3. Server queries pending requests via DEVICE_REQUEST_LIST (0x0258) 4. Server retrieves details via DEVICE_REQUEST_DETAILS (0x0259) 5. Server administrator approves/rejects via DEVICE_REQUEST_RESPOND (0x025A) Request states: * 0x00: Pending (awaiting server approval)Arcan Expires 2 August 2026 [Page 15]Internet-Draft MyClerk Protocol January 2026 * 0x01: Approved (all devices accepted) * 0x02: Partially Approved (subset of devices accepted) * 0x03: Rejected (request denied) * 0x04: Expired (token timeout) * 0x05: Cancelled (hub cancelled request)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 2 August 2026 [Page 16]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 10: USB Operations6.3.2. Serial Operations (0x0610-0x061F) Serial passthrough supports RS-232, RS-485, and UART interfaces.Arcan Expires 2 August 2026 [Page 17]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 11: Serial Operations6.3.3. GPIO Operations (0x0620-0x062F) GPIO operations enable control of General Purpose Input/Output pins.Arcan Expires 2 August 2026 [Page 18]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 12: GPIO Operations6.3.4. I2C Operations (0x0630-0x063F) I2C (Inter-Integrated Circuit) bus operations for sensor and peripheral communication.Arcan Expires 2 August 2026 [Page 19]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 13: I2C Operations6.3.5. 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 14: SPI OperationsArcan Expires 2 August 2026 [Page 20]Internet-Draft MyClerk Protocol January 20266.3.6. 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 15: CAN Bus Operations6.3.7. 1-Wire Operations (0x0660-0x066F) 1-Wire bus operations for temperature sensors, iButtons, and similar devices.Arcan Expires 2 August 2026 [Page 21]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 16: 1-Wire Operations6.3.8. GSM Modem Operations (0x0670-0x067F) GSM modem operations provide direct access to cellular modems for SMS, GNSS (GPS), voice calls, and USSD services. These operations abstract the underlying AT command interface.Arcan Expires 2 August 2026 [Page 22]Internet-Draft MyClerk Protocol January 2026 +========+====================+=============================+ | Code | Name | Description | +========+====================+=============================+ | 0x0670 | GSM_MODEM_INIT | Initialize GSM modem | +--------+--------------------+-----------------------------+ | 0x0671 | GSM_MODEM_STATUS | Get modem status | +--------+--------------------+-----------------------------+ | 0x0672 | GSM_NETWORK_REG | Network registration status | +--------+--------------------+-----------------------------+ | 0x0673 | GSM_SIGNAL_QUALITY | Signal quality (RSSI, BER) | +--------+--------------------+-----------------------------+ | 0x0674 | GSM_SMS_SEND | Send SMS via AT commands | +--------+--------------------+-----------------------------+ | 0x0675 | GSM_SMS_RECEIVE | Receive SMS notification | +--------+--------------------+-----------------------------+ | 0x0676 | GSM_SMS_LIST | List SMS messages | +--------+--------------------+-----------------------------+ | 0x0677 | GSM_SMS_DELETE | Delete SMS from SIM | +--------+--------------------+-----------------------------+ | 0x0678 | GSM_USSD_SEND | Send USSD command | +--------+--------------------+-----------------------------+ | 0x0679 | GSM_USSD_RESPONSE | USSD response | +--------+--------------------+-----------------------------+ | 0x067A | GSM_GNSS_ENABLE | Enable/disable GNSS module | +--------+--------------------+-----------------------------+ | 0x067B | GSM_GNSS_POSITION | Get GNSS position fix | +--------+--------------------+-----------------------------+ | 0x067C | GSM_GNSS_CONFIG | Configure GNSS | +--------+--------------------+-----------------------------+ | 0x067D | GSM_VOICE_DIAL | Initiate voice call | +--------+--------------------+-----------------------------+ | 0x067E | GSM_VOICE_HANGUP | Hangup voice call | +--------+--------------------+-----------------------------+ | 0x067F | GSM_VOICE_ANSWER | Answer incoming call | +--------+--------------------+-----------------------------+ Table 17: GSM Modem Operations GSM modem types supported: * SIM7600: 4G LTE Cat-4 with GNSS * SIM800: 2G GSM/GPRS * Quectel EC25: 4G LTEArcan Expires 2 August 2026 [Page 23]Internet-Draft MyClerk Protocol January 20266.4. Vendor Extension: SMS Gateway (0xF350-0xF37F) The SMS Gateway vendor extension provides application-level SMS handling for the MyClerk platform. Unlike the low-level GSM Modem operations which deal with AT commands and hardware, these operations provide intelligent message routing, TAN/OTP detection, and emergency fallback services.6.4.1. SMS Gateway Operations (0xF350-0xF35F) +========+====================+===============================+ | Code | Name | Description | +========+====================+===============================+ | 0xF350 | SMS_CREATE | Create outgoing SMS | +--------+--------------------+-------------------------------+ | 0xF351 | SMS_SEND | Send SMS via gateway | +--------+--------------------+-------------------------------+ | 0xF352 | SMS_RECEIVE | Incoming SMS notification | +--------+--------------------+-------------------------------+ | 0xF353 | SMS_STATUS | Query message delivery status | +--------+--------------------+-------------------------------+ | 0xF354 | SMS_LIST | List messages in gateway | +--------+--------------------+-------------------------------+ | 0xF355 | SMS_DELETE | Delete message from gateway | +--------+--------------------+-------------------------------+ | 0xF356 | SMS_ROUTE_ADD | Add routing rule | +--------+--------------------+-------------------------------+ | 0xF357 | SMS_ROUTE_REMOVE | Remove routing rule | +--------+--------------------+-------------------------------+ | 0xF358 | SMS_ROUTE_LIST | List routing rules | +--------+--------------------+-------------------------------+ | 0xF359 | SMS_GATEWAY_STATUS | Gateway health status | +--------+--------------------+-------------------------------+ Table 18: SMS Gateway Operations6.4.2. SMS Parsing Operations (0xF360-0xF36F) SMS Parsing operations handle intelligent classification and extraction of structured data from SMS messages.Arcan Expires 2 August 2026 [Page 24]Internet-Draft MyClerk Protocol January 2026 +========+==========================+=============================+ | Code | Name | Description | +========+==========================+=============================+ | 0xF360 | SMS_PARSED | Parsed SMS event | +--------+--------------------------+-----------------------------+ | 0xF361 | SMS_CLASSIFY | Classify SMS type | +--------+--------------------------+-----------------------------+ | 0xF362 | SMS_TAN_RECEIVED | TAN/OTP received event | +--------+--------------------------+-----------------------------+ | 0xF363 | SMS_TAN_ANNOUNCE | Announce TAN to family | +--------+--------------------------+-----------------------------+ | 0xF364 | SMS_TAN_CLAIM | Claim TAN ownership | +--------+--------------------------+-----------------------------+ | 0xF365 | SMS_TAN_EXPIRE | TAN expiration notification | +--------+--------------------------+-----------------------------+ | 0xF366 | SMS_DELIVERY_RECEIVED | Delivery notification | | | | received | +--------+--------------------------+-----------------------------+ | 0xF367 | SMS_APPOINTMENT_RECEIVED | Appointment SMS received | +--------+--------------------------+-----------------------------+ | 0xF368 | SMS_SPAM_DETECTED | Spam SMS detected | +--------+--------------------------+-----------------------------+ | 0xF369 | SMS_ALERT_RECEIVED | Alert/warning SMS received | +--------+--------------------------+-----------------------------+ Table 19: SMS Parsing Operations SMS classification types: * 0x01: TAN/OTP (banking, 2FA codes) * 0x02: Delivery notification (package tracking) * 0x03: Appointment reminder * 0x04: Marketing/Spam * 0x05: Alert/Warning (weather, emergency) * 0x06: Personal message * 0x07: Unknown6.4.3. Emergency Gateway Operations (0xF370-0xF37F) Emergency Gateway operations provide fallback communication when primary channels (internet, Matrix) are unavailable. The SMS gateway automatically activates emergency mode during outages.Arcan Expires 2 August 2026 [Page 25]Internet-Draft MyClerk Protocol January 2026 +========+=============================+===========================+ | Code | Name | Description | +========+=============================+===========================+ | 0xF370 | EMERGENCY_GATEWAY_STATUS | Gateway health status | +--------+-----------------------------+---------------------------+ | 0xF371 | EMERGENCY_INTERNET_DOWN | Internet outage detected | +--------+-----------------------------+---------------------------+ | 0xF372 | EMERGENCY_INTERNET_UP | Internet restored | +--------+-----------------------------+---------------------------+ | 0xF373 | EMERGENCY_SMS_ALERT | Emergency alert via SMS | +--------+-----------------------------+---------------------------+ | 0xF374 | EMERGENCY_SMS_COMMAND | Emergency command via SMS | +--------+-----------------------------+---------------------------+ | 0xF375 | EMERGENCY_LOCATION_REQUEST | Request device location | +--------+-----------------------------+---------------------------+ | 0xF376 | EMERGENCY_LOCATION_RESPONSE | Device location response | +--------+-----------------------------+---------------------------+ | 0xF377 | EMERGENCY_HEALTH_CHECK | Remote health check | | | | request | +--------+-----------------------------+---------------------------+ | 0xF378 | EMERGENCY_HEALTH_RESPONSE | Health check response | +--------+-----------------------------+---------------------------+ | 0xF379 | EMERGENCY_MODE_ACTIVATE | Activate emergency mode | +--------+-----------------------------+---------------------------+ | 0xF37A | EMERGENCY_MODE_DEACTIVATE | Deactivate emergency mode | +--------+-----------------------------+---------------------------+ Table 20: Emergency Gateway Operations Emergency mode features: * Automatic activation when internet connectivity is lost * Predefined SMS commands for remote device control * Location sharing via GNSS coordinates in SMS * Health monitoring with battery and connectivity status * Graceful transition back to normal operation7. Payload Formats Payloads are encoded using MessagePack (a subset of CBOR). This section defines payload structures using CDDL [RFC8610].7.1. SESSION_INIT PayloadArcan Expires 2 August 2026 [Page 26]Internet-Draft MyClerk Protocol January 2026 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, )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 bytes8. 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.Arcan Expires 2 August 2026 [Page 27]Internet-Draft MyClerk Protocol January 2026 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: +===============================+==============+ | Operation Category | Minimum Tier | +===============================+==============+ | Lock/Unlock (physical access) | 3 | +-------------------------------+--------------+ | Key Exchange | 4 | +-------------------------------+--------------+ | Federation Operations | 4 | +-------------------------------+--------------+ | Emergency Operations | 3 | +-------------------------------+--------------+ Table 21: Minimum Tier Requirements9. 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 22: Error Codes9.1. Specific Error Codes 0x00 OK Operation completed successfully. 0x10 BAD_REQUEST Malformed message or invalid parameters.Arcan Expires 2 August 2026 [Page 28]Internet-Draft MyClerk Protocol January 2026 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. 0x20 INTERNAL_ERROR Server encountered an unexpected error. 0x21 SERVICE_UNAVAILABLE Service temporarily unavailable. 0x22 TIMEOUT Operation timed out.10. Security Considerations10.1. 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 exhaustion10.2. 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.Arcan Expires 2 August 2026 [Page 29]Internet-Draft MyClerk Protocol January 202610.4. 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.11. IANA Considerations11.1. Service Name and Port Number Registration IANA is requested to register the following service name and port number in the "Service Name and Transport Protocol Port Number Registry" [RFC6335]: Service Name: myclerk Port Number: 5657 Transport Protocol(s): TCP, UDP Description: MyClerk Protocol Assignee: IESG <iesg@ietf.org> Contact: IETF Chair <chair@ietf.org> Reference: This document TCP is the primary transport for control messages, synchronization, authentication, and VFS operations. UDP is used for real-time streaming (video, audio) and low-latency sensor telemetry where latency is prioritized over reliability.11.2. Operation Code Registry IANA is requested to create a new registry titled "MyClerk Protocol Operation Codes" with the following structure: Registration Procedure: Expert Review per [RFC8126]Arcan Expires 2 August 2026 [Page 30]Internet-Draft MyClerk Protocol January 2026 Reference: This document The initial entries are the operation codes defined in Section 6 of this document, organized into the following ranges: +===============+======================+===================+ | Range | Category | Reference | +===============+======================+===================+ | 0x0001-0x00FF | Core Operations | Section 4 | +---------------+----------------------+-------------------+ | 0x0100-0x01FF | File Operations | Section 5 | +---------------+----------------------+-------------------+ | 0x0200-0x02FF | Calendar Operations | Section 5 | +---------------+----------------------+-------------------+ | 0x0300-0x03FF | Contact Operations | Section 5 | +---------------+----------------------+-------------------+ | 0x0400-0x04FF | Task Operations | Section 5 | +---------------+----------------------+-------------------+ | 0x0450-0x049F | Resource Sharing | Section 6 | +---------------+----------------------+-------------------+ | 0x0500-0x05FF | VFS Operations | draft-myclerk-vfs | +---------------+----------------------+-------------------+ | 0x0600-0x06FF | Hardware Passthrough | Section 6 | +---------------+----------------------+-------------------+ | 0x1000-0x10FF | Presence Operations | Section 5 | +---------------+----------------------+-------------------+ | 0xF000-0xFFFF | Private/Experimental | This document | +---------------+----------------------+-------------------+ Table 2312. References12.1. 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, <https://www.rfc-editor.org/info/rfc2119>. [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, <https://www.rfc-editor.org/info/rfc5869>. [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name andArcan Expires 2 August 2026 [Page 31]Internet-Draft MyClerk Protocol January 2026 Transport Protocol Port Number Registry", BCP 165, RFC 6335, DOI 10.17487/RFC6335, August 2011, <https://www.rfc-editor.org/info/rfc6335>. [RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves for Security", RFC 7748, DOI 10.17487/RFC7748, January 2016, <https://www.rfc-editor.org/info/rfc7748>. [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, <https://www.rfc-editor.org/info/rfc8126>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8439] Nir, Y. and A. Langley, "ChaCha20 and Poly1305 for IETF Protocols", RFC 8439, DOI 10.17487/RFC8439, June 2018, <https://www.rfc-editor.org/info/rfc8439>. [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, <https://www.rfc-editor.org/info/rfc8610>. [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, December 2020, <https://www.rfc-editor.org/info/rfc8949>.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.euArcan Expires 2 August 2026 [Page 32]