Independent Submission M.J. Arcan Internet-Draft Arcan Consulting Intended status: Experimental 27 April 2026 Expires: 29 October 2026 The MyClerk Protocol: Tiered Security Communication for Distributed Family Systems draft-myclerk-protocol-03 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 AEAD with hybrid post-quantum key establishment combining ML-KEM-768 and X25519. A classical-only mode (X25519 without ML-KEM) remains available for resource-constrained devices and legacy interoperability. 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 29 October 2026. Arcan Expires 29 October 2026 [Page 1] Internet-Draft MyClerk Protocol April 2026 Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. 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 . . . . . . . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Design Goals . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Default Port . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Security Tiers Overview . . . . . . . . . . . . . . . . . 5 3. Message Format . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Common Header Fields . . . . . . . . . . . . . . . . . . 6 3.2. Tier 0 Header (1 byte) . . . . . . . . . . . . . . . . . 6 3.3. Tier 1 Header (4 bytes) . . . . . . . . . . . . . . . . . 7 3.4. Tier 2 Header (6 bytes) . . . . . . . . . . . . . . . . . 7 3.5. Tier 3 Header (12 bytes) . . . . . . . . . . . . . . . . 7 3.6. Tier 4 Header (14 bytes) . . . . . . . . . . . . . . . . 8 3.7. Tier 5 Header (14 bytes + Poly1305 Tag) . . . . . . . . . 8 3.8. Request Correlation (Version 1) . . . . . . . . . . . . . 9 3.8.1. Request ID Semantics . . . . . . . . . . . . . . . . 10 3.8.2. Backward Compatibility . . . . . . . . . . . . . . . 10 4. Nonce Construction . . . . . . . . . . . . . . . . . . . . . 11 5. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 11 5.1. Hybrid Key Exchange . . . . . . . . . . . . . . . . . . . 11 5.2. Classical-only Key Exchange (Legacy / Constrained) . . . 13 5.3. Key Rotation . . . . . . . . . . . . . . . . . . . . . . 13 6. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 14 6.1. Core Operations (0x0000-0x00FF) . . . . . . . . . . . . . 15 6.1.1. Session Management (0x0000-0x000F) . . . . . . . . . 16 6.1.2. Key Management (0x0010-0x001F) . . . . . . . . . . . 16 6.2. Standard Operations (0x0100-0x01FF) . . . . . . . . . . . 17 6.2.1. Identity Management (0x0190-0x01EF) . . . . . . . . . 17 6.3. Resource Sharing Operations (0x0200-0x02FF) . . . . . . . 19 6.3.1. Device Management (0x0200-0x020F) . . . . . . . . . . 19 6.3.2. Stream Operations (0x0210-0x021F) . . . . . . . . . . 20 6.3.3. GPU Service Operations (0x0220-0x022F) . . . . . . . 21 6.3.4. Dynamic Routing and ACL (0x0240-0x024F) . . . . . . . 21 6.3.5. Client Assignment Operations (0x0250-0x025F) . . . . 22 Arcan Expires 29 October 2026 [Page 2] Internet-Draft MyClerk Protocol April 2026 6.4. Hardware Passthrough Operations (0x0600-0x06FF) . . . . . 24 6.4.1. USB Operations (0x0600-0x060F) . . . . . . . . . . . 24 6.4.2. Serial Operations (0x0610-0x061F) . . . . . . . . . . 25 6.4.3. GPIO Operations (0x0620-0x062F) . . . . . . . . . . . 26 6.4.4. I2C Operations (0x0630-0x063F) . . . . . . . . . . . 27 6.4.5. SPI Operations (0x0640-0x064F) . . . . . . . . . . . 28 6.4.6. CAN Bus Operations (0x0650-0x065F) . . . . . . . . . 29 6.4.7. 1-Wire Operations (0x0660-0x066F) . . . . . . . . . . 29 6.4.8. GSM Modem Operations (0x0670-0x067F) . . . . . . . . 30 6.5. Telephony: SMS Gateway (0x0B50-0x0B7F) . . . . . . . . . 32 6.5.1. SMS Gateway Operations (0x0B50-0x0B5F) . . . . . . . 32 6.5.2. SMS Parsing Operations (0x0B60-0x0B6F) . . . . . . . 32 6.5.3. Emergency Gateway Operations (0x0B70-0x0B7F) . . . . 33 6.6. Application Operations (0x0700-0x1DFF) . . . . . . . . . 35 7. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 35 7.1. SESSION_INIT Payload . . . . . . . . . . . . . . . . . . 35 7.2. SESSION_ACK Payload . . . . . . . . . . . . . . . . . . . 36 7.3. SESSION_RESUME Payload . . . . . . . . . . . . . . . . . 37 8. Tier Compatibility . . . . . . . . . . . . . . . . . . . . . 37 8.1. Minimum Tier Requirements . . . . . . . . . . . . . . . . 37 9. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 37 9.1. Specific Error Codes . . . . . . . . . . . . . . . . . . 38 10. Security Considerations . . . . . . . . . . . . . . . . . . . 38 10.1. Nonce Reuse . . . . . . . . . . . . . . . . . . . . . . 38 10.2. Replay Protection . . . . . . . . . . . . . . . . . . . 39 10.3. Tier Downgrade Attacks . . . . . . . . . . . . . . . . . 39 10.4. Key Compromise . . . . . . . . . . . . . . . . . . . . . 39 10.5. Post-Quantum Considerations . . . . . . . . . . . . . . 39 10.6. KEX Mode Downgrade Protection . . . . . . . . . . . . . 40 10.7. ML-KEM Implementation Hazards . . . . . . . . . . . . . 40 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 11.1. Service Name and Port Number Registration . . . . . . . 41 11.2. Operation Code Registry . . . . . . . . . . . . . . . . 42 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 44 12.1. Normative References . . . . . . . . . . . . . . . . . . 44 12.2. Informative References . . . . . . . . . . . . . . . . . 45 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 45 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 45 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. Arcan Expires 29 October 2026 [Page 3] Internet-Draft MyClerk Protocol April 2026 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. 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. Arcan Expires 29 October 2026 [Page 4] Internet-Draft MyClerk Protocol April 2026 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. 5. *Post-Quantum Security:* Default key establishment for Tier 4 and Tier 5 is resistant to attacks by cryptographically relevant quantum computers (CRQCs), using a hybrid of ML-KEM-768 [FIPS203] and X25519 [RFC7748], while retaining a classical-only mode for resource-constrained devices. 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). 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 |Auth |KEX | Use Case | +====+======+===================+========+======+=================+ |0 |1 B | None (tunneled) |None |-- | Inside session | +----+------+-------------------+--------+------+-----------------+ |1 |4 B | None |None |-- | Fire-and-forget | +----+------+-------------------+--------+------+-----------------+ |2 |6 B | Optional |CRC-16 |-- | Home automation | +----+------+-------------------+--------+------+-----------------+ |3 |12 B | ChaCha20-Poly1305 |HMAC-32 |from | Conversational | | | | | |T4/T5 | | +----+------+-------------------+--------+------+-----------------+ |4 |14 B | ChaCha20-Poly1305 |HMAC-64 |hybrid| Key exchange | +----+------+-------------------+--------+------+-----------------+ Arcan Expires 29 October 2026 [Page 5] Internet-Draft MyClerk Protocol April 2026 |5 |14 | ChaCha20-Poly1305 |HMAC-256|hybrid| Max security | | |B+tag | | | | | +----+------+-------------------+--------+------+-----------------+ Table 1: Security Tier Summary KEX abbreviations: "hybrid" denotes ML-KEM-768 + X25519 hybrid key establishment; "from T4/T5" indicates the session key is derived in a separate Tier 4 or Tier 5 handshake and inherited by subsequent Tier 3 traffic. 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|S|E| +-+-+-+-+-+-+-+-+ V: Protocol Version (2 bits) - 0 or 1 T: Security Tier (3 bits) - Values 0-5 C: Compressed (1 bit) - Payload is compressed S: Stream (1 bit) - Server-push stream message 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|S|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 29 October 2026 [Page 6] Internet-Draft MyClerk Protocol April 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|S|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|S|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|S|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 29 October 2026 [Page 7] Internet-Draft MyClerk Protocol April 2026 3.6. Tier 4 Header (14 bytes) Tier 4 carries the messages that establish a session (SESSION_INIT, SESSION_ACK). Earlier drafts of this document carried the 32-byte X25519 ECDH public key inline in a 42-byte header. With the move to a hybrid post-quantum KEX the key material grew to 1184 bytes (ML- KEM-768 encapsulation key) plus 1088 bytes (ML-KEM-768 ciphertext) plus the existing 32 bytes of X25519 per direction, which no longer fits in any sensibly-sized fixed header. Consequently, Tier 4 headers no longer carry KEX material inline; all public keys and ciphertexts are transported in the SESSION_INIT / SESSION_ACK payloads (see Section 7.1), and the header retains only session and nonce identifiers. 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|S|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp (cont.) | Nonce | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Key ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Key ID (32 bits) Identifier for the session key being used or negotiated. Zero during the initial SESSION_INIT before a key has been established. 3.7. Tier 5 Header (14 bytes + Poly1305 Tag) Tier 5 uses the same 14-byte header as Tier 4 but appends a full Poly1305 authentication tag after the header (before the payload): 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 - 14 bytes] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Poly1305 Tag (16 bytes) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Arcan Expires 29 October 2026 [Page 8] Internet-Draft MyClerk Protocol April 2026 Prior drafts of this document mandated an additional HMAC-SHA256 trailer on Tier 5 as a post-quantum resilience workaround against potential future quantum attacks on Poly1305. With hybrid ML-KEM-768 key establishment now baked into Tier 4/5 (see Section 5), that trailer is redundant and has been removed. Implementations conforming to this draft MUST NOT emit an HMAC-SHA256 trailer on Tier 5 messages. 3.8. Request Correlation (Version 1) Version 0 of the protocol correlates responses to requests by Operation Code. This limits each connection to one outstanding request per Operation Code, preventing parallel requests for the same operation (e.g., multiple concurrent thumbnail fetches). Version 1 extends each tier-specific header with a 32-bit Request ID field, inserted after the tier-specific fields and before the payload. The Version field in the Flags byte (bits 0-1) distinguishes V0 from V1. Example: Tier 1 Version 1 Header (8 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1|0 0 1|C|S|E| Operation Code | Sequence | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Request ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header sizes by version: Arcan Expires 29 October 2026 [Page 9] Internet-Draft MyClerk Protocol April 2026 +======+==========+==========+=======+ | Tier | V0 | V1 | Delta | +======+==========+==========+=======+ | 0 | 1 byte | 5 bytes | +4 | +------+----------+----------+-------+ | 1 | 4 bytes | 8 bytes | +4 | +------+----------+----------+-------+ | 2 | 6 bytes | 10 bytes | +4 | +------+----------+----------+-------+ | 3 | 12 bytes | 16 bytes | +4 | +------+----------+----------+-------+ | 4 | 42 bytes | 46 bytes | +4 | +------+----------+----------+-------+ | 5 | 58 bytes | 62 bytes | +4 | +------+----------+----------+-------+ Table 2: Header Sizes: Version 0 vs Version 1 3.8.1. Request ID Semantics Format 32-bit unsigned integer, big-endian byte order. Generation Client-generated, monotonically increasing per connection. Echo The server MUST echo the Request ID from the request in its response. Fire-and-Forget A Request ID of 0x00000000 indicates fire-and- forget; no response correlation is expected. Wrap When the counter reaches 0xFFFFFFFF, it MUST wrap to 0x00000001, skipping zero. 3.8.2. Backward Compatibility Servers MUST support Version 0 and Version 1 simultaneously. The version is determined by bits 0-1 of the Flags byte. A response MUST use the same version as the request that triggered it. Clients that support Version 1 SHOULD set their version bits to 01 and include a Request ID in every request. When communicating with a Version 0 server that ignores the Request ID, the client MUST fall back to Operation Code correlation. Arcan Expires 29 October 2026 [Page 10] Internet-Draft MyClerk Protocol April 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. Hybrid Key Exchange Tier 4+ sessions establish a shared symmetric key using a hybrid construction that combines classical X25519 ECDH [RFC7748] with post- quantum ML-KEM-768 [FIPS203]. The hybrid output is secure as long as at least one of the two primitives remains unbroken: an adversary that eventually breaks X25519 (e.g. by running Shor's algorithm on a cryptographically relevant quantum computer) still has to defeat ML- KEM, and vice versa. Arcan Expires 29 October 2026 [Page 11] Internet-Draft MyClerk Protocol April 2026 ML-KEM-768 (NIST category 3, approximately AES-192-equivalent security) is the default parameter set. ML-KEM-1024 MAY be offered by implementations requiring higher security margin; ML-KEM-512 is NOT RECOMMENDED for new deployments. The initiator generates an ephemeral X25519 key pair and an ephemeral ML-KEM-768 decapsulation key pair, and sends both public keys in SESSION_INIT (see Section 7.1). The responder generates its own ephemeral X25519 key pair, encapsulates against the initiator's ML- KEM encapsulation key to obtain the PQ shared secret and its ciphertext, and returns the X25519 public key together with the ML- KEM ciphertext in SESSION_ACK. Both sides then compute the combined shared secret: ss_classical = X25519(local_x25519_priv, remote_x25519_pub) ; Responder: (ct, ss_pq) = ML-KEM-768.Encapsulate(initiator_mlkem_pub) ; Initiator: ss_pq = ML-KEM-768.Decapsulate(local_mlkem_priv, ct) combined_secret = ss_classical || ss_pq ; 32 + 32 = 64 bytes transcript_hash = SHA-256( SESSION_INIT_bytes || SESSION_ACK_bytes ) session_key = HKDF-SHA256( IKM = combined_secret, salt = nonce_initiator || nonce_responder, info = "myclerk-session-v1-hybrid" || transcript_hash, L = 32 ) The concatenation order ss_classical || ss_pq is fixed and normative. Implementations that swap the order derive a different session key and will fail to communicate; this is a deliberate fail-closed property, not a bug. The transcript_hash folded into the HKDF info parameter binds the session key to the exact bytes of the handshake as observed by the deriving endpoint. An on-path attacker who modifies any handshake field -- stripping a capability, downgrading kex-mode, swapping nonces, altering any declared parameter -- causes the two endpoints to derive different session keys, and the first post-handshake Tier 3 or Tier 5 frame fails its AEAD check. See Section 10.6 for the full security argument. Arcan Expires 29 October 2026 [Page 12] Internet-Draft MyClerk Protocol April 2026 5.2. Classical-only Key Exchange (Legacy / Constrained) Implementations that cannot afford the ~2.3 KB of wire overhead of the hybrid handshake (e.g. ESP32-class devices on low-bandwidth modem links, or legacy clients predating this draft) MAY negotiate classical-only mode by omitting the ML-KEM fields from SESSION_INIT and signalling kex-mode: classical-only. The responder MUST either accept and mirror classical-only in SESSION_ACK, or refuse the session if local policy requires PQ. In classical-only mode the derivation reduces to: combined_secret = X25519(local_x25519_priv, remote_x25519_pub) transcript_hash = SHA-256(SESSION_INIT_bytes || SESSION_ACK_bytes) session_key = HKDF-SHA256( IKM = combined_secret, salt = nonce_initiator || nonce_responder, info = "myclerk-session-v1-classical" || transcript_hash, L = 32 ) The info string intentionally differs between hybrid and classical- only derivations so that a key produced in one mode cannot be mistaken for a key in the other mode -- a domain-separation precaution against cross-protocol attacks. Classical-only sessions MUST NOT be used for data requiring long-term confidentiality (conservatively: more than 10 years), because an attacker who records the traffic today and gains access to a cryptographically relevant quantum computer later can recover the session key. Implementations SHOULD log classical-only negotiations for audit purposes. 5.3. 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: Arcan Expires 29 October 2026 [Page 13] Internet-Draft MyClerk Protocol April 2026 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: +===============+===================================================+ | 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) | +---------------+---------------------------------------------------+ | 0x0700-0x07FF | Knowledge Base | +---------------+---------------------------------------------------+ | 0x0800-0x08FF | Settings & Configuration | +---------------+---------------------------------------------------+ | 0x0900-0x09FF | Room/Channel Management | +---------------+---------------------------------------------------+ | 0x0A00-0x0AFF | Media Handling | +---------------+---------------------------------------------------+ | 0x0B00-0x0BFF | Telephony (Voice, Video, SMS, IVR) | +---------------+---------------------------------------------------+ | 0x0C00-0x0CFF | Calendar & Events | +---------------+---------------------------------------------------+ | 0x0D00-0x0DFF | Tasks, Shopping & Gamification | +---------------+---------------------------------------------------+ | 0x0E00-0x0EFF | Smart Home Devices | +---------------+---------------------------------------------------+ | 0x0F00-0x0FFF | Automation Rules | Arcan Expires 29 October 2026 [Page 14] Internet-Draft MyClerk Protocol April 2026 +---------------+---------------------------------------------------+ | 0x1000-0x10FF | Maya AI Assistant | +---------------+---------------------------------------------------+ | 0x1100-0x11FF | Synchronization & VFS Federation | +---------------+---------------------------------------------------+ | 0x1200-0x12FF | Orchestration (Notifications, Finance) | +---------------+---------------------------------------------------+ | 0x1300-0x13FF | Presence & Status (Education) | +---------------+---------------------------------------------------+ | 0x1400-0x14FF | Health (Social, Community) | +---------------+---------------------------------------------------+ | 0x1500-0x15FF | Location & Mobility | +---------------+---------------------------------------------------+ | 0x1600-0x16FF | Debug, Testing & Plugins | +---------------+---------------------------------------------------+ | 0x1700-0x17FF | Mobile Device Management (MDM) | +---------------+---------------------------------------------------+ | 0x1800-0x18FF | Legal Documents & Care Directives | +---------------+---------------------------------------------------+ | 0x1900-0x19FF | Mobility & Vehicle Management | +---------------+---------------------------------------------------+ | 0x1A00-0x1AFF | Travel & Vacation | +---------------+---------------------------------------------------+ | 0x1B00-0x1BFF | Audit & Compliance | +---------------+---------------------------------------------------+ | 0x1C00-0x1CFF | Audio Pipeline | +---------------+---------------------------------------------------+ | 0x1D00-0x1DFF | Desktop Client | +---------------+---------------------------------------------------+ | 0x1E00-0xEFFF | Unassigned (reserved for future standard | | | categories) | +---------------+---------------------------------------------------+ | 0xF000-0xFFFE | Vendor Extensions (third-party/vendor- | | | specific use only) | +---------------+---------------------------------------------------+ | 0xFFFF | Reserved | +---------------+---------------------------------------------------+ Table 3: Operation Code Ranges 6.1. Core Operations (0x0000-0x00FF) Arcan Expires 29 October 2026 [Page 15] Internet-Draft MyClerk Protocol April 2026 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 | +--------+-------------------+----------------------------+ | 0x0008 | SESSION_RESUMED | Session resumed | +--------+-------------------+----------------------------+ Table 4: 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 5: Key Management Operations Arcan Expires 29 October 2026 [Page 16] Internet-Draft MyClerk Protocol April 2026 6.2. Standard Operations (0x0100-0x01FF) Standard Operations cover authentication, device registration, messaging, and identity management. The 0x0100-0x018F range is defined for authentication, key exchange, sessions, device registration, backup codes, and messaging. The 0x0190-0x01EF range is allocated to identity management operations. 6.2.1. Identity Management (0x0190-0x01EF) Identity Management operations handle user lifecycle, profile management, authentication credentials, and two-factor authentication. All Identity Management operations MUST be sent at Tier 3 (Encrypted) or higher. 6.2.1.1. User Identity (0x0190-0x019F) +========+=============+======================+ | Code | Name | Description | +========+=============+======================+ | 0x0190 | USER_CREATE | Create user account | +--------+-------------+----------------------+ | 0x0191 | USER_GET | Get user information | +--------+-------------+----------------------+ | 0x0192 | USER_UPDATE | Update user account | +--------+-------------+----------------------+ | 0x0193 | USER_DELETE | Delete user account | +--------+-------------+----------------------+ | 0x0194 | USER_LIST | List users | +--------+-------------+----------------------+ | 0x0195 | USER_SEARCH | Search users | +--------+-------------+----------------------+ Table 6: User Identity Operations 6.2.1.2. User Moderation (0x01A0-0x01AF) +========+==============+==============+ | Code | Name | Description | +========+==============+==============+ | 0x01A0 | USER_BLOCK | Block user | +--------+--------------+--------------+ | 0x01A1 | USER_UNBLOCK | Unblock user | +--------+--------------+--------------+ | 0x01A2 | USER_MUTE | Mute user | +--------+--------------+--------------+ | 0x01A3 | USER_UNMUTE | Unmute user | +--------+--------------+--------------+ Arcan Expires 29 October 2026 [Page 17] Internet-Draft MyClerk Protocol April 2026 Table 7: User Moderation Operations 6.2.1.3. Profile and Avatar (0x01B0-0x01BF) +========+================+=====================+ | Code | Name | Description | +========+================+=====================+ | 0x01B0 | PROFILE_GET | Get user profile | +--------+----------------+---------------------+ | 0x01B1 | PROFILE_UPDATE | Update user profile | +--------+----------------+---------------------+ | 0x01B2 | AVATAR_SET | Set user avatar | +--------+----------------+---------------------+ | 0x01B3 | AVATAR_GET | Get user avatar | +--------+----------------+---------------------+ Table 8: Profile and Avatar Operations 6.2.1.4. Preferences (0x01C0-0x01CF) +========+=================+======================+ | Code | Name | Description | +========+=================+======================+ | 0x01C0 | PREFERENCES_GET | Get user preferences | +--------+-----------------+----------------------+ | 0x01C1 | PREFERENCES_SET | Set user preferences | +--------+-----------------+----------------------+ Table 9: Preferences Operations 6.2.1.5. Password and Email (0x01D0-0x01DF) +========+=================+======================+ | Code | Name | Description | +========+=================+======================+ | 0x01D0 | PASSWORD_CHANGE | Change password | +--------+-----------------+----------------------+ | 0x01D1 | PASSWORD_RESET | Reset password | +--------+-----------------+----------------------+ | 0x01D2 | EMAIL_CHANGE | Change email address | +--------+-----------------+----------------------+ | 0x01D3 | EMAIL_VERIFY | Verify email address | +--------+-----------------+----------------------+ Table 10: Password and Email Operations Arcan Expires 29 October 2026 [Page 18] Internet-Draft MyClerk Protocol April 2026 PASSWORD_CHANGE requires the current password in the payload. PASSWORD_RESET initiates an out-of-band reset flow. EMAIL_CHANGE triggers a verification email to the new address; the change is not effective until EMAIL_VERIFY is completed. 6.2.1.6. TOTP Two-Factor Authentication (0x01E0-0x01EF) +========+==============+==========================+ | Code | Name | Description | +========+==============+==========================+ | 0x01E0 | TOTP_ENABLE | Enable TOTP for account | +--------+--------------+--------------------------+ | 0x01E1 | TOTP_DISABLE | Disable TOTP for account | +--------+--------------+--------------------------+ | 0x01E2 | TOTP_VERIFY | Verify TOTP code | +--------+--------------+--------------------------+ Table 11: TOTP Operations TOTP_ENABLE returns a shared secret and provisioning URI compatible with RFC 6238. The client MUST verify the secret by submitting a valid TOTP code via TOTP_VERIFY before the enablement is finalized. TOTP_DISABLE requires a valid TOTP code or backup code for confirmation. 6.3. 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. 6.3.1. 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 | +--------+---------------------+-------------------------------+ Arcan Expires 29 October 2026 [Page 19] Internet-Draft MyClerk Protocol April 2026 | 0x0206 | DEVICE_CONFIGURE | Configure device parameters | +--------+---------------------+-------------------------------+ | 0x0207 | DEVICE_CAPABILITIES | Query device capabilities | +--------+---------------------+-------------------------------+ | 0x020B | DEVICE_DISCOVER | List all connected devices | | | | (including unshared) | +--------+---------------------+-------------------------------+ Table 12: 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. 6.3.2. 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 13: 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 29 October 2026 [Page 20] Internet-Draft MyClerk Protocol April 2026 6.3.3. 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 14: 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) 6.3.4. 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 29 October 2026 [Page 21] Internet-Draft MyClerk Protocol April 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 15: Dynamic Routing Operations Access modes: * 0x00: None (no access) * 0x01: Read-only * 0x02: Write-only * 0x03: Read-write * 0x04: Exclusive (single client) 6.3.5. 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 29 October 2026 [Page 22] Internet-Draft MyClerk Protocol April 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 16: 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 29 October 2026 [Page 23] Internet-Draft MyClerk Protocol April 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) 6.4. 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. 6.4.1. 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 29 October 2026 [Page 24] Internet-Draft MyClerk Protocol April 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 17: USB Operations 6.4.2. Serial Operations (0x0610-0x061F) Serial passthrough supports RS-232, RS-485, and UART interfaces. Arcan Expires 29 October 2026 [Page 25] Internet-Draft MyClerk Protocol April 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 18: Serial Operations 6.4.3. GPIO Operations (0x0620-0x062F) GPIO operations enable control of General Purpose Input/Output pins. Arcan Expires 29 October 2026 [Page 26] Internet-Draft MyClerk Protocol April 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 19: GPIO Operations 6.4.4. I2C Operations (0x0630-0x063F) I2C (Inter-Integrated Circuit) bus operations for sensor and peripheral communication. Arcan Expires 29 October 2026 [Page 27] Internet-Draft MyClerk Protocol April 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 20: I2C Operations 6.4.5. 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 21: SPI Operations Arcan Expires 29 October 2026 [Page 28] Internet-Draft MyClerk Protocol April 2026 6.4.6. 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 22: CAN Bus Operations 6.4.7. 1-Wire Operations (0x0660-0x066F) 1-Wire bus operations for temperature sensors, iButtons, and similar devices. Arcan Expires 29 October 2026 [Page 29] Internet-Draft MyClerk Protocol April 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 23: 1-Wire Operations 6.4.8. 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 29 October 2026 [Page 30] Internet-Draft MyClerk Protocol April 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 24: GSM Modem Operations GSM modem types supported: * SIM7600: 4G LTE Cat-4 with GNSS * SIM800: 2G GSM/GPRS * Quectel EC25: 4G LTE Arcan Expires 29 October 2026 [Page 31] Internet-Draft MyClerk Protocol April 2026 6.5. Telephony: SMS Gateway (0x0B50-0x0B7F) The SMS Gateway operations provide 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. These are standard protocol operations in the Telephony category (0x0B00-0x0BFF). 6.5.1. SMS Gateway Operations (0x0B50-0x0B5F) +========+====================+===============================+ | Code | Name | Description | +========+====================+===============================+ | 0x0B50 | SMS_CREATE | Create outgoing SMS | +--------+--------------------+-------------------------------+ | 0x0B51 | SMS_SEND | Send SMS via gateway | +--------+--------------------+-------------------------------+ | 0x0B52 | SMS_RECEIVE | Incoming SMS notification | +--------+--------------------+-------------------------------+ | 0x0B53 | SMS_STATUS | Query message delivery status | +--------+--------------------+-------------------------------+ | 0x0B54 | SMS_LIST | List messages in gateway | +--------+--------------------+-------------------------------+ | 0x0B55 | SMS_DELETE | Delete message from gateway | +--------+--------------------+-------------------------------+ | 0x0B56 | SMS_ROUTE_ADD | Add routing rule | +--------+--------------------+-------------------------------+ | 0x0B57 | SMS_ROUTE_REMOVE | Remove routing rule | +--------+--------------------+-------------------------------+ | 0x0B58 | SMS_ROUTE_LIST | List routing rules | +--------+--------------------+-------------------------------+ | 0x0B59 | SMS_GATEWAY_STATUS | Gateway health status | +--------+--------------------+-------------------------------+ Table 25: SMS Gateway Operations 6.5.2. SMS Parsing Operations (0x0B60-0x0B6F) SMS Parsing operations handle intelligent classification and extraction of structured data from SMS messages. Arcan Expires 29 October 2026 [Page 32] Internet-Draft MyClerk Protocol April 2026 +========+==========================+=============================+ | Code | Name | Description | +========+==========================+=============================+ | 0x0B60 | SMS_PARSED | Parsed SMS event | +--------+--------------------------+-----------------------------+ | 0x0B61 | SMS_CLASSIFY | Classify SMS type | +--------+--------------------------+-----------------------------+ | 0x0B62 | SMS_TAN_RECEIVED | TAN/OTP received event | +--------+--------------------------+-----------------------------+ | 0x0B63 | SMS_TAN_ANNOUNCE | Announce TAN to family | +--------+--------------------------+-----------------------------+ | 0x0B64 | SMS_TAN_CLAIM | Claim TAN ownership | +--------+--------------------------+-----------------------------+ | 0x0B65 | SMS_TAN_EXPIRE | TAN expiration notification | +--------+--------------------------+-----------------------------+ | 0x0B66 | SMS_DELIVERY_RECEIVED | Delivery notification | | | | received | +--------+--------------------------+-----------------------------+ | 0x0B67 | SMS_APPOINTMENT_RECEIVED | Appointment SMS received | +--------+--------------------------+-----------------------------+ | 0x0B68 | SMS_SPAM_DETECTED | Spam SMS detected | +--------+--------------------------+-----------------------------+ | 0x0B69 | SMS_ALERT_RECEIVED | Alert/warning SMS received | +--------+--------------------------+-----------------------------+ Table 26: 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: Unknown 6.5.3. Emergency Gateway Operations (0x0B70-0x0B7F) Emergency Gateway operations provide fallback communication when primary channels (internet, Matrix) are unavailable. The SMS gateway automatically activates emergency mode during outages. Arcan Expires 29 October 2026 [Page 33] Internet-Draft MyClerk Protocol April 2026 +========+=============================+===========================+ | Code | Name | Description | +========+=============================+===========================+ | 0x0B70 | EMERGENCY_GATEWAY_STATUS | Gateway health status | +--------+-----------------------------+---------------------------+ | 0x0B71 | EMERGENCY_INTERNET_DOWN | Internet outage detected | +--------+-----------------------------+---------------------------+ | 0x0B72 | EMERGENCY_INTERNET_UP | Internet restored | +--------+-----------------------------+---------------------------+ | 0x0B73 | EMERGENCY_SMS_ALERT | Emergency alert via SMS | +--------+-----------------------------+---------------------------+ | 0x0B74 | EMERGENCY_SMS_COMMAND | Emergency command via SMS | +--------+-----------------------------+---------------------------+ | 0x0B75 | EMERGENCY_LOCATION_REQUEST | Request device location | +--------+-----------------------------+---------------------------+ | 0x0B76 | EMERGENCY_LOCATION_RESPONSE | Device location response | +--------+-----------------------------+---------------------------+ | 0x0B77 | EMERGENCY_HEALTH_CHECK | Remote health check | | | | request | +--------+-----------------------------+---------------------------+ | 0x0B78 | EMERGENCY_HEALTH_RESPONSE | Health check response | +--------+-----------------------------+---------------------------+ | 0x0B79 | EMERGENCY_MODE_ACTIVATE | Activate emergency mode | +--------+-----------------------------+---------------------------+ | 0x0B7A | EMERGENCY_MODE_DEACTIVATE | Deactivate emergency mode | +--------+-----------------------------+---------------------------+ Table 27: 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 operation Note: As of the reference implementation, SMS Gateway operations (0xF350-0xF35F), SMS Parsing operations (0xF360-0xF36F), and Emergency Gateway operations (0xF370-0xF37F) have been relocated to the Telephony category (0x0B50-0x0B7F) for consistency. The vendor extension range assignments are retained for backwards compatibility but implementations SHOULD use the Telephony range. Arcan Expires 29 October 2026 [Page 34] Internet-Draft MyClerk Protocol April 2026 6.6. Application Operations (0x0700-0x1DFF) Application-layer operations covering knowledge management, settings, messaging, telephony, calendar, tasks, smart home, automation, AI assistant, synchronization, orchestration, presence, health, location, plugins, MDM, legal documents, mobility, travel, audit, audio pipeline, and desktop client operations are defined in the companion document [MYCLERK-OPS]. The companion document serves as the authoritative registry for all application-layer operation codes in the 0x0700-0x1DFF range, following the "Assigned Numbers" pattern established by Bluetooth SIG specifications. This separation allows the core protocol specification to remain stable while application operations evolve independently. 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 The initiator MUST always include its X25519 public key. It SHOULD additionally include its ML-KEM-768 encapsulation key (and set kex- mode: hybrid-mlkem768) to negotiate the hybrid post-quantum KEX. If the initiator cannot afford the 1184-byte ML-KEM public, it MAY omit mlkem-public and set kex-mode: classical-only; servers that require PQ by policy will refuse such a session. Arcan Expires 29 October 2026 [Page 35] Internet-Draft MyClerk Protocol April 2026 session-init = { nonce: bstr .size 8, timestamp: uint, kex-mode: kex-mode-type, x25519-public: bstr .size 32, ; mlkem-public REQUIRED when kex-mode = hybrid-mlkem768 ? mlkem-public: bstr .size 1184, ? capabilities: [* capability], ? device-id: bstr .size 16, } kex-mode-type = &( classical-only: 0, ; X25519 only (legacy / constrained) hybrid-mlkem768: 1, ; ML-KEM-768 + X25519 (default) ; 2 reserved for future hybrid-mlkem1024 ) capability = &( compression-lz4: 0, compression-zstd: 1, encryption-chacha20: 2, encryption-aes256gcm:3, fragmentation: 4, streaming: 5, federation: 6, vfs: 8, request-correlation: 11, pq-mlkem768: 12, ; signals ML-KEM-768 support ) 7.2. SESSION_ACK Payload The responder MUST echo a selected-kex-mode. When that mode is hybrid-mlkem768, the responder MUST include mlkem-ciphertext: the 1088-byte ML-KEM ciphertext produced by encapsulating against the initiator's encapsulation key. session-ack = { session-id: uint .size 2, nonce: bstr .size 8, selected-tier: uint .le 5, selected-kex-mode: kex-mode-type, x25519-public: bstr .size 32, ; mlkem-ciphertext REQUIRED when ; selected-kex-mode = hybrid-mlkem768 ? mlkem-ciphertext: bstr .size 1088, ? selected-capabilities: [* capability], } Arcan Expires 29 October 2026 [Page 36] Internet-Draft MyClerk Protocol April 2026 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: +===============================+==============+ | Operation Category | Minimum Tier | +===============================+==============+ | Lock/Unlock (physical access) | 3 | +-------------------------------+--------------+ | Key Exchange | 4 | +-------------------------------+--------------+ | Federation Operations | 4 | +-------------------------------+--------------+ | Emergency Operations | 3 | +-------------------------------+--------------+ Table 28: Minimum Tier Requirements 9. Error Handling Error codes are 8-bit values organized into ranges: Arcan Expires 29 October 2026 [Page 37] Internet-Draft MyClerk Protocol April 2026 +===========+===================+ | Range | Category | +===========+===================+ | 0x00-0x0F | Success | +-----------+-------------------+ | 0x10-0x1F | Client Errors | +-----------+-------------------+ | 0x20-0x2F | Server Errors | +-----------+-------------------+ | 0x30-0x3F | Federation Errors | +-----------+-------------------+ | 0xF0-0xFF | Reserved | +-----------+-------------------+ Table 29: 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. 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 Arcan Expires 29 October 2026 [Page 38] Internet-Draft MyClerk Protocol April 2026 * 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 Tier 4 and Tier 5 sessions use hybrid post-quantum key establishment by default, combining ML-KEM-768 [FIPS203] with X25519 [RFC7748] via concatenation and HKDF-SHA256 extraction (see Section 5.1). The hybrid output remains secure as long as at least one of the two primitives does, which defeats both a future cryptographically relevant quantum computer (CRQC) running Shor's algorithm against X25519 and any currently unknown classical break of ML-KEM. The symmetric layer (ChaCha20-Poly1305 with 256-bit keys) is considered post-quantum secure: Grover's algorithm reduces the effective key strength to 128 bits, which remains computationally infeasible to brute-force. No change to the symmetric primitive is required and none is prescribed. Classical-only mode (kex-mode: classical-only) MAY be used by resource-constrained implementations (e.g. deeply embedded devices where the 1184-byte ML-KEM encapsulation key is infeasible over a low-bandwidth modem link) or for interoperability with legacy endpoints predating this draft. Classical-only mode MUST NOT be used for data requiring long-term confidentiality (conservatively, more than 10 years) due to store-now-decrypt-later attacks. Arcan Expires 29 October 2026 [Page 39] Internet-Draft MyClerk Protocol April 2026 Implementations MUST NOT negotiate classical-only mode when at least one endpoint signals the pq-mlkem768 capability and local policy requires PQ for the session's intended use. 10.6. KEX Mode Downgrade Protection Like tier negotiation (Section 10.3), KEX-mode negotiation is vulnerable to active on-path downgrade attempts. An attacker could strip mlkem-public from SESSION_INIT or remove the pq-mlkem768 capability to force classical-only. This draft binds the full handshake to the session key to make such modifications detectable. Specifically, both endpoints fold a transcript hash of the complete SESSION_INIT and SESSION_ACK byte sequences into the HKDF-SHA256 info parameter during session key derivation (see Section 5.1). Any modification of any handshake field by an intermediary causes the two endpoints to observe different transcript hashes, derive different session keys, and fail AEAD verification on the first Tier 3 or Tier 5 frame. The domain separator strings "myclerk-session-v1-hybrid" and "myclerk-session-v1-classical" additionally prevent a hybrid- derived key from being confused with a classical-derived key of the same inputs. Implementations MUST: 1. Include the exact wire-form bytes of SESSION_INIT and SESSION_ACK in the transcript hash, in the order they were sent. 2. Refuse to complete a session where the responder's selected KEX mode is weaker than the mode the initiator offered AND the local policy requires the stronger mode. 3. Log classical-only negotiations for audit purposes so operators can detect systemic downgrade attempts. 10.7. ML-KEM Implementation Hazards ML-KEM-768 implementations MUST observe the following safety properties. These are standard Fujisaki-Okamoto precautions but are called out explicitly because ahistorical implementations have repeatedly failed at them. 1. *Constant-time decapsulation.* The decapsulation routine MUST run in time independent of the secret key and the ciphertext contents, to prevent timing side channels that can recover the private key over repeated queries. Arcan Expires 29 October 2026 [Page 40] Internet-Draft MyClerk Protocol April 2026 2. *Implicit rejection.* On a ciphertext-validity failure, decapsulation MUST return a pseudo-random shared secret derived from the private key and the ciphertext (the Fujisaki-Okamoto transform's "implicit rejection" branch), NOT an error. Returning an error leaks ciphertext-validity information to the attacker. 3. *Private-key hygiene.* ML-KEM decapsulation private keys MUST be cleared from memory (e.g. via crypto/subtle.ConstantTimeCompare- adjacent zero-wipe helpers) once the session key has been derived and the ephemeral has no further use. Implementations SHOULD use a well-reviewed library rather than implementing ML-KEM from scratch. In the Go ecosystem the standard library crypto/mlkem package (available since Go 1.24) satisfies all three requirements and is the RECOMMENDED choice; the liboqs project, BoringSSL's ML-KEM implementation, and libcrux are also suitable alternatives. 11. IANA Considerations 11.1. 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 Contact: IETF Chair 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. Arcan Expires 29 October 2026 [Page 41] Internet-Draft MyClerk Protocol April 2026 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] 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 | Standard Operations (Device, | Section 5 | | | Identity, Messaging) | | +---------------+------------------------------+-------------------+ | 0x0200-0x02FF | Resource Sharing (Streams, | Section 6 | | | GPU, Routing) | | +---------------+------------------------------+-------------------+ | 0x0300-0x03FF | Federation | Section 6 | +---------------+------------------------------+-------------------+ | 0x0400-0x04FF | Billing and Economics | Section 6 | +---------------+------------------------------+-------------------+ | 0x0500-0x05FF | Virtual File System (VFS) | draft-myclerk-vfs | +---------------+------------------------------+-------------------+ | 0x0600-0x06FF | Hardware Passthrough (USB, | Section 6 | | | GPIO, I2C, SPI, CAN) | | +---------------+------------------------------+-------------------+ | 0x0700-0x07FF | Knowledge Base | Section 6 | +---------------+------------------------------+-------------------+ | 0x0800-0x08FF | Settings & Configuration | Section 6 | +---------------+------------------------------+-------------------+ | 0x0900-0x09FF | Room/Channel Management | Section 6 | +---------------+------------------------------+-------------------+ | 0x0A00-0x0AFF | Media Handling | Section 6 | +---------------+------------------------------+-------------------+ | 0x0B00-0x0BFF | Telephony (Voice, Video, | Section 6 | | | SMS, IVR) | | +---------------+------------------------------+-------------------+ | 0x0C00-0x0CFF | Calendar & Events | Section 6 | +---------------+------------------------------+-------------------+ | 0x0D00-0x0DFF | Tasks, Shopping & | Section 6 | | | Gamification | | +---------------+------------------------------+-------------------+ Arcan Expires 29 October 2026 [Page 42] Internet-Draft MyClerk Protocol April 2026 | 0x0E00-0x0EFF | Smart Home Devices | Section 6 | +---------------+------------------------------+-------------------+ | 0x0F00-0x0FFF | Automation Rules | Section 6 | +---------------+------------------------------+-------------------+ | 0x1000-0x10FF | Maya AI Assistant | Section 6 | +---------------+------------------------------+-------------------+ | 0x1100-0x11FF | Synchronization & VFS | Section 6 | | | Federation | | +---------------+------------------------------+-------------------+ | 0x1200-0x12FF | Orchestration | Section 6 | | | (Notifications, Finance) | | +---------------+------------------------------+-------------------+ | 0x1300-0x13FF | Presence & Status | Section 6 | | | (Education) | | +---------------+------------------------------+-------------------+ | 0x1400-0x14FF | Health (Social, Community) | Section 6 | +---------------+------------------------------+-------------------+ | 0x1500-0x15FF | Location & Mobility | Section 6 | +---------------+------------------------------+-------------------+ | 0x1600-0x16FF | Debug, Testing & Plugins | Section 6 | +---------------+------------------------------+-------------------+ | 0x1700-0x17FF | Mobile Device Management | [MYCLERK-OPS] | | | (MDM) | | +---------------+------------------------------+-------------------+ | 0x1800-0x18FF | Legal Documents & Care | [MYCLERK-OPS] | | | Directives | | +---------------+------------------------------+-------------------+ | 0x1900-0x19FF | Mobility & Vehicle | [MYCLERK-OPS] | | | Management | | +---------------+------------------------------+-------------------+ | 0x1A00-0x1AFF | Travel & Vacation | [MYCLERK-OPS] | +---------------+------------------------------+-------------------+ | 0x1B00-0x1BFF | Audit & Compliance | [MYCLERK-OPS] | +---------------+------------------------------+-------------------+ | 0x1C00-0x1CFF | Audio Pipeline | [MYCLERK-OPS] | +---------------+------------------------------+-------------------+ | 0x1D00-0x1DFF | Desktop Client | [MYCLERK-OPS] | +---------------+------------------------------+-------------------+ | 0x1E00-0xEFFF | Unassigned | This document | +---------------+------------------------------+-------------------+ | 0xF000-0xFFFE | Vendor Extensions (third- | This document | | | party/vendor-specific use | | | | only) | | +---------------+------------------------------+-------------------+ | 0xFFFF | Reserved | This document | +---------------+------------------------------+-------------------+ Table 30 Arcan Expires 29 October 2026 [Page 43] Internet-Draft MyClerk Protocol April 2026 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, . [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, . [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 and Transport Protocol Port Number Registry", BCP 165, RFC 6335, DOI 10.17487/RFC6335, August 2011, . [RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves for Security", RFC 7748, DOI 10.17487/RFC7748, January 2016, . [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, . [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, . [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 29 October 2026 [Page 44] Internet-Draft MyClerk Protocol April 2026 [FIPS203] National Institute of Standards and Technology, "Module- Lattice-Based Key-Encapsulation Mechanism Standard", FIPS 203, August 2024, . 12.2. Informative References [MYCLERK-OPS] Arcan, M.J., "MyClerk Protocol Application Operations Registry", Work in Progress, Internet-Draft, draft- myclerk-protocol-ops-00, 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 29 October 2026 [Page 45]