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ART post-quantum agents transport ALPN The Native Post-Quantum Agent Messaging Protocol (N-PAMP) is a binary, multi-channel, wire-level protocol for authenticated communication between autonomous software agents. N-PAMP operates beneath application-layer agent protocols and provides a single fixed-size frame format, a registry of multiplexed channels, and three escalating security profiles (Standard, High, and Sovereign) built on standard post-quantum and classical cryptography. The protocol uses a hybrid key-encapsulation mechanism combining X25519 with ML-KEM, authenticated encryption with associated data, and a forward-secure key schedule. N-PAMP runs over QUIC as its primary transport and over TCP with TLS 1.3 as a fallback, negotiated via the Application-Layer Protocol Negotiation (ALPN) identifier "n-pamp/2". This document describes the wire format, channel architecture, profile negotiation, and cryptographic suites of N-PAMP, and reserves code-point ranges for extensions defined in companion specifications.

Introduction Autonomous software agents increasingly communicate with one another over long-lived associations that carry control traffic, persistent state, capability delegation, identity attestation, and operational telemetry on a single connection. Existing transport-layer protocols such as TLS 1.3 and QUIC , and application-layer agent protocols layered above them, do not by themselves provide a unified binary frame format with semantic channel multiplexing, profile-negotiated cryptographic strength, and mandatory authenticated encryption tailored to agent-to-agent traffic. N-PAMP addresses this gap. It defines a single fixed-size frame header, a set of multiplexed channels each carrying a distinct class of agent traffic, and three negotiated security profiles that hold the wire format constant while escalating the cryptographic primitives and operational requirements. All three profiles employ a hybrid key-encapsulation mechanism (KEM) combining the classical X25519 key agreement with a NIST-standardized module-lattice KEM (ML-KEM, ), so that the confidentiality of an association is preserved if either the classical or the post-quantum component remains unbroken. N-PAMP is deliberately scoped as a transport substrate. It does not define application-layer semantics for the data carried on its channels; those are the subject of companion specifications. This document specifies the wire format, the channel registry, profile negotiation, and the cryptographic suites, and it reserves code-point ranges so that companion extensions can be defined without colliding with the core protocol.

Goals The design goals of N-PAMP are: Cryptographic agility within a stable wire format. The frame format does not change between profiles; the cryptographic primitives, modes, and operational requirements do. Defense in depth through hybrid post-quantum and classical key establishment, authenticated encryption, and a forward-secure key schedule. Channel multiplexing so that a single association can carry several classes of agent traffic with independent sequence spaces and per-channel keying. Interoperability across profiles, so that an endpoint operating at a higher profile MAY interoperate with a lower-profile peer when local policy permits.

Non-Goals This document does NOT: Replace TLS for ordinary web traffic. N-PAMP is purpose-built for autonomous-agent, multi-channel traffic over long-lived associations. Define application-layer semantics for the data carried on its channels. Define a general-purpose IP-layer tunneling or VPN protocol.

Terminology For the purposes of this document:

Association:

A long-lived, cryptographically authenticated session between two N-PAMP endpoints, identified by a stable Association ID.

Channel:

A semantic multiplexing lane within an association, identified by a 16-bit Channel ID, carrying one class of agent traffic with its own sequence space.

Frame:

The atomic unit of transmission, consisting of a fixed 36-octet header, optional extension TLVs, and an AEAD-protected payload.

Profile:

One of three negotiated levels of cryptographic strength and operational requirement (Standard, High, Sovereign).

Conventions and Definitions 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 when, and only when, they appear in all capitals, as shown here.

Protocol Overview N-PAMP is a binary protocol. Every unit of communication is a frame consisting of a fixed 36-octet header (), zero or more extension TLVs, and a payload protected by an authenticated-encryption-with-associated-data (AEAD) construction . Frames are carried on channels (), each of which has an independent per-direction sequence space. An N-PAMP association is established by a handshake that: establishes a hybrid X25519 + ML-KEM shared secret; negotiates a security profile, a KEM, a signature algorithm, and one or more AEAD suites; authenticates both peers by signing a transcript that binds the negotiated parameters and both peer identities; and derives a forward-secure key schedule from which per-channel, per-direction traffic keys are obtained. The negotiated profile, the KEM identifier, the signature identifier, the selected AEAD suite(s), and both peer identities are all bound into the handshake transcript and confirmed by a Finished message authentication code (MAC). A man-in-the-middle that alters any negotiated parameter or substitutes an identity invalidates the Finished MAC and aborts the handshake; this is the structural defense against downgrade, unknown-key-share, and identity-substitution attacks (see ). N-PAMP uses QUIC (secured with TLS 1.3, ) as its primary transport and TCP with TLS 1.3 as a fallback. In both cases, the application protocol is negotiated using the ALPN extension with the identifier "n-pamp/2" ().

Wire Format

Frame Structure Every N-PAMP frame has the following structure:

The 36-octet header is fixed-size. Zero or more extension TLVs MAY accompany a frame. The payload is AEAD-sealed, and the associated data covers the 21-octet header prefix (octets 0-20, through the Payload Length field, the same octets protected by the header CRC32C) so that any modification to those header fields is detected on decryption.

Frame Header The fixed header is 36 octets, laid out as follows. Multi-octet integers are encoded in network byte order (big-endian) unless stated otherwise.

The fields are: Offset Size Field Description 0-3 4 octets Magic ASCII "NPAM" (0x4E 0x50 0x41 0x4D). 4 4 bits Ver Protocol major version, the high nibble of octet 4. The value 0x2 designates the wire format described in this document (wire major version 2). 4 4 bits Flags The low nibble of octet 4 (see ). 5-6 2 octets Frame Type Frame type within the channel (see ). 7-8 2 octets Channel ID The semantic channel (). 9-16 8 octets Sequence Number Per-(channel, direction) monotonic sequence number, starting at 0. 17-20 4 octets Payload Length Byte count of the payload following the header. 21-24 4 octets CRC32C CRC32C (Castagnoli polynomial 0x1EDC6F41) computed over header octets 0-20. Receivers MUST validate it before processing any other header field. 25-35 11 octets Reserved MUST be zero; receivers MUST reject frames whose reserved octets are non-zero. All multi-octet integers are big-endian. The Ver field carries the wire major version; the value 0x02 corresponds to the ALPN identifier "n-pamp/2".

Frame Flags The low nibble of header octet 4 carries four flag bits: Bit Name Meaning 0 (0x01) URG Urgent-priority scheduling. 1 (0x02) ENC Payload is AEAD-encrypted. 2 (0x04) COMP Payload is compressed. 3 (0x08) FRAG Frame is a fragment of a larger logical message.

Extension TLVs Zero or more Type-Length-Value (TLV) extensions MAY accompany a frame. Each TLV is encoded as:

Type and Length are 16-bit unsigned integers in network byte order; Length is the byte count of Value (0 to 65535). A receiver that encounters an unknown TLV whose Type has the high bit (0x8000) clear MUST ignore that TLV. A receiver that encounters an unknown TLV whose Type has the high bit (0x8000) set MUST treat it as a forward-incompatible extension and reject the frame. The TLV type registry maintained by this specification is given in .

Payload Encoding The payload carries a frame-type-specific body. The body MAY be encoded in a binary serialization, in deterministic CBOR , or as raw octets. The selected encoding is signaled within the channel-local interpretation of the Frame Type field.

Reserved Frame Types Each channel defines its own frame types in the 0x0000-0xFFFF space. The following frame types are reserved across all channels and have the same meaning on every channel: Type Name Description 0x0000 (reserved) Reserved; MUST NOT be used as a frame type. 0x0001 PING Liveness probe. 0x0002 PONG Reply to PING. 0x0003 CLOSE Authenticated close; AEAD-protected. 0x0004 CLOSE_ACK Reply to CLOSE. 0x0005 ERROR Error report; AEAD-protected. 0x0006 KEY_UPDATE Initiate key update for this (channel, direction). 0x0007 KEY_UPDATE_ACK Acknowledge key update. 0x0008 PATH_CHALLENGE Path-migration challenge. 0x0009 PATH_RESPONSE Path-migration response. 0x000A FLOW_UPDATE Connection-level flow-control credit update. Channel-specific frame types begin at 0x0100 within each channel's frame namespace. Frame-type code points at or above 0x0030 that are not reserved here, and in particular the ranges enumerated in , are reserved for extensions defined in companion specifications. The Control channel (0x0000) assigns the following channel-specific frame types for the N-PAMP handshake (): Type Name Description 0x0100 CLIENT_HELLO First handshake flight (client); cleartext. 0x0101 SERVER_HELLO Second handshake flight (server); cleartext. 0x0102 SERVER_AUTH Server authentication flight; AEAD-protected. 0x0103 CLIENT_AUTH Client authentication flight; AEAD-protected.

CLOSE Frame A CLOSE frame is authenticated like any other frame. A receiver MUST verify the AEAD tag before honoring a close. An unauthenticated or forged CLOSE frame MUST be dropped and SHOULD be counted as a security event.

Channel Architecture N-PAMP multiplexes traffic over channels identified by a 16-bit Channel ID. Each channel carries one class of agent traffic and has an independent per-direction sequence space and independent traffic keys (). A peer that has not advertised a channel during the handshake MUST NOT receive frames on that channel; frames on an unadvertised channel MUST be dropped.

Core Channel Registry The following channels are defined and maintained by this specification: ID Name Purpose Min Profile Direction 0x0000 Control Connection control, handshake completion, capability epoch Standard Bidirectional 0x0001 Memory Persistent-state create/read/update/delete and retrieval Standard Multi-stream 0x0002 Capability Capability issuance, delegation, revocation, lookup Standard Bidirectional 0x0003 Identity Identity resolution, attestation, presence Standard Bidirectional 0x0004 Governance Policy proposals, votes, quorum closure High Bidirectional 0x0005 Immune Anomaly reports and defensive gossip Standard Bidirectional 0x0006 Federation Cross-instance synchronization and gossip High Multi-stream 0x0007 Settlement Agent-to-agent settlement and receipts Standard Bidirectional 0x0008 Compliance Attestation and regulatory export High Bidirectional 0x0009 Sensory Bulk telemetry and low-priority observations High Multi-stream 0x000A Telemetry Operational metrics and health reporting Standard Bidirectional 0x000B Audit Audit-epoch commitments and transparency-log entries Sovereign Bidirectional 0x000C Stream Multiplexed full-duplex streaming (tokens, audio, video, file transfer) Standard Multi-stream 0x000D Bridge Encapsulation of external agent protocols within N-PAMP frames Standard Bidirectional 0x000E Commerce Multi-party agentic commerce and payment mandates Standard Bidirectional 0x000F Interaction Agent-to-human user-interface events Standard Bidirectional 0x0010 Discovery Agent, tool, and service discovery and capability advertisement Standard Bidirectional 0x0011 Workflow Multi-agent orchestration and task delegation Standard Bidirectional 0x0012 Knowledge Retrieval queries with ranked results and provenance Standard Multi-stream 0x0013 Spatial Physical-world state for robotics and IoT (high-frequency) High Multi-stream The Min Profile column gives the lowest profile at which a channel may be enabled; a channel is available at that profile and at every higher profile (for example, a "High" channel is available at High and Sovereign). The Audit channel is enabled by default only at Sovereign; other profiles MAY enable it. The Control and Immune channels SHOULD be scheduled at higher priority than bulk channels (Memory, Sensory, Telemetry) during congestion. All N-PAMP channels are full-duplex: each peer maintains an independent send and receive sequence space and independent per-direction traffic keys, so both peers MAY transmit on a channel simultaneously. The Direction column classifies each channel as follows: Direction Meaning Bidirectional Both peers send and receive frames on a single stream. Multi-stream Bidirectional, and the channel MAY open multiple concurrent transport streams within its stream family. The Stream channel (0x000C) provides general-purpose multiplexed full-duplex streaming, carrying concurrent bidirectional sub-streams (for example token, audio, video, and file-transfer streams), each with independent flow control. Channel IDs not listed in , and in particular the ranges enumerated in , are reserved for extensions defined in companion specifications.

Profile Negotiation N-PAMP defines three security profiles. The profiles share one wire format and differ in the cryptographic primitives and operational requirements they mandate. Each profile is an escalation of the previous one in cryptographic strength. Profile Code Summary Standard 0x01 Baseline hybrid post-quantum security. High 0x02 Stronger KEM parameters and stronger hash; downgrade refusal to Standard. Sovereign 0x03 Highest standard-crypto strength; downgrade refusal below Sovereign. Profile code points 0x00 and 0x04-0xFF are reserved by this specification. The profile is offered by the client and selected by the server during the handshake, and is carried in the handshake transcript. Because the profile is part of the transcript that the Finished MAC covers, an attacker who strips a profile from the offer or forces a lower selection invalidates the MAC and aborts the handshake. The profile invariants are: Property Standard High Sovereign Minimum KEM X25519MLKEM768 X25519MLKEM1024 X25519MLKEM1024 Allowed signatures Ed25519 Ed25519, ML-DSA-87 ML-DSA-87 KDF hash SHA-256 SHA-384 SHA-384 Per-frame AEAD diversification Off On On Downgrade refusal Off Refuses Standard Refuses below Sovereign Mandatory key update Yes Yes (tighter bounds) Yes (tightest bounds) The server MUST select a profile from the client's offered set. The selected profile MUST be no lower than the server's configured minimum acceptable peer profile. A Sovereign server with a minimum acceptable peer profile of Sovereign completes a handshake only when the client offers Sovereign and Sovereign is selected. A High or Sovereign endpoint MAY interoperate with a lower-profile peer for read-only or capability-discovery operations when local policy permits, by accepting a lower selected profile; otherwise it refuses the downgrade as shown above.

Cryptographic Suites All cryptographic primitives used by N-PAMP are published standards.

Key Encapsulation Mechanisms Code point Name Profiles 0x11ec X25519MLKEM768 Standard, High 0x11ed X25519MLKEM1024 High, Sovereign Both are hybrid KEMs combining X25519 ECDH with ML-KEM (ML-KEM-768 and ML-KEM-1024, respectively). The two shared secrets are concatenated as (ML-KEM shared secret || X25519 shared secret) and supplied as input keying material to HKDF-Extract . The ML-KEM shared secret is placed first so the FIPS-approved key-establishment output leads the HKDF input (), matching the X25519MLKEM768 construction of . The suite name lists X25519 first, but the shared-secret concatenation and the on-wire KEMShare/KEMCiphertext layout are ML-KEM-first. The Sovereign profile MUST NOT accept X25519MLKEM768.

Authenticated Encryption Code point Name Key Nonce Tag 0x0001 AES-256-GCM 32 12 16 0x0002 ChaCha20-Poly1305 32 12 16 AES-256-GCM is used as specified for AEAD ciphers in ; ChaCha20-Poly1305 is used as specified in . Endpoints operating at the High and Sovereign profiles MUST support both AEAD suites because per-frame AEAD diversification at those profiles selects between them. Endpoints operating at the Standard profile MUST support at least one of the two.

Signatures Code point Name Usage Profiles 0x0807 Ed25519 Identity, capability tokens All 0x0905 ML-DSA-87 Identity, audit epoch High, Sovereign Ed25519 is used as specified in . ML-DSA-87 is the module-lattice-based digital signature algorithm standardized in . The Sovereign profile uses ML-DSA-87 for identity and audit signatures.

Key Derivation and Hashing All key derivation uses HKDF . The KDF hash is SHA-256 at the Standard profile and SHA-384 at the High and Sovereign profiles. The HKDF-Expand-Label construction follows TLS 1.3 , with the literal label prefix "n-pamp " (with the trailing space) in place of TLS 1.3's "tls13 ", providing domain separation from TLS 1.3, from QUIC, and from earlier N-PAMP versions. A conforming implementation MUST use the "n-pamp " prefix; use of the "tls13 " prefix is non-conformant. The full key-schedule ladder is specified in .

Key Schedule and Nonces Traffic secrets are derived per (direction, epoch, AEAD suite, channel) tuple, so that no two distinct contexts share a key. Each traffic secret yields an AEAD key, an AEAD initialization vector, and a header-protection key by HKDF-Expand-Label. The per-frame nonce is the AEAD IV exclusive-ORed with the left-zero-padded sequence number, identical in form to the construction used in TLS 1.3 and QUIC . This namespace partitioning prevents cross-direction, cross-suite, and cross-channel nonce reuse, and supports forward secrecy: on key update, traffic secrets for the new epoch are derived afresh and the prior epoch's secrets are zeroized.

Random Number Generation All randomness that participates in security MUST come from a cryptographically secure random number generator. Implementations MUST NOT use a non-cryptographic source for any field that participates in security.

Handshake The N-PAMP handshake is a 1.5-RTT, mutually-authenticated exchange of four frames on the Control channel (0x0000, sequence 0), after which both peers are authenticated and a forward-secure key schedule is established. It reuses TLS 1.3 constructions (HKDF-Expand-Label, CertificateVerify, Finished) with N-PAMP framing and context; each divergence from TLS 1.3 is noted inline in the relevant subsection below. One construction serves all three profiles; a profile selects a parameter row (see and ), so H and HashLen below are read from the negotiated profile.

Message Flow Flight Frame Type TLVs (in order) Encryption 1 CLIENT_HELLO 0x0100 ProfileOffer, KEMOffer, SigOffer, AEADOffer, KEMShare cleartext 2 SERVER_HELLO 0x0101 ProfileSelect, KEMSelect, SigSelect, AEADSelect, KEMCiphertext cleartext 2 SERVER_AUTH 0x0102 IdentityKey, CertVerify, Finished AEAD-sealed 3 CLIENT_AUTH 0x0103 IdentityKey, CertVerify, Finished AEAD-sealed There is no separate Finished frame; the Finished MAC is a TLV inside each AUTH frame. Each frame is a standard 36-octet N-PAMP frame () on channel 0x0000 with sequence 0; the AUTH frames set FlagENC and are AEAD-sealed (). A server reaches the Established state only after it has verified CLIENT_AUTH; the master secret is derived at the client-authentication boundary.

Transcript The handshake transcript is a running byte buffer; a transcript hash is H over all bytes absorbed so far. Unlike TLS 1.3 Section 4.4.1, which hashes whole handshake messages, N-PAMP absorbs at per-TLV granularity and absorbs only the 2-octet big-endian frame type of each frame: the remaining 34 header octets and the AEAD tag are NOT absorbed. For each frame, the 2-octet frame type is absorbed, followed by each of that frame's TLVs in canonical Type(2) || Length(2) || Value form, in order. Five transcript hashes are named: Symbol Absorbed through Used by TH_kem CLIENT_HELLO and SERVER_HELLO TLVs handshake-secret labels TH_sId ... server IdentityKey server CertVerify signs this TH_sCV ... server CertVerify (excludes server Finished) server Finished MACs this TH_cId ... server Finished, CLIENT_AUTH, client IdentityKey client CertVerify signs this TH_cCV ... client CertVerify (excludes client Finished) client Finished MACs this; master derived from this Because both peers absorb the identical decoded on-wire TLV bytes, their transcripts are byte-identical.

Key Schedule The key schedule is a single HKDF-Extract followed by sibling HKDF-Expand-Label derivations (simpler than TLS 1.3 Section 7.1's three-stage chain; N-PAMP defines no PSK or 0-RTT in this binding). HKDF-Expand-Label is as in TLS 1.3 Section 7.1 with the N-PAMP label prefix "n-pamp " (with the trailing space) in place of "tls13 ":

The KEM output () is the 64-octet value (ML-KEM shared secret || X25519 shared secret), fed directly as input keying material:

The Extract salt is HashLen zero octets (the default). The master secret is derived only at the client-authentication boundary, from TH_cCV. Handshake-phase traffic keys descend from c_hs_secret and s_hs_secret; application-phase traffic keys descend from master, using the traffic-secret construction of . Because the parents differ, an identical (direction, epoch, suite, channel) tuple yields different (key, iv) across the handshake and application phases, so no (key, nonce) pair is shared across phases.

Authentication

CertVerify The CertVerify TLV (0x0A) carries a signature over the transcript, structured as in TLS 1.3 Section 4.4.3 with N-PAMP context strings:

The context strings are fixed protocol constants (they are the values bound into the reference implementations and the interoperability test vectors) and do not change with the Internet-Draft revision number. The signed transcript_hash is TH_sId (server) or TH_cId (client): the transcript through the signer's own IdentityKey, before its own CertVerify. The TLV value is the 2-octet SignatureScheme (Ed25519 = 0x0807) followed by the signature, whose length is delimited by the TLV Length. A verifier MUST reject a signature scheme it did not negotiate and MUST check the role: the differing context string makes a server CertVerify unusable as a client CertVerify.

Finished The Finished TLV (0x0B) carries an HMAC per TLS 1.3 Section 4.4.4, keyed by the sender's handshake traffic secret:

BaseKey is c_hs_secret or s_hs_secret per direction; the HMAC hash is H. The MAC'd transcript_hash is TH_sCV (server) or TH_cCV (client): the transcript through the signer's own CertVerify, excluding its own Finished. The verify_data length is HashLen. Verification MUST be constant-time and MUST abort on mismatch.

AUTH-Frame Sealing SERVER_AUTH and CLIENT_AUTH are sealed with the negotiated AEAD under the per-direction handshake key and IV (): FlagENC is set, Channel is 0x0000, and Seq is 0. The AAD is the 21-octet frame header prefix and the nonce is the IV exclusive-ORed with the sequence number, as in . On open, exactly three TLVs -- IdentityKey, CertVerify, Finished, in that order -- MUST be present.

Downgrade Protection The negotiated profile and algorithm selections are carried in the cleartext CLIENT_HELLO and SERVER_HELLO and are absorbed into the transcript that both the Finished MAC and CertVerify cover. Stripping a profile from an offer, or forcing a lower selection, therefore invalidates the Finished MAC and aborts the handshake. N-PAMP uses this transcript binding for downgrade protection rather than a TLS-style ServerHello.Random sentinel.

Extension Points N-PAMP reserves code-point ranges for extensions defined in companion specifications. The core protocol in this document neither defines nor requires any extension; it only reserves the ranges below so that extensions can be specified without colliding with the core wire format. The algorithms and semantics that occupy these ranges are out of scope for this document and are defined in companion specifications.

Reserved Frame-Type Ranges The following per-channel frame-type code points are reserved for extensions defined in companion specifications: Range Reserved for 0x0035 - 0x0036 Memory-channel eviction and revive extension frames 0x0060 - 0x0063 Capability-channel token extension frames 0x0080 - 0x0080 Control-channel flow-extension frames 0x0090 - 0x0090 Audit-channel per-frame integrity-extension frames 0x00A0 - 0x00A3 Settlement/Audit batch-commitment extension frames 0x00B0 - 0x00B4 Governance-channel quorum extension frames 0x00C0 - 0x00C4 Immune-channel propagation extension frames

Reserved TLV Tags The TLV types 0x0010, 0x0013, and 0x0014 are reserved for extension TLVs defined in companion specifications. TLV types in the range 0x8000-0xFFFF remain reserved as forward-incompatible extension points per .

Reserved Channel-ID Range Channel IDs in the range 0x0014-0xFFFF are reserved. Channels 0x0014-0x001F are reserved for future core additions by this specification; 0x0020-0xEFFF are reserved for extension channels defined in companion specifications; 0xF000-0xFFFE are GREASE values that receivers MUST ignore; and 0xFFFF MUST NOT appear on the wire. The specific extension assignments are out of scope for this document. No algorithms, parameters, or semantics for any reserved range are defined in this document.

IANA Considerations

ALPN Protocol Identifier IANA has registered the following value in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry established by . The registration was made under an earlier version of this document; IANA is requested to update its reference to the current version: Protocol Identification Sequence Reference N-PAMP, wire major version 2 0x6E 0x2D 0x70 0x61 0x6D 0x70 0x2F 0x32 ("n-pamp/2") (this document) The identification sequence is the 8-octet UTF-8 string "n-pamp/2". The trailing digit "2" equals the N-PAMP wire major version (the value 0x02 carried in the Ver field of the frame header, ). The registration policy for the ALPN registry is Expert Review . The earlier identifier "n-pamp/1" is deprecated. Implementations SHOULD NOT negotiate "n-pamp/1" for new associations. Future wire major versions will use distinct ALPN identifiers (for example, "n-pamp/3").

URI Scheme Registration The "npamp" URI scheme has been provisionally registered in the "Uniform Resource Identifier (URI) Schemes" registry, following the template and the provisional-registration procedure (First Come First Served) of , under an earlier version of this document; IANA is requested to update its reference to the current version. The registration template follows: Scheme name: npamp Status: Provisional Applications/protocols that use this scheme: The protocol defined in this document (N-PAMP). An "npamp" URI names an N-PAMP endpoint and an optional resource path within that endpoint. URI scheme syntax: The "npamp" scheme uses the generic URI syntax of :

where "authority", "path-abempty", and "query" are as defined in . The "authority" component identifies the N-PAMP endpoint (host and optional port). N-PAMP does not reserve a fixed default port; the underlying transport is negotiated as described in . Encoding considerations: "npamp" URIs are processed as defined in ; non-ASCII characters in the path or query components are percent-encoded UTF-8 octets. Interoperability considerations: None beyond those of . The scheme carries no protocol semantics of its own; all behavior is defined by N-PAMP. Security considerations: See . An "npamp" URI is only an identifier. Connecting to an "npamp" endpoint invokes the N-PAMP handshake and its authentication, confidentiality, and downgrade protections; dereferencing an "npamp" URI MUST NOT bypass the security profile negotiated by N-PAMP. Contact: Shawn Sammartano, BubbleFish Technologies, Inc. Change controller: Shawn Sammartano, BubbleFish Technologies, Inc. Reference: This document.

Registries Maintained by This Specification The N-PAMP channel registry (), the frame-type registry (), and the TLV type registry () are defined and maintained within this specification. Because this document is published through the Independent Submission stream, it does not request the creation of new IANA-hosted registries for these code points; the registries are normative within this document and are extended by companion specifications and by future revisions of this document, not by IANA registration actions.

TLV Type Registry The following TLV tags are defined by this specification. Tags marked "reserved" are described in . Tag Name Length Description 0x01 ProfileOffer var Profiles offered by the client, one octet per profile (handshake only). 0x02 ProfileSelect 1 Profile selected by the server (handshake only). 0x03 KEMOffer var KEMs offered by the client. 0x04 KEMSelect 2 KEM selected by the server. 0x05 SigOffer var Signature algorithms offered. 0x06 SigSelect 2 Signature algorithm selected. 0x07 KEMShare var Public KEM share. 0x08 KEMCiphertext var KEM encapsulation ciphertext. 0x09 IdentityKey var Sender's identity public key (handshake AUTH; see ). 0x0A CertVerify var Signature over the transcript (handshake AUTH; see ). 0x0B Finished var HashLen-octet Finished MAC (handshake AUTH; see ). 0x0C AEADOffer var AEAD suites offered by the client (handshake only). 0x0D AEADSelect 2 AEAD suite selected by the server (handshake only). 0x10 (reserved) var Reserved for a companion specification. 0x12 AnomalyCharge 32 Per-frame integrity charge. 0x13 (reserved) var Reserved for a companion specification. 0x14 (reserved) 32 Reserved for a companion specification (handshake only). 0x15 PathChallenge 32 Path-migration challenge nonce. 0x16 PathResponse 64 Path-migration response. 0x17 KeyUpdateMarker 8 Key-update epoch marker. 0x18 ProtectionMode 1 Protection-mode selector. 0x8000-0xFFFF (reserved) -- Forward-incompatible extension points (Type high bit set).

Security Considerations This section follows the spirit of . N-PAMP inherits the security properties of its underlying transports, TLS 1.3 and QUIC , and adds the considerations below.

Hybrid Key Establishment Every profile uses a hybrid KEM that concatenates an ML-KEM shared secret with an X25519 shared secret (ML-KEM first) before key derivation. The confidentiality of an association is preserved as long as at least one of the two components remains unbroken; an adversary must defeat both the classical and the post-quantum component to recover traffic keys. N-PAMP makes no claim of unconditional or "quantum-proof" security; it provides post-quantum hybrid security against the adversaries addressed by its component primitives.

Downgrade, Unknown-Key-Share, and Identity Substitution The negotiated profile, KEM, signature algorithm, AEAD suite(s), and both peer identities are bound into the handshake transcript and confirmed by the Finished MAC (, ). Altering any negotiated parameter, stripping a profile from the offer, or substituting a peer identity invalidates the Finished MAC and aborts the handshake. The High and Sovereign profiles additionally refuse to complete at a profile below their configured minimum.

Authenticated Encryption and Nonce Management All payloads are protected by AEAD . Traffic keys are partitioned per (direction, epoch, suite, channel), which structurally prevents nonce reuse across directions, AEAD suites, and channels. AEAD tag verification MUST be performed before any payload is processed, and equality comparisons of authentication values MUST be constant-time to avoid timing side channels.

Replay Each (channel, direction) pair maintains a sliding replay window over sequence numbers. Frames outside the window or already recorded within it MUST be rejected. Where 0-RTT data is permitted, it MUST be limited to idempotent operations and protected against replay by an anti-replay mechanism scoped to the current epoch; the Sovereign profile disables 0-RTT entirely.

Forward Secrecy and Key Update Endpoints MUST perform key updates within profile-specific bounds on elapsed time, frames sent, and bytes protected, with the tightest bounds at the Sovereign profile. On key update, the prior epoch's traffic secrets MUST be zeroized so that compromise of the current epoch does not expose previously protected traffic. Rotation of the master secret requires a fresh handshake.

Connection Migration When carried over QUIC, an endpoint MUST validate a peer's new path with a challenge-response exchange (PATH_CHALLENGE / PATH_RESPONSE) before accepting an address change, to prevent off-path migration spoofing.

Authenticated Close CLOSE frames are AEAD-protected and MUST be verified before being honored, so that an off-path attacker cannot tear down an association with a forged CLOSE.

Extension Points The reserved code-point ranges in carry no algorithms or semantics in this document. Any security properties of extensions occupying those ranges are the responsibility of the companion specifications that define them and are out of scope here.

Implementation Considerations Where the wire format requires deterministic encoding (for example, deterministic CBOR or canonical integer encodings), implementations MUST produce byte-identical output for identical inputs, because non-deterministic encodings can invalidate transcript and integrity computations across peers.

In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document defines algorithms for Authenticated Encryption with Associated Data (AEAD), and defines a uniform interface and a registry for such algorithms. The interface and registry can be used as an application-independent set of cryptoalgorithm suites. This approach provides advantages in efficiency and security, and promotes the reuse of crypto implementations. [STANDARDS-TRACK] This document specifies a simple Hashed Message Authentication Code (HMAC)-based key derivation function (HKDF), which can be used as a building block in various protocols and applications. The key derivation function (KDF) is intended to support a wide range of applications and requirements, and is conservative in its use of cryptographic hash functions. This document is not an Internet Standards Track specification; it is published for informational purposes. This document describes a Transport Layer Security (TLS) extension for application-layer protocol negotiation within the TLS handshake. For instances in which multiple application protocols are supported on the same TCP or UDP port, this extension allows the application layer to negotiate which protocol will be used within the TLS connection. A Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK] This document updates the guidelines and recommendations, as well as the IANA registration processes, for the definition of Uniform Resource Identifier (URI) schemes. It obsoletes RFC 4395. This document describes elliptic curve signature scheme Edwards-curve Digital Signature Algorithm (EdDSA). The algorithm is instantiated with recommended parameters for the edwards25519 and edwards448 curves. An example implementation and test vectors are provided. This document defines the ChaCha20 stream cipher as well as the use of the Poly1305 authenticator, both as stand-alone algorithms and as a "combined mode", or Authenticated Encryption with Associated Data (AEAD) algorithm. RFC 7539, the predecessor of this document, was meant to serve as a stable reference and an implementation guide. It was a product of the Crypto Forum Research Group (CFRG). This document merges the errata filed against RFC 7539 and adds a little text to the Security Considerations section. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack. This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format. This document defines the core of the QUIC transport protocol. QUIC provides applications with flow-controlled streams for structured communication, low-latency connection establishment, and network path migration. QUIC includes security measures that ensure confidentiality, integrity, and availability in a range of deployment circumstances. Accompanying documents describe the integration of TLS for key negotiation, loss detection, and an exemplary congestion control algorithm. This document describes how Transport Layer Security (TLS) is used to secure QUIC. National Institute of Standards and Technology (NIST) National Institute of Standards and Technology (NIST) National Institute of Standards and Technology (NIST) Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226. All RFCs are required to have a Security Considerations section. Historically, such sections have been relatively weak. This document provides guidelines to RFC authors on how to write a good Security Considerations section. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. PQShield AWS Cloudflare University of Waterloo This draft defines three hybrid key agreement mechanisms for TLS 1.3 - X25519MLKEM768, SecP256r1MLKEM768, and SecP384r1MLKEM1024 - that combine the post-quantum ML-KEM (Module-Lattice-Based Key Encapsulation Mechanism) with an ECDHE (Elliptic Curve Diffie- Hellman) exchange.

Acknowledgments The author thanks the reviewers of earlier N-PAMP drafts for their feedback.

Changes Since draft-bubblefish-npamp-00 This revision makes the following changes relative to draft-bubblefish-npamp-00: Hybrid KEM combiner order (wire-breaking). The hybrid shared-secret concatenation for both X25519MLKEM768 and X25519MLKEM1024 is now ML-KEM_SS || X25519_SS (ML-KEM first), replacing the X25519-first order of draft-00, so that the FIPS-approved key-establishment output leads the HKDF input per NIST SP 800-56C Rev. 2 () and matches the construction of . This changes the derived keys and is NOT interoperable with draft-00. Handshake binding. Adds the normative 1.5-RTT mutually-authenticated handshake (): the four-frame flow, the per-TLV transcript, the single HKDF-Extract key schedule with the "n-pamp " label prefix, CertVerify, Finished, AUTH-frame sealing, and downgrade protection. Handshake code points. Assigns the Control-channel handshake frame types 0x0100-0x0103 and the handshake TLV tags 0x09-0x0D (IdentityKey, CertVerify, Finished, AEADOffer, AEADSelect). ProfileOffer length. Corrects the ProfileOffer (TLV 0x01) length from a fixed 4 to a variable list of one-octet profile identifiers, matching the other negotiation offers and the reference implementations. IANA Considerations. Updated to reflect that the ALPN identifier "n-pamp/2" and the "npamp" URI scheme are already registered, requesting a reference update to this revision rather than a new assignment.