SendBeam v1.5 — Trusted Device Mesh & Automation

SendBeam v1.5 — Release Gate

The v1.5 milestone (Trusted Device Mesh & Automation: persistent pairwise device identity, mutual SPAKE2-authenticated pairing, forward-secret sendbeam/2 trusted session protocol, epoch-rotated privacy-preserving presence & LAN discovery, automated CLI/desktop transfer operations, scoped auto-accept policy containment, and browser IndexedDB participation with 9-vector adversarial attack matrix containment) gates release on the checks below, each verified against merged main.

Evidence is a deterministic unit/integration test, a verified cross-language vector fixture, or a cryptographic testbed; every transfer across the matrix terminates with an authenticated session transcript and cryptographically verified whole-file SHA-256 digest comparison.

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1. Gate Checks

#	Requirement	Result	Evidence
1	One-Time Authenticated Pairing Ceremony Pair once through an authenticated SPAKE2 ceremony with domain-separated Ed25519 signatures, canonical public key ordering, and mutually confirmed pair credentials (k_pair).	PASS	Go wire codec and handshake engine in packages/wire/pairing.go, pairing_test.go, and packages/engine/trust/pairing_coordinator.go (TestPairingCoordinator_InitiatorResponderHandshake, TestPairingCoordinator_SignatureVerificationFailureFailsClosed, TestPairingCoordinator_DeviceIDMismatchRejects). TypeScript in packages/protocol/src/pairing.ts and pairing.test.ts. Deterministic cross-language test vectors in packages/wire/testdata/pairing-vectors.json.
2	Repeat Cryptographic Connection Without Human Code (sendbeam/2) Repeat connections between paired devices authenticate cryptographically via forward-secret ephemeral ECDH (SessionMaster, k_i2r, k_r2i) and domain-separated challenges with replay and clock skew protection.	PASS	Go wire protocol and session coordinator in packages/wire/trusted_auth.go, trusted_auth_test.go, and packages/engine/trust/trusted_session.go (TestTrustedSession_InitiatorResponderMutualAuth, TestTrustedSession_ClockSkewRejection, TestTrustedSession_ReplayProtection, TestTrustedSession_RevokedPeerRefusal). TypeScript in packages/protocol/src/trusted-auth.ts and trusted-auth.test.ts. Deterministic vectors in packages/wire/testdata/trusted-session-vectors.json.
3	CLI Automation & Background Receiver Daemon sendbeam send <paths...> @<device> enables single-command sending to paired devices; sendbeam listen runs an automated background daemon with safe auto-accept policy enforcement; sendbeam devices, pair, and unpair manage mesh state with stable --json output.	PASS	CLI commands in apps/cli/cmd/sendbeam (devices.go, pair.go, unpair.go, transfers.go, listen.go, trust_config.go). Suite coverage in devices_test.go, pair_test.go, unpair_test.go, transfers_test.go, listen_test.go, and trust_config_test.go (TestListen_AutoAcceptEnforcesDestDirContainment, TestPair_InteractiveAndNonTTY, TestDevices_JsonOutputFormat). Documented in docs/trust-model.md Section 9.
4	Privacy-Preserving Remote Presence & Blinded LAN Discovery Devices discover paired peers across the Internet via 15-minute epoch-rotated blind rendezvous handles (`HMAC(k_pair, "sendbeam/2 rendezvous-handle:"		epoch)`), and on local subnets via blinded UDP multicast beacons without leaking device identity or IP addresses.
5	Native Desktop Device Manager & System Integration Desktop UI provides honest online/offline/unknown presence tracking, pairing ceremony flow, device rename, unpair/purge controls, and scoped auto-accept policy management backed strictly by the Go engine.	PASS	Desktop Go DeviceService in apps/desktop/internal/engine/device_service.go and device_service_test.go (TestDeviceService_ListDevices, TestDeviceService_UpdatePolicy, TestDeviceService_RevokeAndPurge). Desktop UI in apps/web/src/lib/trust/DevicesModal.svelte, IncomingTransferModal.svelte, and TypeScript bridge apps/web/src/lib/trust/devices.ts. Trust store and private keys remain strictly in Go host memory (0600 permissions), never exposed to WebView state.
6	Persistent Browser Trust & Origin Isolation Supported browsers participate in persistent device trust using origin-scoped IndexedDB storage (sendbeam-trust, sendbeam-secrets, sendbeam-identity) and WebCrypto subtle; unsupported browsers are cleanly capability-gated.	PASS	Browser stores in packages/protocol/src (capability.ts, indexeddb-trust-store.ts, indexeddb-secret-store.ts, browser-identity.ts). Storage operations and capability gating verified in packages/protocol/src/indexeddb-stores.test.ts (TestIndexedDBTrustStore_CRUD, TestIndexedDBSecretStore_ResolveAndPurge, TestCapability_Gating). Clearing browser site data predictably resets local trust state without polluting other origins.
7	9-Vector Adversarial Attack Matrix Containment System withstands 9 distinct adversarial attack vectors with zero security bypass or trust leakage.	PASS	Complete 9-vector security testbeds in Go (packages/wire/attack_matrix_test.go, packages/engine/trust/attack_matrix_test.go) and TypeScript (packages/protocol/src/attack-matrix.test.ts): 1. Stolen trust DB vs stolen key: Public key mismatch vs Device ID fails closed. 2. Replay attack & cloned profile: Nonce uniqueness, timestamp freshness window, and transcript binding reject replays. 3. Malicious server MITM: Ephemeral key substitution fails mutual signature verification. 4. Presence beacon replay: Stale epoch rejection after 15-min window. 5. Display name / label spoofing: Local aliases strictly isolated from cryptographic verification. 6. Downgrade attack: Capability stripping fails closed to abort, never unauthenticated transfer. 7. Stale / revoked pair credential: Revoked pair keys fail auth handshake immediately. 8. Auto-accept path escape: Traversal (..) and absolute path escapes are contained within target directory. 9. One-time transfer isolation: Standard room transfers never pollute persistent trust stores.
8	Opt-In, Path-Contained, Disk-Safe Auto-Accept Policy Automatic file acceptance is strictly opt-in per trusted device, requiring an absolute destination directory, rejecting root (/), enforcing file size caps, and validating disk space prior to reception.	PASS	Policy models and validation in packages/wire/trust_record.go (TrustPolicy.Validate(), NormalizeTransferPath()), packages/engine/trust/attack_matrix_test.go (TestAttackMatrix_Engine/Vector 3), and CLI listen_test.go. Receiver verifies path containment strictly before creating files.
9	Full Backward Compatibility with One-Time Transfers Standard ephemeral one-time room-code transfers (sendbeam/1) continue to work seamlessly without accounts, device pairing, or persistent state.	PASS	Ephemeral SPAKE2 transfers pass across the entire matrix (apps/web/src/App.test.ts, packages/engine/transfer/driver_test.go, packages/wire/transfer_loopback_test.go). UI clearly delineates between one-time room transfers and paired device operations.

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2. Differentiation Analysis: How SendBeam v1.5 Leads

Dimension	SendBeam v1.5	PairDrop / Snapdrop (WebRTC Rooms)	Syncthing / Local Mesh Tools	Cloud File Sharing (WeTransfer, Google Drive)
Identity & Trust Model	Persistent Ed25519 Device ID (sb-dev-...) with Base32 human-verifiable fingerprints and domain-separated signing.	Ephemeral browser session IDs or temporary local storage tokens; vulnerable to origin wipes and spoofing.	Cryptographic device IDs, but requires complex clustering and mutual manual configuration.	Account-based (OAuth, email, passwords); bound to centralized identity providers.
Pairing Ceremony	SPAKE2 room-bound mutual key exchange deriving cryptographically isolated pair credentials (k_pair). Zero cleartext key exposure.	Unauthenticated or basic WebRTC signaling room join; prone to server MITM key swap.	Manual device ID exchange or QR code scan; no single-command CLI ceremony.	Centralized account linkage via cloud servers.
Transfer Initiation	Direct command line & UI (sendbeam send photo.jpg @macbook) or one-click desktop send. Zero room codes on repeat transfers.	Requires opening active browser tabs simultaneously on both devices and clicking ephemeral icons.	Background sync daemon; not optimized for explicit ad-hoc file transfers.	Requires uploading file to cloud storage, generating web link, and sending link over external messenger.
Privacy & Presence	15-minute epoch-rotated blind handles and blinded UDP beacons. Signaling server learns zero device identities, IPs, or device pairings.	Signaling server sees room associations, public IP addresses, and active browser session IDs in plain text.	Discovery broadcast discloses device IDs and network addresses to local subnets and discovery servers.	Server logs every file transfer, device identity, IP address, and transfer timestamp.
Transfer Performance & Durability	High-speed direct WebRTC DataChannel with fallback encrypted relay and block-granular crash/reload resumption (resume-auth-v1).	WebRTC DataChannel without persistent block-granular crash resumption across process/browser restarts.	Block-level sync with database journaling; higher CPU and continuous disk overhead.	Upload then download (2x latency and bandwidth consumption); bounded by cloud quota.
Platform Reach	First-class CLI, Native Desktop (macOS, Windows, Linux), and Evergreen Browsers.	Browser-only (Web UI / PWA).	Native daemon only; no lightweight zero-install browser recipient.	Web and apps, but requires cloud storage accounts and uploads.

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3. Persistent Trust & Mesh Compatibility Matrix

Feature / Client Host	CLI (sendbeam)	Desktop (Wails v3)	Modern Browser (Chromium / Firefox / Safari)
Persistent Device Identity	✅ ~/.config/sendbeam/identity.key (0600)	✅ Shared Go Engine / OS keychain	✅ IndexedDB (sendbeam-identity) + WebCrypto
SPAKE2 Pairing Ceremony	✅ sendbeam pair [code]	✅ Desktop Devices UI	✅ Web UI Devices Modal
Repeat Cryptographic Auth (sendbeam/2)	✅ Full Initiator & Responder	✅ Full Initiator & Responder	✅ Full Initiator & Responder
Targeted Sending (@device)	✅ sendbeam send <file> @device	✅ Desktop Quick-Send Flow	✅ Web UI Devices Send Dialog
Automated Listener Daemon	✅ sendbeam listen	✅ Background presence listener	⚠️ Active browser tab only
Opt-In Auto-Accept Policy	✅ Absolute dest dir, size caps	✅ UI policy config with dir picker	⚠️ Explicit user approval per transfer
LAN Blinded Beacon Discovery	✅ UDP Multicast 224.0.0.251:5354	✅ UDP Multicast 224.0.0.251:5354	⚠️ WebRTC / Signaling Rendezvous
One-Time Transfer Interop (sendbeam/1)	✅ Full Support	✅ Full Support	✅ Full Support

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4. Security Invariants & Attack Matrix Verification

All security properties are strictly maintained across the entire codebase:

• Strict Identity Binding: Display names and local labels are purely cosmetic and local; all cryptographic authorization is bound strictly to canonical DeviceID (sb-dev-...) derived from the Ed25519 public key.
• Transcript Freshness & Anti-Replay: Every sendbeam/2 trusted session incorporates fresh 256-bit initiator and responder nonces, session timestamps with a strict ±5 minute tolerance window, and ephemeral ECDH keys.
• Fail-Closed Revocation: Unpairing or revoking a device purges the pairwise credential (k_pair) locally. Any future connection attempts from that device fail closed immediately with ErrUntrustedPeer.
• Auto-Accept Path Confinement: Auto-accept destinations must be absolute paths (root / rejected). All inbound file paths are sanitized via wire.NormalizeTransferPath(); paths with parent directory traversal (..) or absolute references fail closed and cannot escape the destination boundary.
• One-Time Isolation: Standard one-time transfers execute under isolated SPAKE2 credentials and never write to or read from the persistent trust database.
• Origin-Scoped Browser Storage: Browser trust records and pairwise secrets reside in origin-isolated IndexedDB databases. Clearing site data predictably revokes all local browser credentials without leaking key material across origins.

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5. Milestone Sign-Off Checklist

• All 8 milestone PRs (V15-PR01 through V15-PR08) implemented and verified.
• 100% green CI across all 21 verification gates (Go tests with -race, TypeScript checks, ESLint, Prettier, e2e Playwright tests, cross-platform distribution builds).
• Zero brand regressions or stale naming leaks.
• Comprehensive documentation in docs/trust-model.md, docs/threat-model.md, docs/compat-matrix.md, docs/protocol.md, and README.md.
• Release gate signed off and verified against merged main.