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Version: 0.2.71

Release Notes

This page describes changes, security impact, operational impact, and known limitations for NoxTLS 0.2.71.

For source and binary artifacts, see Releases on GitHub.

Use the version dropdown in the navbar to view docs (and release notes) for other versions.

0.2.71​

Release date: 2026-08-27 Release type: Feature + hardening release (caller-polled TLS, resumption, and diagnostic API additions)

Executive Summary​

NoxTLS 0.2.71 adds APIs that make TLS integration more controllable in event-driven and embedded applications, while preserving the strict protocol behavior introduced in 0.2.70:

  • Caller-polled, nonblocking TLS record I/O and resumable TLS 1.2 handshakes.
  • TLS 1.3 session export/import for caller-owned resumption storage.
  • Unified TLS controls for CRLs, bounded plaintext record payloads, handshake progression, and connection inspection.
  • Detailed, non-secret ECDH/ECDHE failure provenance for field diagnostics.
  • Streaming and split-message Ed25519 verification APIs.
  • Build fixes for strict compilers, duplicate CMAC implementation removal, and CMake-controlled Ed448 enablement.

Security Impact​

What Improved​

  • Bounded nonblocking output: encrypted output accepted by the record layer is queued only up to NOXTLS_TLS_IO_TX_QUEUE_LIMIT (256 KiB by default). This prevents an indefinitely blocked transport from causing unbounded queued output.
  • Explicit I/O progress states: callers can distinguish an incomplete read (NOXTLS_RETURN_WANT_READ) from pending encrypted output (NOXTLS_RETURN_WANT_WRITE) and resume without re-encrypting application data.
  • Mutual-auth policy: TLS 1.2 servers can require a non-empty client certificate instead of accepting an empty Certificate message after requesting client authentication.
  • Diagnostic safety: ECDH diagnostics expose only the failing control-flow stage and internal status—not private scalars, points, or shared-secret bytes.
  • CRL and record-size policy: the unified API can apply a CRL chain consistently and request bounded record payloads using the protocol-appropriate extension.

Default-Risk Posture Change​

  • Blocking I/O remains the default. Caller-polled behavior is opt-in through TLS_IO_MODE_NON_BLOCKING.
  • The default nonblocking transmit-queue limit is finite. Applications that need a different bounded limit must configure it explicitly.
  • Existing permissive client-auth behavior remains available when the server requests, but does not require, a client certificate.

Compatibility Notes​

  • The new APIs are additive; existing blocking connect(), accept(), send(), and recv() integrations keep their established behavior.
  • A nonblocking transport callback must return TLS_IO_WOULD_BLOCK when it cannot make progress. Applications must treat NOXTLS_RETURN_WANT_READ and NOXTLS_RETURN_WANT_WRITE as resumable, not terminal, results.
  • TLS 1.3 session export objects contain resumption PSK material. Store them as sensitive data, bind them to the intended peer policy, and erase them when no longer needed.

Protocol and Crypto Changes​

Caller-Polled TLS and Resumption​

  • Added caller-polled record transport support, including partial-record reassembly, partial-write retention, explicit flushing, and an encrypted-output queue limit.
  • Added noxtls_tls12_connect_poll() and noxtls_tls12_accept_poll() for resumable TLS 1.2 handshakes.
  • Added noxtls_tls13_session_export() and noxtls_tls13_session_import() so client resumption state can be stored outside the connection context and installed before ClientHello.
  • Added unified handshake progression with noxtls_tls_connection_handshake() plus output flushing and pending-output inspection.

Unified TLS Security and Observability​

  • Added unified setters for CRL verification, maximum plaintext record payload, I/O mode, transmit-queue limit, and imported TLS 1.3 session state.
  • Added accessors for the authenticated peer leaf certificate, negotiated cipher suite, resumption status, issued session identity, and resumption identity.
  • Added TLS 1.2 required-client-auth policy support.

ECDH Diagnostics​

  • Added noxtls_ecdh_compute_shared_secret_ex() and noxtls_ecdh_diagnostic_t for optional, non-secret failure provenance.
  • TLS ECDHE now propagates specific ECDH return codes and retains the most recent diagnostic in tls_ecdhe_context_t.

Ed25519 Streaming Verification​

  • Added noxtls_ed25519_verify_stream_init(), noxtls_ed25519_verify_stream_update(), and noxtls_ed25519_verify_stream_final() for verification without staging a complete message in memory.
  • Added noxtls_ed25519_verify_split() for a two-segment message.
  • Corrected the streaming-finalization implementation to use the existing non-failing point helpers correctly on strict C compilers.

Build and Configuration​

  • Removed a duplicate AES-CMAC streaming implementation that could cause strict-build conflicts.
  • Resolved strict-build merge regressions in the TLS implementation.
  • NOXTLS_FEATURE_ED448 now honors a compiler/CMake definition instead of unconditionally redefining the default in noxtls_config.h.

Operational Impact for Integrators​

  • Exercise the nonblocking path with fragmented receives, short writes, and writable-notification retries; call flush() after WANT_WRITE.
  • Validate session-cache protection and peer-policy binding before persisting TLS 1.3 resumption data.
  • Test required-client-auth behavior with both populated and empty client Certificate messages.
  • If ECDHE diagnostics are logged, ensure telemetry records only the documented enum/status fields and not application-owned key material.

Performance/Footprint Expectations​

  • Caller-polled I/O retains incomplete records and encrypted output in the connection context. Size the queue limit according to the memory budget and transport backpressure policy.
  • Streaming Ed25519 verification reduces the need to hold a complete signed message in a contiguous application buffer.

Known Limitations / Open Items​

  • DTLS 1.3 interop hardening remains an active area (ongoing external-suite alignment work).
  • Caller-polled support is for stream TLS. DTLS retains its datagram and retransmission model.
  • Resumption-state persistence is application-managed; NoxTLS does not provide durable storage, anti-rollback storage, or cross-process cache synchronization.

Upgrade and Migration Notes​

  • Stage event-driven integrations first, then enable TLS_IO_MODE_NON_BLOCKING and migrate loops to the WANT_READ/WANT_WRITE contract.
  • Keep using blocking APIs if the transport already blocks reliably; no migration is required.
  • Include the new TLS, ECDH, and Ed25519 public symbols in ABI/API compatibility checks.

Complete Change Inventory (since v0.2.70)​

Non-merge commits included in the 0.2.71 line:

  1. a9576bb - feat: extend unified TLS security controls
  2. ea804ec - Harden caller-polled TLS record I/O
  3. 2bbe9f0 - tls: add polled TLS 1.2 and resumable sessions
  4. 652935b - Expose detailed ECDH failure results
  5. d369bd2 - fix(tls): propagate ECDHE failure diagnostics
  6. 56d5966 - fix(cmac): remove duplicate streaming implementation
  7. 7e78243 - fix(tls): resolve strict-build merge regressions
  8. d33beda - feat(ed25519): add streaming verification API
  9. 90e266e - fix(ed25519): compile streaming verification

Integrity and Disclosure Notes​

  • This release includes security hardening but does not currently publish CVE IDs in this note set.
  • For coordinated vulnerability reporting, use the security reporting process documented in the project docs.