SecureBit.chat v4.8.5 — Security Hardening Release

This release consolidates several months of focused security, privacy, and lifecycle-hardening work by the SecureBit.chat team. It strengthens peer verification, narrows file-transfer risk, reduces local metadata exposure, and improves cleanup behavior across WebRTC sessions.

Security improvements

• Added mandatory interactive SAS verification; passive click-through confirmation is no longer sufficient.
• Made SAS computation deterministic across peers using shared session material.
• Enforced protocol version 4.1 mismatch handling for incompatible clients.
• Added TURN relay-only privacy mode for deployments that require protection from direct WebRTC IP exposure.
• Added clear warnings when TURN is unavailable and clarified that STUN alone does not provide IP privacy.
• Encrypted sensitive IndexedDB metadata, including timestamps and session-related fields where feasible.
• Added safe lazy migration for older plaintext metadata records.
• Added explicit consent gating for every incoming file transfer.
• Replaced broad file acceptance with a strict allowlist based on both MIME type and filename extension.
• Blocked executable, scriptable, and high-risk file types.
• Sanitized every incoming decrypted chat message before it reaches the UI.

Reliability and lifecycle improvements

• Consolidated disconnect behavior into a single canonical cleanup path.
• Improved cleanup of timers, deferred retries, peer-disconnect scheduling, fake traffic, and decoy channels.
• Ensured pending sender-side consent waits are cancelled immediately during cleanup.
• Added bounded retention for received-file buffers.
• Added graceful handling when old download handles refer to evicted buffers.
• Cleared React file-transfer UI state on disconnect and detached live callbacks on unmount.
• Improved reconnect hygiene and stale-session cleanup behavior.

Maintenance

• Pinned dependency versions.
• Applied safe transitive patch/minor updates.
• Verified a clean npm audit result.
• Expanded regression coverage across SAS verification, wrong-code lockout, file-transfer consent, file-type allowlist, incoming-message sanitization, TURN privacy mode, IndexedDB metadata encryption, disconnect cleanup, timer lifecycle, file-transfer cleanup, and UI callback cleanup.

Compatibility notes

• Product release: v4.8.5
• Protocol version: 4.1
• Older incompatible peers are rejected rather than silently downgraded.
• Relay-only privacy mode requires operator-provided TURN infrastructure.