m_security 0.3.5

A native Rust cryptographic SDK for Flutter via FFI. AES-256-GCM, ChaCha20-Poly1305, BLAKE3, SHA-3, Argon2id, HKDF, streaming encryption, and encrypted virtual file system.

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

0.3.5 - 2026-04-10

Added

• Per-segment metadata: vault_write() and vault_write_stream() accept optional HashMap<String, String> metadata, encrypted within the index block. vault_read() returns SegmentReadResult { data, metadata }.
• Segment rename: vault_rename_segment(old_name, new_name) updates the index without re-encryption. WAL-protected for crash safety. DuplicateSegment error variant added.
• Index caching: in-memory dirty flag tracks index mutations. Read-only operations skip redundant index encryption/flush. New vault_flush() API for explicit durability control.
• Parallel reads: vault_read_parallel(handle, names) decrypts multiple segments concurrently via rayon + mmap zero-copy. Returns per-segment SegmentResult { name, data, error }.
• Dart VaultService wrappers: renameSegment(), flush(), readParallel(). Updated write()/writeStream() to accept optional metadata parameter. Updated read() to return SegmentReadResult.
• 15 Dart integration tests covering metadata (4), rename (4), flush (2), parallel read (3), and combined workflows (2).
• Rust test suite refactored from monolithic tests.rs into 13 focused modules. 407 total Rust tests.
• Example app: metadata input field, rename dialog, flush button, parallel read all button.

Changed

• VAULT_VERSION bumped 1 → 2 for backward-compatible metadata deserialization (v1 vaults return empty metadata).
• ARCHIVE_VERSION bumped 1 → 2 for metadata preservation in export/import (v1 archives import with empty metadata).
• vault_write_file now passes metadata through to vault_write_stream (was hardcoded to None).
• vault_close() flushes dirty index before releasing lock, with best-effort WAL checkpoint on error.

Security

• Metadata encrypted within the index block (AEAD with index key), not in the segment cipher — no plaintext leakage.
• OOM guards: MAX_METADATA_PAIRS (1024) and MAX_METADATA_BYTES (64 KB) enforced on both read and write paths.
• Parallel reads use immutable &VaultHandle — no shared mutable state between threads. Compile-time Sync assertion.
• Checked offset arithmetic in parallel mmap slicing (checked_add instead of bare +).
• Plaintext zeroized on all checksum failure paths in parallel reads.

Fixed

• Async error assertions in Dart rename tests changed from expect() to await expectLater().
• Example app evfs_test.dart updated for SegmentReadResult return type.

0.3.4 - 2026-04-05

Added

• Master key rotation via vault_rotate_key() — re-encrypts all vault data under a new key using atomic copy-to-new-vault + rename strategy. Crash recovery: stale .rotating file cleaned on vault_open().
• Vault export via vault_export() — produces a self-contained .mvex encrypted archive with BLAKE3 integrity trailer, ephemeral export key AEAD-wrapped with caller's wrapping key, and per-segment re-encryption.
• Vault import via vault_import() — reads .mvex archive, creates new vault re-encrypted under a local master key. Validates header, unwraps export key, verifies per-segment BLAKE3 checksums and trailer integrity.
• ImportFailed, ExportFailed, and KeyRotationFailed error variants in CryptoError.
• Dart VaultService.rotateKey(), VaultService.export(), and VaultService.importVault() static methods.
• 7 Dart integration tests for key management (rotation roundtrip, old key rejection, export-import roundtrip, wrong wrapping key, 1MB+ segment, multiple rotations, rotate-then-export-import).
• 26 Rust tests for key management (10 rotation + 7 export + 9 import).
• Example app Key Management section with Rotate Key, Export, and Import buttons.
• CI workflow pinned flutter_rust_bridge_codegen to v2.11.1 to match runtime dependency.

Security

• Old sub-keys zeroized immediately after rotation via ZeroizeOnDrop.
• Export wrapping uses AAD b"msec-export-key-wrap" for domain separation.
• Archive format authenticated: per-segment AAD (segment name) + BLAKE3 trailer covering all preceding bytes.
• vault_write plaintext wrapped in Zeroizing<Vec<u8>> — guarantees zeroization on all exit paths including encrypt_segment failure.
• Import hardened: u64 to usize safe cast via try_from (32-bit overflow protection), OOM guard in u64 arithmetic with saturating_add, .lock file cleanup in error paths, segment name validation (1-255 bytes), segment_count sanity bound (100K), unknown compression byte rejection.
• Atomic rename before lock release in rotation (closes race window).

Fixed

• unwrap() in archive.rs replaced with map_err() for clippy compliance.
• from_bytes errors remapped to ImportFailed at import call sites.
• Example app lint: replaced src/ imports with public m_security.dart re-exports.

0.3.3 - 2026-03-28

Added

• Zero-copy vault reads via memmap2 memory-mapped I/O — vault_read and vault_read_stream now slice directly into mapped file pages instead of allocating heap buffers with read_exact.
• VaultMmap wrapper with mlock() on unix to pin ciphertext pages in RAM and prevent swap-to-disk. Graceful fallback to heap reads when mmap fails (32-bit targets, low mlock limits).
• mmap invalidation/recreation after every vault mutation (write, delete, defrag, resize).
• ELF linker version script (ffi-exports.map) restricting Android/Linux .so dynamic symbol table to FRB FFI symbols only — hides #[no_mangle] symbols leaked by dependencies.
• build.rs for conditional version script application on Android/Linux cdylib builds.

Changed

• Switched all 50 FRB functions from SSE to CST+DCO codec via full_dep: true — Vec<u8> returns now use allo-isolate ExternalTypedData (pointer transfer, no memcpy) instead of SSE serialization.
• Release profile hardened: lto = "fat", codegen-units = 1, strip = "symbols", opt-level = 3.
• VaultHandle field order: mmap before file so munlock/munmap runs while the fd is still open.

Security

• Symbol stripping removes internal Rust function names from release binaries — nm -D shows only FRB entry points and libc on ELF targets.
• mlock() prevents OS from swapping mmap'd ciphertext pages to disk swap.
• Fewer intermediate Vec<u8> copies means shorter plaintext residency in memory.
• ZeroizeOnDrop behavior preserved — no regression from zero-copy refactoring.

0.3.2 - 2026-03-26

Added

• vault_write_stream() for constant-memory chunked segment writes — encrypts data in 64 KB chunks without loading the full segment into RAM.
• vault_read_stream() for chunked segment reads via StreamSink — delivers decrypted data as a stream of byte chunks.
• Per-chunk AEAD encryption with domain-separated nonce derivation (0x01 prefix, chunk index, generation) — provably disjoint from monolithic nonce space.
• VaultChunkAad struct binding generation and chunk position to each chunk's authentication tag (cross-segment splice defense).
• vault_write_file() FRB-callable wrapper that reads a file in 64 KB chunks and pipes into vault_write_stream.
• Dart VaultService.writeStream() — accepts a Stream<Uint8List>, buffers to a temp file, and delegates to Rust for bounded-memory encryption.
• Dart VaultService.readStream() — returns a Stream<Uint8List> of decrypted chunks with optional onProgress callback.
• Streaming interop: segments written via streaming can be read one-shot (and vice versa).
• Integration tests for streaming: 10 MB roundtrip, write/read interop, progress reporting, error handling, and 50 MB memory-bounded validation.
• Example app streaming I/O section in the Vault tab — stream-write and stream-read with configurable size and live progress bar.

Fixed

• Checked arithmetic in decrypt_streaming_chunks read path — prevents wrong-region reads from crafted chunk counts.
• I/O errors in vault_write_file now surface as CryptoError::IoError instead of a misleading "stream underflow" message.
• total_received accumulation uses checked_add to prevent silent overflow on pathological input.
• Per-chunk fsync replaced with a single post-loop durability barrier — reduces streaming write I/O from O(N) fsyncs to O(1).
• WAL checkpoint after streaming write commit — prevents unbounded WAL growth.
• readStream cancellation leak — onCancel handler now cleans up data and progress subscriptions.
• Overflow error message now reports exact byte count, chunk size, and offset for easier debugging.

0.3.1 - 2026-03-16

Added

• Vault defragmentation: vault_defragment() compacts segments toward data region start, coalescing all free space with per-move WAL protection and post-commit secure erase.
• Vault resize: vault_resize() grows or shrinks vault capacity, relocating shadow index and WAL region.
• Vault health check: vault_health() returns VaultHealthInfo with fragmentation %, free region count, largest contiguous block, and consistency invariant.
• Dynamic index sizing: compute_index_size(capacity) scales segment index proportionally (64 KB per MB, min 64 KB, max 16 MB cap) — replaces fixed 64 KB INDEX_PAD_SIZE.
• Dart VaultService.defragment(), VaultService.resize(), and VaultService.health() wrappers with integration tests.
• Example app vault maintenance UI (defrag, resize, health).

Fixed

• Nonce reuse prevention after WAL recovery by hardening defrag backup path.
• Resize and defrag crash recovery hardening (fsync ordering, OOM guard, bounds check, health invariant overflow-safe check).
• Segment index size now scales with vault capacity — fixes OOM on large vaults with fixed 64 KB index.
• pub.dev score improvements.

Security

• No new information leaks, index_size remains deterministic from file size.
• Enforced index size bounds (64KB-16MB).
• Added safeguards against excessive memory usage.
• Header tampering results in authentication failure (no data exposure).

0.3.0 - 2026-03-07

Added

• Streaming encryption and decryption with chunk-based AES-256-GCM and ChaCha20-Poly1305, including progress callbacks for large file processing.
• Zstd and Brotli compression with configurable levels, integrated into both the streaming pipeline and the EVFS.
• Encrypted Virtual File System (EVFS): a .vault container supporting named segments, WAL crash recovery, shadow index, capacity management, and secure deletion.
• Full-featured Flutter example app demonstrating all library APIs (hashing, encryption, KDF, streaming, compression, vault).

Fixed

• Integration test reliability improvements for async race conditions and matcher corrections.

0.1.1 - 2026-03-06

Fixed

• Published package was missing rust/src/frb_generated.rs, which caused Rust compilation to fail for consumers.

0.1.0 - 2026-03-06

Initial release of M-Security, a native Rust cryptographic SDK for Flutter.

Added

• AES-256-GCM authenticated encryption with 32-byte keys, 12-byte auto-generated nonces, and 16-byte authentication tags.
• ChaCha20-Poly1305 authenticated encryption optimized for mobile processors lacking dedicated AES hardware.
• Unified CipherHandle interface for both ciphers (create, encrypt, decrypt, generate key). Output format: nonce || ciphertext || tag.
• BLAKE3 hashing with one-shot and streaming APIs via HasherHandle.
• SHA-3-256 (Keccak) hashing with one-shot and streaming APIs.
• Argon2id password hashing with Mobile (64 MiB, t=3, p=4) and Desktop (256 MiB, t=4, p=8) presets, automatic salt generation, and PHC string output.
• HKDF-SHA256 key derivation (RFC 5869) with derive, extract, and expand operations. Output range: 1-8160 bytes.
• Secure memory management with ZeroizeOnDrop on all key-holding structs.
• Opaque #[frb(opaque)] handles ensuring raw keys never cross the FFI boundary.
• Internal nonce generation via OsRng; callers never handle nonces.
• CI pipeline with Rust linting/testing, Dart analysis, and platform builds (Android, iOS, Linux).
• Integration tests for all cryptographic operations.
• Platform support: Android (ARM64, ARM32), iOS (ARM64, Simulator), macOS (ARM64, Intel), Linux (x86_64), Windows (x86_64).