chore: add wasm32-unknown-unknown compatibility (#20)

* chore: add wasm32 conditional timing for Instant compatibility

* chore: add wasm32 fallback for AtomicU64 and SystemRandom

* chore: add RustCrypto aes-gcm backend for wasm32 encryption

ring doesn't compile on wasm32-unknown-unknown (requires clang for C asm).
Move ring to a target-conditional dep (native only), add aes-gcm from
RustCrypto for wasm32. Both produce identical AES-256-GCM wire format:
[nonce(12)][ciphertext][auth_tag(16)]

Native targets continue using ring for hardware-accelerated performance.
wasm32 targets use aes-gcm (pure Rust) when wasm+encryption features active.

key_derivation.rs unchanged — already uses RustCrypto hkdf/sha2, compiles
on both targets without modification.

* fix: resolve expert panel findings for wasm32 compat

- Fold aes-gcm/getrandom into encryption feature (no separate wasm flag needed)
- Enable zeroize on aes/aes-gcm deps (scrub round keys on drop)
- Add cross-backend wire format test (ring <-> aes-gcm roundtrip)
- Remove dead cfg guards inside native-only functions
- Consistency: error messages, min length expression, doc comments

* chore: apply cargo fmt

* chore: bump MSRV from 1.82 to 1.85

cbindgen 0.29.2 pulls clap 4.6.0 which requires edition2024
(stabilized in Rust 1.85, Feb 2025). Pinning transitive deps
is fragile; bumping MSRV is the correct fix.

* ci: update MSRV job from 1.82 to 1.85

* chore: update cargo-deny skips for getrandom version changes

aes-gcm brings in getrandom 0.2.x (via crypto-common), proptest
uses 0.3.x, and tempfile/cbindgen uses 0.4.x. Updated skip entries
to use semver ranges instead of exact versions.

Author: 27Bslash6

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         # Full OS matrix for stable only; MSRV and beta on ubuntu only
         include:
           # MSRV - ensures we don't use newer Rust features
-          - rust: "1.82"
+          - rust: "1.85"
             os: ubuntu-latest
           # Stable - primary target, all platforms
           - rust: stable
@@ -51,7 +51,7 @@ jobs:
         run: cargo fmt --check
 
       - name: Run clippy
-        if: matrix.rust != '1.82'
+        if: matrix.rust != '1.85'
         run: cargo clippy --all-features -- -D warnings
 
       - name: Run tests (all features)

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.1"
 edition = "2021"
 authors = ["cachekit Contributors"]
 description = "LZ4 compression, xxHash3 integrity, AES-256-GCM encryption for byte payloads"
-rust-version = "1.82"
+rust-version = "1.85"
 license = "MIT"
 repository = "https://github.com/cachekit-io/cachekit-core"
 homepage = "https://github.com/cachekit-io/cachekit-core"
@@ -36,20 +36,32 @@ lz4_flex = { version = "0.11", features = ["frame", "std"], optional = true }
 # xxHash3-64: ~36 GB/s, sufficient for corruption detection (security via AES-GCM auth tag)
 xxhash-rust = { version = "0.8", features = ["xxh3"], optional = true }
 
-
 # Encryption dependencies (all optional, gated by encryption feature)
 # Uses HKDF-SHA256 for key derivation (NOT Blake2b - that's only for Python cache keys)
-ring = { version = "0.17", optional = true }
+# ring is native-only (see [target.'cfg(not(target_arch = "wasm32"))'.dependencies])
 zeroize = { version = "1.8", features = ["derive"], optional = true }
 hkdf = { version = "0.12", optional = true }
 sha2 = { version = "0.10", optional = true }
 hmac = { version = "0.12", optional = true }
 generic-array = { version = "0.14", optional = true }
 
+# wasm32 RNG: getrandom with JS feature for wasm32-unknown-unknown targets
+getrandom = { version = "0.2", features = ["js"], optional = true }
+
+# RustCrypto: pure-Rust AES-256-GCM for wasm32 targets (ring requires clang + C asm)
+aes-gcm = { version = "0.10", features = ["zeroize"], optional = true }
+aes = { version = "0.8", features = ["zeroize"], optional = true }
+
 # Byte utilities
 bytes = "1.5"
 byteorder = "1.5"
 
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+# ring: hardware-accelerated AES-256-GCM for native targets only.
+# Does NOT compile on wasm32-unknown-unknown (requires clang for C asm).
+# Kept optional so it is only compiled when the `encryption` feature is active.
+ring = { version = "0.17", optional = true }
+
 [build-dependencies]
 # C header generation (required for ffi feature)
 cbindgen = "0.29"
@@ -59,6 +71,7 @@ proptest = "1.4"
 serde_json = "1.0"
 blake2 = "0.10"
 hex = "0.4"
+aes-gcm = { version = "0.10", features = ["zeroize"] }
 
 [features]
 default = ["compression", "checksum", "messagepack"]
@@ -69,18 +82,28 @@ checksum = ["dep:xxhash-rust"]
 messagepack = ["dep:rmp-serde"]
 
 # Encryption (AES-256-GCM with HKDF-SHA256 key derivation)
+# Native: ring provides hardware-accelerated AES-256-GCM (target-conditional dep above)
+# wasm32: aes-gcm (pure Rust) is used instead — automatically selected via cfg(target_arch)
+# aes-gcm/aes/getrandom compile on native but are dead code (all usage behind wasm32 cfg);
+# the compiler optimizes them out.
 encryption = [
     "dep:ring",
     "dep:zeroize",
     "dep:hkdf",
     "dep:sha2",
     "dep:hmac",
     "dep:generic-array",
+    "dep:aes-gcm",
+    "dep:aes",
+    "dep:getrandom",
 ]
 
 # C FFI layer (generates include/cachekit.h)
 ffi = []
 
+# wasm32 support: alias for encryption (deps now folded into encryption feature)
+wasm = ["encryption"]
+
 # Kani formal verification configuration
 # Provides mathematical proofs of memory safety for unsafe code and FFI boundaries
 [package.metadata.kani]

deny.toml

@@ -70,8 +70,16 @@ deny = []
 # Skip specific dependencies from multiple-version checks
 # These are transitive dependencies where version duplication is unavoidable
 skip = [
-    # getrandom 0.2.x via ring, getrandom 0.3.x via proptest/tempfile
-    { crate = "getrandom@0.2.16", reason = "Transitive via ring crypto lib" },
+    # getrandom has 3 major versions in the dep tree:
+    # 0.2.x via aes-gcm/crypto-common (encryption)
+    # 0.3.x via proptest (dev-dependency)
+    # 0.4.x via tempfile/cbindgen (build-dependency)
+    { crate = "getrandom@0.2", reason = "Transitive via aes-gcm crypto chain" },
+    { crate = "getrandom@0.3", reason = "Transitive via proptest (dev-dependency)" },
+    # rand_core duplication from aes-gcm (0.6.x) vs proptest (0.9.x)
+    { crate = "rand_core@0.6", reason = "Transitive via aes-gcm crypto chain" },
+    # libc duplication unavoidable (getrandom versions pull different libc)
+    { crate = "libc@0.2", reason = "Transitive via multiple getrandom versions" },
 ]
 
 # Skip crate trees entirely (e.g., frequently-updated foundational crates)

src/byte_storage.rs

@@ -10,6 +10,7 @@ use crate::metrics::OperationMetrics;
 use lz4_flex;
 use serde::{Deserialize, Serialize};
 use std::sync::{Arc, Mutex};
+#[cfg(not(target_arch = "wasm32"))]
 use std::time::Instant;
 use thiserror::Error;
 #[cfg(feature = "checksum")]
@@ -175,14 +176,17 @@ impl ByteStorage {
 
         let format = format.unwrap_or_else(|| self.default_format.clone());
 
-        // Time compression operation
+        // Time compression operation (wasm32: Instant unavailable, use 0)
+        #[cfg(not(target_arch = "wasm32"))]
         let compression_start = Instant::now();
         let original_size = data.len();
 
         let envelope = StorageEnvelope::new(data.to_vec(), format)?;
 
-        let compression_elapsed = compression_start.elapsed();
-        let compression_micros = compression_elapsed.as_micros() as u64;
+        #[cfg(not(target_arch = "wasm32"))]
+        let compression_micros = compression_start.elapsed().as_micros() as u64;
+        #[cfg(target_arch = "wasm32")]
+        let compression_micros = 0u64;
         let compressed_size = envelope.compressed_data.len();
 
         // Serialize envelope with MessagePack
@@ -220,14 +224,17 @@ impl ByteStorage {
         let envelope: StorageEnvelope = rmp_serde::from_slice(envelope_bytes)
             .map_err(|e| ByteStorageError::DeserializationFailed(e.to_string()))?;
 
-        // Time decompression and checksum operations
+        // Time decompression and checksum operations (wasm32: Instant unavailable, use 0)
+        #[cfg(not(target_arch = "wasm32"))]
         let decompress_start = Instant::now();
 
         // Extract and validate data (all security checks happen inside extract())
         let data = envelope.extract()?;
 
-        let decompress_elapsed = decompress_start.elapsed();
-        let decompress_micros = decompress_elapsed.as_micros() as u64;
+        #[cfg(not(target_arch = "wasm32"))]
+        let decompress_micros = decompress_start.elapsed().as_micros() as u64;
+        #[cfg(target_arch = "wasm32")]
+        let decompress_micros = 0u64;
 
         // Calculate compression ratio from stored metadata
         let compressed_size = envelope.compressed_data.len();