Dependency-free, no_std-first secret memory sanitization for Rust.
Redacted secret containers, safe defaults, explicit volatile wiping, and optional derive ergonomics.

Docs.rs | Threat Model | Safety | Security

sanitization

Dependency-free, no_std-first secret memory sanitization for Rust.

sanitization is for projects that want a small secret-container layer without pulling in zeroize or a proc-macro dependency by default. The main design is architectural: keep secrets inside redacted, non-Copy, non-Clone, clear-on-drop containers from creation, and use explicit opt-in APIs when an ordinary buffer must be wiped. Every crate clearing path uses volatile writes by default through one audited internal unsafe boundary.

Current Status

The crate is published as stable 1.1.0 on crates.io. It is intended for projects that want dependency-free secret ownership and sanitization by default, with stronger platform hardening available through explicit feature flags.

Implemented now:

• no_std default build.
• zero runtime dependencies.
• zero external dependencies by default; the optional derive feature pulls in the sanitization-derive proc-macro sister crate.
• one audited internal unsafe boundary for default volatile clearing.
• explicit feature-gated unsafe modules for platform hardening, documented in SAFETY.md.
• SecretBytes<N> for fixed-size secrets.
• Secret<T> for custom sanitizable values.
• secure_sanitize_struct! and secure_drop_struct! helper macros.
• optional SecureSanitize and SecureSanitizeOnDrop derives through the derive feature.
• optional zeroize and subtle trait interop for projects that already use RustCrypto ecosystem bounds.
• optional serde deserialization for loading secrets from config formats, with redacted serialization.
• optional alloc support with SecretVec and SecretString.
• optional platform memory locking with LockedSecretBytes<N> on supported Linux, Android, macOS, iOS, Windows, and BSD targets, plus a documented volatile-only WASM compatibility backend behind wasm-compat.
• optional dynamic locked byte storage with LockedSecretVec on supported native memory-lock targets.
• optional pooled locked-memory arenas with SecretPool<N, SLOTS> for many same-size fixed secrets under one memory-lock operation on native backends, plus the same pool API on WASM behind wasm-compat without host memory locking.
• optional locked, pooled, and guarded canary integrity checks with canary-check.
• optional OS-CSPRNG canary words with random-canary.
• optional x86_64 assembly-backed equal-length comparison.
• optional x86_64 volatile-clear plus cache-line eviction helpers.
• optional explicit multi-pass volatile clear helpers.
• optional SIMD/vector register scrubbing helpers on x86_64 and AArch64.
• optional hardware-backed secret provider traits for enclave, HSM, TEE, or platform-keystore integration crates.
• optional N-of-N XOR split storage with SplitSecretBytes<N, SHARES>.
• no-std fixed-size lifetime enforcement with caller-provided monotonic clocks.
• optional std lifetime enforcement with ExpiringSecretBytes<N>.
• optional guard-page dynamic byte storage with GuardedSecretVec on supported Linux, Android, macOS, iOS, Windows, and BSD targets.
• explicit volatile helper APIs for existing ordinary buffers.
• redacted Debug for secret-owning wrapper types.
• clear-on-drop behavior for crate-owned secret containers.
• local CI/check script and GitHub workflows.
• optional bounded Kani proof harnesses for core fixed-size properties.
• separate optional sanitization-arrayvec and sanitization-bytes wrapper crates for users that already depend on those ecosystems.
• threat model and unsafe-boundary documentation.

Trust Dashboard

Area	Status
License	MIT OR Apache-2.0
MSRV	Rust 1.90.0
Default target	no_std
Runtime dependencies	zero external crates by default
Unsafe policy	#![deny(unsafe_code)] at crate root, isolated #[allow(unsafe_code)] modules documented in SAFETY.md
Clear primitive	volatile writes by default
Heap support	alloc feature
Proc macros	optional derive feature via sanitization-derive
Formal verification	optional bounded Kani harnesses for core properties
Main guarantee	narrow ownership, redaction, and clear-on-drop hygiene
Out of scope	stack-history wiping, global cache secrecy, crash dumps, privileged reads

Read THREAT_MODEL.md and SAFETY.md before using this crate for high-assurance secret handling.

Read ROADMAP.md for the implemented architecture direction and remaining high-assurance feature work.

Rust Version Support

The minimum supported Rust version is Rust 1.90.0. New deployments should prefer the latest stable Rust.

Compatibility evidence:

Rust	Local Evidence
1.90.0	full check gate
1.91.0	cargo check --all-features
1.92.0	cargo check --all-features
1.93.0	cargo check --all-features
1.94.0	cargo check --all-features
1.95.0	cargo check --all-features
1.96.0	cargo check --all-features

Install

[dependencies]
sanitization = "1.1.0"

For heap-backed secret containers:

[dependencies]
sanitization = { version = "1.1.0", features = ["alloc"] }

The unsafe-wipe feature is kept as a no-op compatibility flag for older release-candidate dependency declarations. Volatile clearing is now the default.

For memory-locked fixed-size secrets on supported native platforms:

[dependencies]
sanitization = { version = "1.1.0", features = ["memory-lock"] }

For derive macros:

[dependencies]
sanitization = { version = "1.1.0", features = ["derive"] }

For optional ecosystem interop:

[dependencies]
sanitization = { version = "1.1.0", features = ["zeroize-interop", "subtle-interop"] }

For serde-based config loading:

[dependencies]
sanitization = { version = "1.1.0", features = ["serde", "alloc"] }

For optional ecosystem wrappers, depend on the separate sister crates only when you already use those external libraries:

[dependencies]
sanitization-arrayvec = "1.1.0"
sanitization-bytes = "1.1.0"

Features

Feature	Default	Purpose
alloc	no	Enables SecretVec and SecretString.
std	no	Enables alloc plus ExpiringSecretBytes<N> lifetime enforcement.
derive	no	Re-exports sanitization-derive proc macros for #[derive(SecureSanitize)] and #[derive(SecureSanitizeOnDrop)]. Pulls in proc-macro dependencies only when explicitly enabled.
serde	no	Implements serde deserialization for secret loading and redacted serialization for secret-owning wrappers.
zeroize-interop	no	Implements zeroize::Zeroize and zeroize::ZeroizeOnDrop for crate-owned secret containers.
subtle-interop	no	Implements subtle::ConstantTimeEq for byte-oriented secret containers where the subtle trait can represent the comparison.
memory-lock	no	Enables LockedSecretBytes<N>, native LockedSecretVec, SecretPool<N, SLOTS>, and locked guarded mappings on supported native targets. On WASM this must be paired with wasm-compat and exposes fixed-size volatile-only compatibility backends with no actual memory locking.
wasm-compat	no	Explicitly enables reduced-guarantee WASM compatibility backends for memory-lock APIs. This does not provide mlock, mprotect, dump exclusion, or guard pages.
canary-check	no	Enables memory-lock plus prefix/suffix canary checks for non-empty locked byte mappings, pooled slots, and guarded dynamic mappings. On WASM this must be paired with wasm-compat and random-canary.
random-canary	no	Enables canary-check and generates canary words from the OS CSPRNG instead of deriving them from mapping addresses. WASI preview1 uses random_get; other bare WASM targets report random generation failure. On WASM it also needs wasm-compat.
asm-compare	no	Uses an x86_64 inline-assembly loop for equal-length byte comparison.
cache-flush	no	Enables explicit x86_64 clear-and-cache-line-evict helpers.
register-scrub	no	Enables explicit best-effort SIMD/vector register scrubbing helpers on x86_64 and AArch64.
guard-pages	no	Enables GuardedSecretVec on supported Linux, Android, macOS, iOS, Windows, and BSD targets. This feature is rejected at compile time on WASM.
multi-pass-clear	no	Enables explicit three-pass volatile overwrite helpers for policy or audit compatibility.
hardware-secrets	no	Enables dependency-free traits for external hardware-backed secret provider crates.
split-secret	no	Enables SplitSecretBytes<N, SHARES> N-of-N XOR split storage.
unsafe-wipe	no	Compatibility no-op; volatile wiping is default.

Default builds are dependency-free and no_std.

WASM Support

The base containers (SecretBytes, Secret, ReadOnceSecret, and with alloc, SecretVec and SecretString) compile on wasm32 targets. memory-lock compiles on WASM only when wasm-compat is also enabled. That feature pair exposes API-compatible volatile-only backends: LockedSecretBytes<N> and SecretPool<N, SLOTS> own storage inside WASM linear memory and clear it on drop, but no mlock, mmap, mprotect, MADV_DONTDUMP, or page locking is applied because WASM modules cannot call those host-kernel facilities directly.

[dependencies]
sanitization = { version = "1.1.0", features = ["memory-lock", "wasm-compat"] }

memory-lock without wasm-compat is rejected at compile time on WASM so native memory-lock expectations are not silently degraded.

guard-pages is rejected at compile time on WASM. WASM linear memory has no per-page protection API available to the module, so a guard-page-less GuardedSecretVec would be misleading.

canary-check is also rejected at compile time on WASM unless wasm-compat and random-canary are enabled. Deterministic WASM canaries do not have ASLR-backed mapping entropy, so the crate requires a random canary backend instead of silently providing a predictable integrity word.

random-canary uses WASI preview1 random_get when targeting wasm32-wasip1. Bare wasm32-unknown-unknown, Emscripten-style WASM, and WASI preview2 currently return a Random operation error for random canary setup in this dependency-free implementation.

One caveat matters for all WASM targets: Rust volatile writes survive LLVM lowering to WASM, but the WASM specification has no volatile memory operation. The crate uses an #[inline(never)] function-pointer boundary on WASM as a best-effort barrier against runtime dead-store removal, but this is weaker than native volatile semantics. Treat WASM clearing as best-effort unless your runtime/deployment gives stronger guarantees, such as atomics/shared-memory support and a runtime that preserves those stores as observable effects.

Fixed-Size Secrets

Use SecretBytes<N> for keys, tokens, nonces, salts, or other fixed-size secret byte arrays that you control from creation.

use sanitization::SecretBytes;

let mut key = SecretBytes::<32>::from_fn(|index| index as u8);
let fallible_key =
    SecretBytes::<32>::try_from_fn(|index| Ok::<u8, &'static str>(index as u8)).unwrap();

assert_eq!(key.len(), 32);
assert_eq!(fallible_key.len(), 32);
assert!(key.constant_time_eq(&[
    0, 1, 2, 3, 4, 5, 6, 7,
    8, 9, 10, 11, 12, 13, 14, 15,
    16, 17, 18, 19, 20, 21, 22, 23,
    24, 25, 26, 27, 28, 29, 30, 31,
]));

key.replace_from_fn(|index| 31 - index as u8);
key.try_replace_from_fn(|index| Ok::<u8, &'static str>(index as u8))
    .unwrap();
key.replace_from_array([9; 32]);

key.transform(|bytes| {
    for byte in bytes.iter_mut() {
        *byte ^= 0xA5;
    }
});

let subkey = key.derive::<16>(|input, output| {
    output.copy_from_slice(&input[..16]);
});
assert_eq!(subkey.len(), 16);

key.into_cleared();

The type intentionally does not implement Clone, Copy, Deref, AsRef<[u8]>, or secret-printing Debug. SecretBytes<N> stores N bytes inline, and expose_secret creates an additional N-byte stack copy. On embedded targets or small thread stacks, choose N well below the available stack budget or use heap-backed containers. For key derivation, masking, or normalization logic that can operate inside the container, prefer transform, try_transform, derive, or try_derive so the operation does not need an extra expose_secret stack copy.

Expiring Secrets

Use MonotonicExpiringSecretBytes<N, C> when fixed-size secrets should reject access after a caller-defined number of monotonic ticks without requiring std:

use sanitization::{MonotonicClock, MonotonicExpiringSecretBytes};

struct CounterClock(u64);

impl MonotonicClock for CounterClock {
    fn now(&self) -> u64 {
        self.0
    }
}

let mut key =
    MonotonicExpiringSecretBytes::<32, _>::from_array([7; 32], CounterClock(10), 300);

assert_eq!(key.try_constant_time_eq(&[7; 32]), Ok(true));
assert_eq!(key.max_age_ticks(), 300);

The tick unit is application-defined: milliseconds, RTOS ticks, hardware counter increments, or another monotonic unit. The clock must not move backward within a secret lifetime window.

Enable std when you want the convenience wrapper backed by std::time::Instant:

[dependencies]
sanitization = { version = "1.1.0", features = ["std"] }

use sanitization::ExpiringSecretBytes;
use std::time::Duration;

let mut key = ExpiringSecretBytes::<32>::from_array([7; 32], Duration::from_secs(300));
let mut generated =
    ExpiringSecretBytes::<32>::try_from_fn(Duration::from_secs(300), |_| {
        Ok::<u8, &'static str>(7)
    })
    .unwrap();

assert_eq!(key.try_constant_time_eq(&[7; 32]), Ok(true));
assert_eq!(generated.try_constant_time_eq(&[7; 32]), Ok(true));

key.try_expose_secret(|bytes| {
    assert_eq!(bytes.len(), 32);
}).unwrap();
key.try_expose_secret_volatile(|bytes| {
    assert_eq!(bytes[0], 7);
}).unwrap();

key.replace_from_fn(|index| index as u8);
key.try_replace_from_fn(|index| Ok::<u8, &'static str>(index as u8))
    .unwrap();
key.into_cleared();

There is no background timer. Expiration is checked when a fallible access method is called. If the value has expired, the wrapped secret is cleared before returning SecretExpiredError. Full replacement with replace_from_slice, replace_from_fn, or try_replace_from_fn restarts the lifetime window for the new value. Fallible generated replacement keeps a still-live old value unchanged on generator error.

Copying Secrets Into External APIs

Some cryptographic or protocol APIs require &[u8]. Use expose_secret for short-lived closure access. The temporary copy is cleared on the normal return path and during unwinding, but cannot be cleared if the process aborts.

use sanitization::SecretBytes;

let key = SecretBytes::<32>::from_array([7; 32]);

let first_byte = key.expose_secret(|bytes| {
    // Call the external API here.
    bytes[0]
});

assert_eq!(first_byte, 7);

expose_secret_volatile is an explicit alias for callers that want the volatile-clearing behavior visible at the call site. Like expose_secret, it cannot clear the temporary stack copy if the process aborts.

use sanitization::SecretBytes;

let key = SecretBytes::<32>::from_array([7; 32]);
let first_byte = key.expose_secret_volatile(|bytes| bytes[0]);

assert_eq!(first_byte, 7);

Updating and Clearing Fixed-Size Secrets

Multi-byte mutation and clearing require &mut self, so shared references cannot observe partially-cleared multi-byte writes.

use sanitization::SecretBytes;

let mut key = SecretBytes::<32>::zeroed();

key.copy_from_slice(&[9; 32]).unwrap();
assert!(key.constant_time_eq(&[9; 32]));

key.write_byte(0, 1).unwrap();
assert_eq!(key.read_byte(0), Some(1));

key.secure_clear();
assert!(key.constant_time_eq(&[0; 32]));

Heap Secrets

Enable alloc for dynamic secret bytes and secret UTF-8 text.

use sanitization::{SecretString, SecretVec};

let mut token = SecretString::from_string(String::from("bearer-token"));
assert_eq!(token.try_with_secret(str::len), Ok(12));
assert!(token.constant_time_eq("bearer-token"));

let empty_text = SecretString::default();
assert!(empty_text.is_empty());

token.push_str("-v2");
assert_eq!(token.try_with_secret(|text| text.ends_with("-v2")), Ok(true));
token.try_with_secret_mut(|text| text.make_ascii_uppercase())
    .unwrap();
token.replace_from_secret_str("rotated-token");
token.replace_from_string(String::from("owned-token"));
token.replace_from_chars(5, |index| ['t', 'o', 'k', 'e', 'n'][index]);
token
    .try_replace_from_chars(5, |index| {
        Ok::<char, &'static str>(['t', 'o', 'k', 'e', 'n'][index])
    })
    .unwrap();

let mut bytes = SecretVec::from_vec(vec![115, 101, 115, 115, 105, 111, 110]);
bytes.extend_from_slice(b"-key");
assert_eq!(bytes.with_secret(|value| value.len()), 11);
assert!(bytes.capacity() >= bytes.len());
assert!(bytes.constant_time_eq(b"session-key"));

let empty_bytes = SecretVec::default();
assert!(empty_bytes.is_empty());

bytes.with_secret_mut(|value| value[0] = b'S');
bytes.replace_from_slice(b"rotated-session-key");
bytes.replace_from_vec(vec![1, 2, 3, 4]);
bytes.replace_from_fn(16, |index| index as u8);
bytes
    .try_replace_from_fn(16, |index| Ok::<u8, &'static str>(index as u8))
    .unwrap();

SecretVec and SecretString wipe initialized bytes and spare heap capacity before freeing their allocations. Use from_slice and from_secret_str when loading borrowed data. Use from_vec, from_string, replace_from_vec, and replace_from_string to take ownership of existing heap allocations without copying; those allocations become clear-on-drop secret storage. Use replace_from_slice and replace_from_secret_str when rotating from borrowed data. Use SecretVec::from_fn, try_from_fn, replace_from_fn, or try_replace_from_fn when dynamic bytes can be generated directly into clear-on-drop storage. Use SecretString::from_chars, try_from_chars, replace_from_chars, or try_replace_from_chars when secret UTF-8 text can be generated as char values. Fallible generation clears partial output on error. SecretString::try_with_secret_mut exposes mutable &mut str access without allowing safe Rust to invalidate UTF-8. They expose contents through closures and redact Debug. capacity() exposes allocation size metadata for callers that need to size append-heavy flows. Default creates an empty heap secret container.

Memory-Locked Secrets

Enable memory-lock for fixed-size secrets stored in private platform memory and locked with the operating system's resident-memory API on native targets. On WASM, pair memory-lock with wasm-compat to explicitly request API-compatible volatile-only storage without host memory locking.

Platform	Backend	Extra policy
Linux x86_64/aarch64	raw mmap/mlock syscalls	MADV_DONTDUMP and MADV_DONTFORK
Android	system mmap/mlock ABI	no crate-level dump/fork exclusion
macOS/iOS	system mmap/mlock ABI	no crate-level dump/fork exclusion
FreeBSD	system mmap/mlock ABI	MADV_NOCORE, no fork exclusion
OpenBSD/NetBSD/DragonFly BSD	system mmap/mlock ABI	no crate-level dump/fork exclusion
Windows	VirtualAlloc/VirtualLock	no crate-level dump/fork exclusion
WASM wasm32-*	inline WASM-owned storage	API compatibility only; no host memory lock, dump exclusion, or page protection

use sanitization::LockedSecretBytes;

let mut key = LockedSecretBytes::<32>::from_fn(|_| 7).unwrap();
let fallible_key =
    LockedSecretBytes::<32>::try_from_fn(|_| Ok::<u8, &'static str>(7)).unwrap();

assert!(key.constant_time_eq(&[7; 32]));
assert!(fallible_key.constant_time_eq(&[7; 32]));

key.with_secret(|bytes| {
    assert_eq!(bytes.len(), 32);
});

key.replace_from_slice(&[8; 32]).unwrap();
key.replace_from_array([9; 32]).unwrap();
key.replace_from_fn(|index| index as u8).unwrap();
key.try_replace_from_fn(|index| Ok::<u8, &'static str>(index as u8))
    .unwrap();

key.secure_clear();
assert!(key.constant_time_eq(&[0; 32]));
key.into_cleared();

LockedSecretBytes<N> does not use the Rust global allocator for the secret bytes. It creates a private platform mapping, applies platform hardening policy where supported by the backend, locks the mapping, volatile-clears the full mapping on drop, then unlocks and releases it. On WASM, there is no kernel mapping or memory-lock syscall available to the module. LockedSecretBytes<N> and SecretPool<N, SLOTS> therefore compile as volatile-only compatibility containers in WASM linear memory only when wasm-compat is enabled alongside memory-lock. This preserves API-level portability for shared code, but it does not prevent host-runtime copies, swapping, snapshots, browser memory inspection, or crash dumps. Use from_fn when bytes can be generated directly into locked or compatibility storage. Use try_from_fn for fallible generators such as RNG or KDF APIs. Use from_slice when loading bytes from an existing runtime buffer. from_array is still available for fixed arrays and clears its owned input array before returning. Use replace_from_array, replace_from_slice, replace_from_fn, or try_replace_from_fn when rotating the whole locked value. Array replacement clears its owned input array. Fallible generated replacement keeps the old locked value unchanged on generator error.

Use LockedSecretVec when the secret length is known only at runtime and you want native memory-locking without guard pages:

use sanitization::LockedSecretVec;

let mut token = LockedSecretVec::from_slice(b"session-key").unwrap();
let generated = LockedSecretVec::try_from_fn(11, |index| {
    Ok::<u8, &'static str>(b"session-key"[index])
})
.unwrap();

assert!(token.constant_time_eq(b"session-key"));
assert!(generated.constant_time_eq(b"session-key"));

token.extend_from_slice(b"-v2").unwrap();
token.replace_from_slice(b"rotated-session-key").unwrap();
token.replace_from_fn(16, |index| index as u8).unwrap();
token
    .try_replace_from_fn(16, |index| Ok::<u8, &'static str>(index as u8))
    .unwrap();

token.clear_secret();
assert!(token.is_empty());

LockedSecretVec uses the same native mapping and memory-lock backends as LockedSecretBytes<N>, but its payload length and capacity are dynamic. It is lower overhead than GuardedSecretVec because it does not reserve guard pages. Use GuardedSecretVec instead when page-boundary fault detection matters more than allocation footprint. LockedSecretVec is native-only; WASM has no host-kernel memory-lock facility and does not expose this dynamic locked type.

Enable canary-check when locked or guarded secrets should detect corruption that reaches either side of the secret data while staying inside the writable mapping or pooled slot.

[dependencies]
sanitization = { version = "1.1.0", features = ["canary-check"] }

use sanitization::LockedSecretBytes;

let key = LockedSecretBytes::<32>::from_array([7; 32]).unwrap();

let first = key
    .expose_secret_checked(|bytes| bytes[0])
    .unwrap();

assert_eq!(first, 7);
assert_eq!(key.constant_time_eq_checked(&[7; 32]), Ok(true));

With canary-check, non-empty LockedSecretBytes<N> mappings, LockedSecretVec mappings, and SecretPool<N, SLOTS> slots use this layout:

[ 8-byte canary ][ N-byte secret ][ 8-byte canary ]

Existing exposure APIs such as with_secret, copy_to_slice, and constant_time_eq verify the canaries before reading secret bytes. If corruption is detected, the full mapping or slot is volatile-cleared and those legacy APIs panic with a fixed message. Use expose_secret_checked, copy_to_slice_checked, constant_time_eq_checked, or verify_integrity on LockedSecretBytes<N>, expose_secret_checked, constant_time_eq_checked, or verify_integrity on LockedSecretVec and pool slots, when callers need explicit error handling with CanaryCorruptedError.

Canaries are derived from the mapping or slot address and a fixed mask on native mapped backends, so they require no RNG or dependency. That deterministic mode assumes ASLR or otherwise unpredictable mapping addresses and is best understood as blind-overwrite detection. If one deterministic canary value is disclosed, the expected value for that mapping or slot is recoverable because the mask is fixed; enable random-canary in ASLR-disabled, weak-ASLR, canary-disclosure, or compliance-sensitive environments. On WASM, canary-check requires random-canary because inline storage has no stable ASLR-backed mapping address. Canaries detect overwrites that reach the canary words; they do not detect corruption entirely inside the secret bytes, historical copies, or external copies. LockedSecretBytes<N>, LockedSecretVec, and live SecretPool slots rewrite canaries after secure_clear or clear_secret, so they remain reusable after manual clearing.

Enable random-canary when the canary word should come from the operating system CSPRNG instead of the deterministic address-derived fallback:

[dependencies]
sanitization = { version = "1.1.0", features = ["random-canary"] }

random-canary uses direct platform backends without additional crates: Linux and Android getrandom, macOS/iOS/BSD arc4random_buf, Windows BCryptGenRandom, and WASI preview1 random_get. On WASM, pair it with wasm-compat because random-canary enables the canary/memory-lock compatibility backend. Bare wasm32-unknown-unknown, Emscripten-style WASM, and WASI preview2 currently have no dependency-free crate-level random import here, so random-canary construction returns a Random operation error on those targets unless a future backend is added. If OS random generation fails during construction, locked and guarded constructors return a Random operation error. For pooled slots, use SecretPool::try_allocate when callers need explicit RNG error handling; legacy pool allocation helpers panic on RNG failure rather than silently falling back to deterministic canaries.

For many same-size locked secrets on native targets, use SecretPool<N, SLOTS> to amortize page-granule memory-locking overhead. This is useful on systems with small RLIMIT_MEMLOCK/VirtualLock quotas because one locked mapping can hold many slots. On WASM, SecretPool keeps the same allocation API only when wasm-compat is enabled, but stores slots in WASM linear memory and reports locked_len() == 0.

use sanitization::SecretPool;

let pool = SecretPool::<32, 64>::new().unwrap();

let mut first = pool.allocate_from_array([7; 32]).unwrap();
let second = pool.allocate_from_fn(|index| index as u8).unwrap();

assert_eq!(pool.capacity_slots(), 64);
assert!(first.constant_time_eq(&[7; 32]));
assert_eq!(second.with_secret(|bytes| bytes[0]), 0);

first.replace_from_slice(&[8; 32]).unwrap();
first.secure_clear();

drop(first); // clears this slot and returns it to the pool

On native targets, SecretPool<N, SLOTS> stores all slots inside one private locked mapping and tracks live slots with an atomic bitmap. On WASM with wasm-compat, the pool uses inline WASM-owned slot storage instead. A slot borrows the pool, so the pool cannot be dropped while slots are live. Dropping a slot volatile-clears that slot before marking it reusable. Dropping the pool volatile-clears the full native mapping before unlocking and releasing it, or clears all WASM-owned slots on WASM.

With canary-check, each non-empty pool slot has its own prefix and suffix canary. Slot exposure, copying, mutation, and comparison verify those canaries before accessing the payload. Checked slot APIs return CanaryCorruptedError; legacy APIs clear the slot and panic.

This feature is explicit because OS memory locking has platform limits. It can fail due to resource limits or policy. Linux MADV_DONTDUMP reduces ordinary Linux core-dump exposure and MADV_DONTFORK reduces accidental fork inheritance for the mapping. FreeBSD uses MADV_NOCORE for core-dump exclusion, but still does not provide fork exclusion. Other non-Linux backends currently only lock the pages and release them on drop. None of these APIs protect against all crash dump mechanisms, hibernation, debuggers, privileged process reads, DMA, malicious firmware, or copies made before data enters the locked container.

Guarded Heap Secrets

Enable guard-pages for dynamic byte secrets stored between inaccessible guard pages on supported Linux, Android, macOS, iOS, Windows, and BSD targets:

[dependencies]
sanitization = { version = "1.1.0", features = ["guard-pages"] }

use sanitization::GuardedSecretVec;

let mut token = GuardedSecretVec::from_slice(b"session-key").unwrap();
let generated = GuardedSecretVec::try_from_fn(11, |index| {
    Ok::<u8, &'static str>(b"session-key"[index])
})
.unwrap();

assert!(token.constant_time_eq(b"session-key"));
assert!(generated.constant_time_eq(b"session-key"));
token.extend_from_slice(b"-v2").unwrap();
assert_eq!(token.with_secret(|bytes| bytes.len()), 14);
token.replace_from_slice(b"rotated-session-key").unwrap();
token.replace_from_fn(16, |index| index as u8).unwrap();
token
    .try_replace_from_fn(16, |index| Ok::<u8, &'static str>(index as u8))
    .unwrap();

token.clear_secret();
assert!(token.is_empty());
token.into_cleared();

GuardedSecretVec uses a private platform mapping, leaves the pages before and after the writable data region inaccessible, volatile-clears the full writable region on drop, and then releases the allocation. It does not use the Rust global allocator for the secret bytes. Use GuardedSecretVec::from_fn when bytes can be generated directly into the guarded mapping; use try_from_fn for fallible generators. Use from_slice when loading bytes from an existing runtime buffer. Use replace_from_slice, replace_from_fn, or try_replace_from_fn when rotating or replacing the entire guarded value. Fallible generated replacement keeps the old value unchanged on generator error. Linux guarded mappings keep the no-libc page granules used by the raw syscall backend: 4 KiB on x86_64 and runtime AT_PAGESZ detection from /proc/self/auxv on aarch64, falling back to 64 KiB if detection fails. Android, macOS, iOS, and BSD use getpagesize; Windows uses GetSystemInfo.

With canary-check, GuardedSecretVec reserves an 8-byte canary before the initialized payload and another immediately after it. This catches in-region overwrites that guard pages cannot catch, such as writes that overrun the initialized length but stay inside the writable capacity. Exposure, mutation, growth, replacement, and comparison verify canaries first. Use expose_secret_checked, constant_time_eq_checked, or verify_integrity when callers need explicit CanaryCorruptedError handling.

When both guard-pages and memory-lock are enabled, guarded dynamic secrets can also lock their writable data pages:

[dependencies]
sanitization = { version = "1.1.0", features = ["guard-pages", "memory-lock"] }

use sanitization::GuardedSecretVec;

let token = GuardedSecretVec::locked_from_slice(b"session-key").unwrap();

assert!(token.is_memory_locked());
assert!(token.constant_time_eq(b"session-key"));

Locked guarded mappings preserve the lock state when they grow. Guard pages are not locked because they never contain secret bytes. On Linux, writable data pages are also marked with MADV_DONTDUMP and MADV_DONTFORK before locking; FreeBSD writable data pages are marked with MADV_NOCORE before locking. Other non-Linux backends currently lock the writable pages without crate-level dump or fork policy. Locking can fail due to OS resource limits or policy, and this does not change the broader memory-lock limits described above. GuardedSecretVec::locked_from_fn is available for direct byte generation after the writable data pages have been prepared and locked. Use locked_try_from_fn for fallible generation into locked guarded storage.

Guard pages are a fault-detection mechanism for crossing outside the mapped data pages. They do not catch logical overreads that stay inside the writable data capacity, and they do not protect external copies made before data enters the guarded container.

Custom Structs Without Proc Macros

Use secure_drop_struct! when the macro should own Drop and clear every field on drop:

use sanitization::{secure_drop_struct, SecretBytes};

secure_drop_struct! {
    struct SessionCredentials {
        private_key: SecretBytes<32>,
        nonce: SecretBytes<12>,
    }
}

let credentials = SessionCredentials {
    private_key: SecretBytes::from_array([1; 32]),
    nonce: SecretBytes::from_array([2; 12]),
};

assert!(credentials.private_key.constant_time_eq(&[1; 32]));

Use secure_sanitize_struct! when you need to write a custom Drop implementation yourself:

use sanitization::{secure_sanitize_struct, SecretBytes, SecureSanitize};

secure_sanitize_struct! {
    struct Credentials {
        private_key: SecretBytes<32>,
        nonce: SecretBytes<12>,
    }
}

let mut credentials = Credentials {
    private_key: SecretBytes::from_array([1; 32]),
    nonce: SecretBytes::from_array([2; 12]),
};

credentials.secure_sanitize();

These macros are declarative macro_rules! macros. They do not require syn, quote, proc-macro2, or any compile-time code-generation dependency. They currently support named-field structs without generics or where clauses.

Enable derive when you want full struct and enum derive support and accept the explicit proc-macro dependency tradeoff:

[dependencies]
sanitization = { version = "1.1.0", features = ["derive"] }

use sanitization::{SecretBytes, SecureSanitize, SecureSanitizeOnDrop};

#[derive(SecureSanitize, SecureSanitizeOnDrop)]
struct LoginCredentials {
    password: SecretBytes<32>,
    session_token: [u8; 32],
}

#[derive(SecureSanitize)]
enum KeyMaterial {
    Symmetric(SecretBytes<32>),
    Asymmetric {
        private: SecretBytes<64>,
        #[sanitization(skip)]
        public: [u8; 32],
    },
    Empty,
}

#[derive(SecureSanitize)] calls secure_sanitize on every non-skipped field. Every such field must implement SecureSanitize, so adding a new field without sanitization support becomes a compiler error. Use #[sanitization(skip)] only for fields that are intentionally non-secret or sanitized elsewhere.

The derive crate is a code generator only. It does not duplicate the wipe backend or secret containers; generated code calls this crate's SecureSanitize trait. Default builds do not depend on sanitization-derive, syn, quote, or proc-macro2.

Supported derive attributes are #[sanitization(skip)] on fields, #[sanitization(bound = "...")] on fields or containers for explicit generated where predicates, and #[sanitization(crate = "::path::to::sanitization")] on containers when the main crate is renamed in Cargo.toml. The helper attribute intentionally avoids the name sanitize, which collides with Rust's experimental built-in sanitizer attribute on nightly/Miri. Unions are rejected; implement them manually only when the active field invariant is documented.

For SecureSanitizeOnDrop on generic structs, put sanitization bounds on the struct declaration itself:

use sanitization::{SecureSanitize, SecureSanitizeOnDrop};

#[derive(SecureSanitize, SecureSanitizeOnDrop)]
struct Wrapper<T: SecureSanitize> {
    inner: T,
}

This is a Rust Drop restriction: the generated Drop impl cannot add a stricter T: SecureSanitize bound than the struct declaration.

Ecosystem Interop

The default build stays dependency-free. Enable interop features only when a downstream API already requires these ecosystem traits:

[dependencies]
sanitization = { version = "1.1.0", features = ["zeroize-interop", "subtle-interop"] }

use sanitization::SecretBytes;
use subtle::ConstantTimeEq;
use zeroize::Zeroize;

let mut key = SecretBytes::<32>::from_array([7; 32]);
let expected = SecretBytes::<32>::from_array([7; 32]);

assert_eq!(key.ct_eq(&expected).unwrap_u8(), 1);
key.zeroize();

zeroize-interop implements Zeroize and ZeroizeOnDrop for this crate's owned secret containers by routing to their existing clear methods. subtle-interop implements ConstantTimeEq for self-type comparisons where the subtle trait can represent the comparison. Slice and string comparisons remain available through this crate's native constant_time_eq methods.

Serde Loading

Enable serde when secrets need to be loaded from configuration formats. This feature deserializes into secret containers, but serialization always emits the literal redaction marker "<redacted>" so accidental config dumps or telemetry do not leak secret material.

[dependencies]
sanitization = { version = "1.1.0", features = ["serde", "alloc"] }
serde = { version = "1", features = ["derive"] }

use sanitization::{SecretBytes, SecretString};
use serde::Deserialize;

#[derive(Deserialize)]
struct Config {
    signing_key: SecretBytes<32>,
    api_token: SecretString,
}

This serde support is intentionally for ingestion. Do not rely on serde serialization to export or back up secrets; it redacts by design. For generic Secret<T> and ReadOnceSecret<T>, deserialization uses T's own Deserialize implementation, so use this crate's leaf types such as SecretBytes<N>, SecretVec, and SecretString at secret-bearing fields when you need secret-aware ingestion end to end.

Generic Secret Wrapper

Use Secret<T> when you already have a type that implements SecureSanitize and you want clear-on-drop plus redacted Debug.

use sanitization::{Secret, SecureSanitize};

#[derive(Default)]
struct Pair {
    left: [u8; 16],
    right: [u8; 16],
}

impl SecureSanitize for Pair {
    fn secure_sanitize(&mut self) {
        self.left.secure_sanitize();
        self.right.secure_sanitize();
    }
}

let mut pair = Secret::new(Pair {
    left: [1; 16],
    right: [2; 16],
});

pair.with_secret_mut(|value| value.left[0] = 9);

let mut empty_pair = Secret::<Pair>::default();
empty_pair.with_secret_mut(|value| value.right[0] = 7);

SecureSanitize is also implemented for common scalar and standard-library container shapes:

• integer types: u8 through u128, usize, signed integer equivalents, and isize.
• bool, char, f32, and f64.
• arrays and slices whose element type implements SecureSanitize.
• Option<T> and Result<T, E> when their contents implement SecureSanitize.
• with alloc: Box<T>, Vec<T>, and String.

use sanitization::{Secret, SecureSanitize};

let mut exponent = Secret::new(0xDEAD_BEEF_u64);
exponent.with_secret_mut(SecureSanitize::secure_sanitize);

let mut scalar_words = Secret::new([1_u64, 2, 3, 4]);
scalar_words.with_secret_mut(SecureSanitize::secure_sanitize);

let mut maybe_key = Secret::new(Some([7_u8; 32]));
maybe_key.with_secret_mut(SecureSanitize::secure_sanitize);

For Vec<T>, the generic implementation sanitizes initialized elements and then clears the vector. It does not wipe arbitrary spare capacity for every possible T, because spare capacity does not necessarily contain valid T values. For dynamic byte secrets where full allocation capacity matters, use SecretVec.

Opaque third-party numeric types such as BigUint cannot be implemented by this crate without taking a dependency on that type. Wrap them in a local newtype and implement SecureSanitize for the newtype, or convert the secret material into SecretBytes<N>/SecretVec at the boundary where possible.

Read-Once Secrets

Use ReadOnceSecret<T> when a value should be accessed once and then cleared. The consume methods take &self and atomically mark the wrapper as consumed, so repeated access through shared references returns AlreadyConsumedError.

use sanitization::{AlreadyConsumedError, ReadOnceSecret, SecretBytes};

let token = ReadOnceSecret::new(SecretBytes::<4>::from_array([1, 2, 3, 4]));

let sum = token.consume(|secret| {
    let mut out = [0; 4];
    secret.copy_to_slice(&mut out).unwrap();
    out.iter().copied().fold(0_u8, u8::wrapping_add)
}).unwrap();

assert_eq!(sum, 10);
assert_eq!(token.consume(|_| unreachable!()), Err(AlreadyConsumedError));

The wrapped value is cleared immediately after the first successful closure returns. If the closure unwinds, Drop clears during unwinding. Like all destructor-based cleanup, this cannot run if the process aborts.

Explicit Volatile Wiping

If a secret already lives in an ordinary buffer, call the volatile helper directly.

use sanitization::unsafe_wipe::volatile_sanitize_bytes;

let mut bytes = [0xA5; 32];
volatile_sanitize_bytes(&mut bytes);
assert_eq!(bytes, [0; 32]);

With alloc, Vec<u8> and String helpers are available:

use sanitization::unsafe_wipe::{volatile_sanitize_string, volatile_sanitize_vec};

let mut bytes = vec![0xBB; 16];
volatile_sanitize_vec(&mut bytes);
assert!(bytes.is_empty());

let mut token = String::from("secret-token");
volatile_sanitize_string(&mut token);
assert!(token.is_empty());

For clear-on-drop volatile behavior, use VolatileOnDrop:

use sanitization::unsafe_wipe::VolatileOnDrop;

let secret = VolatileOnDrop::new([1_u8, 2, 3, 4]);
assert_eq!(secret.with_secret(|bytes| bytes.len()), 4);

Multi-Pass Clearing

Enable multi-pass-clear when a policy requires explicit multi-pass overwrite evidence:

[dependencies]
sanitization = { version = "1.1.0", features = ["multi-pass-clear"] }

use sanitization::{sanitize_bytes_multi_pass, SecretBytes};

let mut bytes = [0xA5; 32];
sanitize_bytes_multi_pass(&mut bytes);
assert_eq!(bytes, [0; 32]);

let mut key = SecretBytes::<32>::from_array([7; 32]);
key.secure_clear_multi_pass();
assert!(key.constant_time_eq(&[0; 32]));

The pattern is zeros, then 0xFF, then zeros again, all through volatile writes. For ordinary volatile RAM, the default single-pass volatile zeroing is the normal security boundary; multi-pass clearing is provided for compliance language and audit compatibility, not because modern DRAM needs it.

Cache Flush Sanitization

Enable cache-flush on x86_64 when a call site explicitly needs volatile clearing followed by clflush/mfence over the affected cache lines:

[dependencies]
sanitization = { version = "1.1.0", features = ["cache-flush"] }

use sanitization::{cache_flush::cache_flush_sanitize_bytes, SecretBytes};

let mut scratch = [0xA5; 32];
cache_flush_sanitize_bytes(&mut scratch);
assert_eq!(scratch, [0; 32]);

let mut key = SecretBytes::<32>::from_array([7; 32]);
key.secure_clear_and_flush();
assert!(key.constant_time_eq(&[0; 32]));

With alloc, cache_flush_sanitize_vec and cache_flush_sanitize_string clear the full allocation capacity before flushing the allocation's cache lines. With both guard-pages and cache-flush, GuardedSecretVec also provides clear_secret_and_flush for its full writable data region. Unsupported targets, Miri, and builds without cache-flush do not expose the cache_flush module. This feature reduces post-clear cache residency; it does not protect against an attacker who can already observe cache timing while the secret is live.

Assembly Comparison

Enable asm-compare on x86_64 when you want equal-length secret comparisons to cross an explicit compiler boundary:

[dependencies]
sanitization = { version = "1.1.0", features = ["asm-compare"] }

The public API does not change. SecretBytes<N>, SecretVec, SecretString, and LockedSecretBytes<N> still use their normal constant_time_eq methods. Length mismatch remains public metadata and returns immediately. Unsupported targets, Miri, and builds without asm-compare use the portable Rust fallback. The portable fallback is designed to avoid data-dependent early exit, but it is not a formal hardware-level constant-time guarantee. Use asm-compare where it is available, or pair this crate with a dedicated constant-time comparison library when a protocol requires externally audited timing guarantees.

Register Scrubbing

Enable register-scrub when a call site explicitly wants a best-effort SIMD register clearing boundary after cryptographic code:

[dependencies]
sanitization = { version = "1.1.0", features = ["register-scrub"] }

use sanitization::register_scrub::scrub_simd_registers;

// Run crypto code that may use vector registers.
scrub_simd_registers();

On non-Windows x86_64 this uses vzeroall when AVX OS support is available, falling back to caller-saved XMM clears. On Windows x64 it clears XMM0-XMM5 and uses vzeroupper when AVX OS support is available, preserving ABI-required XMM6-XMM15 lower halves. On AArch64 this clears caller-saved V0-V7 and V16-V31. Unsupported targets expose a fenced no-op. This is not a whole-process register hygiene guarantee: it cannot clear compiler spills, callee-saved vector state, AVX-512 opmask registers, ZMM16-ZMM31, AArch64 V8-V15 upper halves, kernel context-switch buffers, registers used by other threads, or copies already written to memory.

Split Secrets

Enable split-secret for fixed-size N-of-N XOR split storage:

[dependencies]
sanitization = { version = "1.1.0", features = ["split-secret"] }

use sanitization::SplitSecretBytes;

let split = SplitSecretBytes::<32, 3>::from_array_with_generator([7; 32], |share, index| {
    // Documentation-only deterministic mask. Use a real CSPRNG or KDF-backed
    // random source in production.
    ((share as u8) << 4) ^ (index as u8)
})
.unwrap();

let reconstructed = split.reconstruct();
assert!(reconstructed.constant_time_eq(&[7; 32]));

This is not Shamir secret sharing and it is not threshold cryptography. Every share is required to reconstruct the secret. The generator closure must produce cryptographically random bytes for all mask shares; deterministic examples are only for documentation and tests. Debug builds reject trivially constant mask shares as a misuse guardrail, but this heuristic does not validate entropy.

Hardware Secret Traits

Enable hardware-secrets when an external crate needs a dependency-free trait surface for hardware-backed secret providers:

[dependencies]
sanitization = { version = "1.1.0", features = ["hardware-secrets"] }

use sanitization::hardware::{HardwareSecretHandle, HardwareSecretProvider};

struct Handle(u64);
impl HardwareSecretHandle for Handle {}

struct Provider;

impl HardwareSecretProvider for Provider {
    type Handle = Handle;
    type Error = ();

    fn seal_from_slice(&self, _secret: &[u8]) -> Result<Self::Handle, Self::Error> {
        Ok(Handle(1))
    }

    fn expose_secret<R, F: FnOnce(&[u8]) -> R>(
        &self,
        _handle: &Self::Handle,
        inspect: F,
    ) -> Result<R, Self::Error> {
        Ok(inspect(&[]))
    }

    fn rotate_from_slice(
        &self,
        _handle: &mut Self::Handle,
        _secret: &[u8],
    ) -> Result<(), Self::Error> {
        Ok(())
    }

    fn destroy(&self, _handle: Self::Handle) -> Result<(), Self::Error> {
        Ok(())
    }
}

The main crate does not include SGX, Nitro, TPM, HSM, or platform-keystore backends. Those belong in backend crates with their own platform dependencies, audits, and threat models.

Optional Integration Crates

The main sanitization crate remains dependency-free by default. The workspace also publishes small wrapper crates for users that already depend on common buffer libraries:

[dependencies]
sanitization-arrayvec = "1.1.0"
sanitization-bytes = "1.1.0"

use sanitization::SecretBytes;
use sanitization_arrayvec::SecretArrayVec;
use sanitization_bytes::SecretBytesMut;

let mut keys = SecretArrayVec::<SecretBytes<32>, 4>::new();
keys.push(SecretBytes::from_array([7; 32])).unwrap();

let mut token = SecretBytesMut::with_capacity(16);
token.extend_from_slice(b"session-token").unwrap();
token.extend_from_slice(b"-v2").unwrap();

keys.clear_secret();
token.clear_secret();

These crates use wrapper types because Rust's orphan rules prevent implementing SecureSanitize directly for external types in a separate crate. SecretBytesMut treats capacity as fixed after construction and returns an error instead of reallocating on append, because implicit BytesMut growth would free an old allocation containing secret bytes before it can be wiped. Allocate the maximum expected size up front with SecretBytesMut::with_capacity.

Choosing the Right API

Use case	Recommended API
Fixed-size key or token	SecretBytes<N>
Fixed-size key with no-std tick expiry	MonotonicExpiringSecretBytes<N, C>
Fixed-size key with access expiry	ExpiringSecretBytes<N> with std
Fixed-size key that should avoid swap/pagefiles on supported native platforms	LockedSecretBytes<N> with memory-lock
Dynamic bytes that should avoid swap/pagefiles on supported native platforms	LockedSecretVec with memory-lock
Fixed-size key needing API-compatible WASM storage	LockedSecretBytes<N> with memory-lock and wasm-compat on WASM, with documented reduced guarantees
Fixed-size locked key with prefix/suffix corruption checks	LockedSecretBytes<N> with canary-check
Fixed-size locked key with OS-random canary words	LockedSecretBytes<N> with random-canary
Many same-size fixed keys under native memory-lock quotas	SecretPool<N, SLOTS> with memory-lock
Many same-size fixed keys with pooled canary checks	SecretPool<N, SLOTS> with canary-check
Dynamic secret bytes	SecretVec with alloc
Dynamic bytes with platform guard pages	GuardedSecretVec with guard-pages
Guarded dynamic bytes with in-region corruption checks	GuardedSecretVec with guard-pages and canary-check
Secret UTF-8 text	SecretString with alloc
Secret scalar such as u64	Secret<u64>
Standard compound value	Secret<T> where T: SecureSanitize
One-time access secret	ReadOnceSecret<T>
Custom struct or enum with compiler-generated sanitization	#[derive(SecureSanitize)] with derive
Custom struct or enum with compiler-generated drop clearing	#[derive(SecureSanitize, SecureSanitizeOnDrop)] with derive
Custom struct, macro-owned drop	secure_drop_struct!
Custom struct, custom drop	secure_sanitize_struct!
Existing ordinary buffer	unsafe_wipe::volatile_sanitize_*
Generic clear-on-drop wrapper	Secret<T>
Explicit x86_64 comparison compiler boundary	asm-compare feature
Explicit x86_64 cache-line eviction after clearing	cache-flush feature
Explicit SIMD/vector register clearing boundary	register-scrub feature
N-of-N fixed-size split storage	SplitSecretBytes<N, SHARES> with split-secret
Hardware-backed backend crate integration	hardware-secrets feature traits
Existing RustCrypto APIs with zeroize or subtle bounds	zeroize-interop or subtle-interop features
Config-file secret ingestion	serde feature, with redacted serialization
arrayvec or bytes wrappers	sanitization-arrayvec or sanitization-bytes

Relationship to zeroize

zeroize is broader and more ergonomic for retrofitting existing types, especially with #[derive(Zeroize, ZeroizeOnDrop)]. This crate keeps the core crate dependency-free by default, but now offers an optional sanitization-derive sister crate behind the derive feature for users who want similar compiler-generated struct and enum coverage. When existing RustCrypto ecosystem APIs require zeroize or subtle trait bounds, enable zeroize-interop or subtle-interop; these are explicit opt-ins and are not part of the dependency-free default build.

The intended trade-off:

• use wrapper types from the start for stronger ownership discipline;
• keep default builds free of proc-macro dependencies;
• use dependency-free declarative macros for simple custom structs;
• enable derive when compiler-enforced field coverage is worth the explicit proc-macro dependency surface;
• use explicit volatile APIs only where ordinary memory must be wiped.

Local Checks

Run the local matrix before changing release-sensitive code:

bash scripts/checks.sh

The check script covers formatting, feature-matrix tests, examples, clippy, release LLVM IR/assembly verification, optional bounded Kani verification when cargo-kani is installed, docs with warnings denied, and package listing.

When a nightly toolchain with Miri is available, run the interpreter-based unsafe-boundary check separately:

scripts/verify-miri.sh

To run the bounded formal harnesses directly:

scripts/verify-kani.sh

These harnesses prove selected fixed-size properties for the volatile clearing path, secret clearing visibility, constant-time equality correctness, and capacity arithmetic. They are not a replacement for external review.

Workspace Layout

The repository is a multi-crate workspace:

crates/sanitization           # main dependency-free-by-default crate
crates/sanitization-derive    # optional proc-macro sister crate
crates/sanitization-arrayvec  # optional ArrayVec wrapper crate
crates/sanitization-bytes     # optional BytesMut wrapper crate

For crates.io releases, publish the derive crate first, then the main crate, then the integration wrapper crates:

scripts/release_1_1.py

The script runs the local checks, publishes in dependency order, and pauses after sanitization-derive and sanitization so crates.io can index each dependency before the dependent crate is published.

Manual order:

cd crates/sanitization-derive
cargo publish

cd ../sanitization
cargo publish

cd ../sanitization-arrayvec
cargo publish

cd ../sanitization-bytes
cargo publish

From the repository root, the equivalent package-specific commands are:

cargo publish -p sanitization-derive
cargo publish -p sanitization
cargo publish -p sanitization-arrayvec
cargo publish -p sanitization-bytes

Limits

This crate reduces accidental retention and accidental exposure. It does not provide complete process-memory secrecy.

Important limits:

• Volatile wiping requires the crate's internal wipe unsafe boundary; safe Rust alone cannot express volatile byte stores.
• Safe Rust cannot soundly scrub old stack frames from previous moves.
• panic = "abort" prevents destructors from running and prevents closure helpers from clearing temporary stack copies after a panic.
• Volatile writes prevent the intended clear operation from being optimized away, but cannot clear copies made elsewhere before data enters the container.
• CPU cache flushes, SIMD clearing, platform memory locking, guard pages, and inline assembly require target-specific unsafe code and are intentionally not part of the default API.
• It does not protect against swap, hibernation, core dumps, debugger access, /proc/<pid>/mem, kernel compromise, DMA, firmware compromise, or copies made by third-party libraries.

See THREAT_MODEL.md, SAFETY.md, and SECURITY.md for the security model and maintenance policy.