1# [RustCrypto]: zeroize
2
3[![Crate][crate-image]][crate-link]
4[![Docs][docs-image]][docs-link]
5![Apache 2.0/MIT Licensed][license-image]
6![MSRV][rustc-image]
7[![Build Status][build-image]][build-link]
8
9Securely zero memory (a.k.a. [zeroize]) while avoiding compiler optimizations.
10
11This crate implements a portable approach to securely zeroing memory using
12techniques which guarantee they won't be "optimized away" by the compiler.
13
14The [`Zeroize` trait] is the crate's primary API.
15
16[Documentation]
17
18## About
19
20[Zeroing memory securely is hard] - compilers optimize for performance, and
21in doing so they love to "optimize away" unnecessary zeroing calls. There are
22many documented "tricks" to attempt to avoid these optimizations and ensure
23that a zeroing routine is performed reliably.
24
25This crate isn't about tricks: it uses [core::ptr::write_volatile]
26and [core::sync::atomic] memory fences to provide easy-to-use, portable
27zeroing behavior which works on all of Rust's core number types and slices
28thereof, implemented in pure Rust with no usage of FFI or assembly.
29
30- No insecure fallbacks!
31- No dependencies!
32- No FFI or inline assembly! **WASM friendly** (and tested)!
33- `#![no_std]` i.e. **embedded-friendly**!
34- No functionality besides securely zeroing memory!
35- (Optional) Custom derive support for zeroing complex structures
36
37## Minimum Supported Rust Version
38
39Rust **1.56** or newer.
40
41In the future, we reserve the right to change MSRV (i.e. MSRV is out-of-scope
42for this crate's SemVer guarantees), however when we do it will be accompanied by
43a minor version bump.
44
45## License
46
47Licensed under either of:
48
49* [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
50* [MIT license](http://opensource.org/licenses/MIT)
51
52at your option.
53
54### Contribution
55
56Unless you explicitly state otherwise, any contribution intentionally submitted
57for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
58dual licensed as above, without any additional terms or conditions.
59
60[//]: # (badges)
61
62[crate-image]: https://img.shields.io/crates/v/zeroize.svg
63[crate-link]: https://crates.io/crates/zeroize
64[docs-image]: https://docs.rs/zeroize/badge.svg
65[docs-link]: https://docs.rs/zeroize/
66[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
67[rustc-image]: https://img.shields.io/badge/rustc-1.56+-blue.svg
68[build-image]: https://github.com/RustCrypto/utils/actions/workflows/zeroize.yml/badge.svg
69[build-link]: https://github.com/RustCrypto/utils/actions/workflows/zeroize.yml
70
71[//]: # (general links)
72
73[RustCrypto]: https://github.com/RustCrypto
74[zeroize]: https://en.wikipedia.org/wiki/Zeroisation
75[`Zeroize` trait]: https://docs.rs/zeroize/latest/zeroize/trait.Zeroize.html
76[Documentation]: https://docs.rs/zeroize/
77[Zeroing memory securely is hard]: http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
78[core::ptr::write_volatile]: https://doc.rust-lang.org/core/ptr/fn.write_volatile.html
79[core::sync::atomic]: https://doc.rust-lang.org/stable/core/sync/atomic/index.html
80[good cryptographic hygiene]: https://github.com/veorq/cryptocoding#clean-memory-of-secret-data
81