# [RustCrypto]: Constant-Time Base16 (hexadecimal)[![crate][crate-image]][crate-link][![Docs][docs-image]][docs-link][![Build Status][build-image]][build-link]![Apache2/MIT licensed][license-image]![Rust Version][rustc-image][![Project Chat][chat-image]][chat-link]Pure Rust implementation of Base16 ([RFC 4648]).Implements lower and upper case Base16 variants without data-dependent branchesor lookup  tables, thereby providing portable "best effort" constant-timeoperation.Supports `no_std` environments and avoids heap allocations in the core API(but also provides optional `alloc` support for convenience).[Documentation][docs-link]## Minimum Supported Rust VersionThis crate requires **Rust 1.60** at a minimum.We may change the MSRV in the future, but it will be accompanied by a minorversion bump.## LicenseLicensed under either of: * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0) * [MIT license](http://opensource.org/licenses/MIT)at your option.### ContributionUnless you explicitly state otherwise, any contribution intentionally submittedfor inclusion in the work by you, as defined in the Apache-2.0 license, shall bedual licensed as above, without any additional terms or conditions.[//]: # (badges)[crate-image]: https://buildstats.info/crate/base16ct[crate-link]: https://crates.io/crates/base16ct[docs-image]: https://docs.rs/base16ct/badge.svg[docs-link]: https://docs.rs/base16ct/[build-image]: https://github.com/RustCrypto/formats/actions/workflows/base16ct.yml/badge.svg[build-link]: https://github.com/RustCrypto/formats/actions/workflows/base16ct.yml[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg[rustc-image]: https://img.shields.io/badge/rustc-1.60+-blue.svg[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/300570-formats[//]: # (links)[RustCrypto]: https://github.com/rustcrypto[RFC 4648]: https://tools.ietf.org/html/rfc4648[Util::Lookup]: https://arxiv.org/pdf/2108.04600.pdf