#base64 #bech32 #constant-time #hex #security

no-std subtle-encoding

Encoders and decoders for common data encodings (base64, bech32, hex) which avoid data-dependent branching/table lookups and therefore provide “best effort” constant time. Useful for encoding/decoding secret values such as cryptographic keys.

12 releases

✓ Uses Rust 2018 edition

0.5.1 Feb 8, 2020
0.5.0 Oct 14, 2019
0.4.1 Oct 7, 2019
0.3.7 Jun 5, 2019
0.3.0 Nov 25, 2018

#42 in Encoding

Download history 738/week @ 2019-11-01 853/week @ 2019-11-08 732/week @ 2019-11-15 865/week @ 2019-11-22 2239/week @ 2019-11-29 2041/week @ 2019-12-06 2281/week @ 2019-12-13 877/week @ 2019-12-20 1100/week @ 2019-12-27 1846/week @ 2020-01-03 1719/week @ 2020-01-10 1521/week @ 2020-01-17 2265/week @ 2020-01-24 2261/week @ 2020-01-31 1978/week @ 2020-02-07

6,918 downloads per month
Used in 12 crates (8 directly)

Apache-2.0 OR MIT


subtle-encoding iqlusion

Crate Docs Apache 2.0/MIT Licensed MSRV Safety Dance Build Status Gitter Chat

Rust crate for encoding/decoding binary data to/from base64 and hex encodings while avoiding data-dependent branching/table lookups, and therefore providing "best effort" constant-time operation.

Also includes a non-constant-time Bech32 encoder/decoder gated under the bech32-preview Cargo feature (with a goal of eventually making it constant-time).

Useful for encoding/decoding secret values such as cryptographic keys.


Minimum Supported Rust Version

  • Rust 1.39

Security Notice

While this crate takes care to avoid data-dependent branching, that does not actually make it "constant time", which is an architecture-dependent property.

This crate is a "best effort" attempt at providing a constant time encoding library, however it presently provides no guarantees, nor has it been independently audited for security vulnerabilities.

Use at your own risk.


Copyright © 2018-2020 iqlusion

subtle-encoding is distributed under the terms of either the MIT license or the Apache License (Version 2.0), at your option.

See LICENSE (Apache License, Version 2.0) file in the iqlusioninc/crates toplevel directory of this repository or LICENSE-MIT for details.