#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

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

#72 in Encoding

Download history 4784/week @ 2021-02-24 5425/week @ 2021-03-03 6779/week @ 2021-03-10 6644/week @ 2021-03-17 8396/week @ 2021-03-24 7157/week @ 2021-03-31 9698/week @ 2021-04-07 8128/week @ 2021-04-14 7760/week @ 2021-04-21 9677/week @ 2021-04-28 7726/week @ 2021-05-05 6956/week @ 2021-05-12 8313/week @ 2021-05-19 5818/week @ 2021-05-26 7685/week @ 2021-06-02 7061/week @ 2021-06-09

31,066 downloads per month
Used in 50 crates (20 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.