Pure Rust implementation of Base64 ([RFC 4648]).
Implements multiple Base64 variants without data-dependent branches or lookup tables, thereby providing portable "best effort" constant-time operation.
Supports no_std environments and avoids heap allocations in the core API
(but also provides optional alloc support for convenience).
This crate implements several Base64 variants in constant-time for sidechannel resistance, aimed at purposes like encoding/decoding the "PEM" format used to store things like cryptographic private keys.
The paper Util::Lookup: Exploiting key decoding in cryptographic libraries demonstrates how the leakage from non-constant-time Base64 parsers can be used to practically extract RSA private keys from SGX enclaves.
The padded variants require (=) padding. Unpadded variants expressly
reject such padding.
Whitespace is expressly disallowed.
[A-Z], [a-z], [0-9], +, /[A-Z], [a-z], [0-9], -, _., /, [A-Z], [a-z], [0-9]crypt(3) Base64: ., -, [0-9], [A-Z], [a-z]This crate requires Rust 1.56 at a minimum.
We may change the MSRV in the future, but it will be accompanied by a minor version bump.
Licensed under either of:
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.