base16 (hex) encoding for Rust.

This is a base16 (e.g. hexadecimal) encoding and decoding library which was initially written with an emphasis on performance.

The bulk of this was written before Rust added SIMD, and I haven't gotten around to adding that. When I wrote it, it was the fastest non-SIMD impl, but I haven't done any comparison recently.

Usage

Add base16 = "0.2" to Cargo.toml, then:

fn main() {
    let original_msg = "Foobar";
    let hex_string = base16::encode_lower(original_msg);
    assert_eq!(hex_string, "466f6f626172");
    let decoded = base16::decode(&hex_string).unwrap();
    assert_eq!(String::from_utf8(decoded).unwrap(), original_msg);
}

More usage examples in the docs.

no_std Usage

This crate supports use in no_std configurations using the following knobs.

• The "alloc" feature, which is on by default, adds a number of helpful functions
  that require use of the alloc crate,
  but not the rest of std. This is no_std compatible.
  • Each function documents if it requires use of the alloc feature.
• The "std" feature, which is not on by default, enables the "alloc" feature, and
  additionally makes base16::DecodeError implement the std::error::Error trait.

For clarity, this means that by default, we assume you are okay with use of the global allocator. This can be disabled as follows:

[dependencies]
base16 = { version = "0.2", default-features = false }

If you just want the core base16 functionality and none of the helpers, then you should turn off all features.

[dependencies]
# Turn of use of `std` and `alloc`.
base16 = { version = "0.2", default-features = false }

Both of these configurations are no_std compatible.

License

Public domain, as explained by the Unlicense. Alternatively, you can use either of the typical rusty MIT/Apache-2.0 combination.