Easy Hex

An easy to use Hex-String formatting wrapper.

The goal of this library is to make it very easy to format or serialize any container of bytes as a hexadecimal string. This includes vectors, arrays, slices, etc. Example:

use easy_hex::Hex;

let hex = Hex([1, 16, 255]);
let json = serde_json::to_string(&hex).unwrap();
assert_eq!(json, r#""0110ff""#);

Features

• Compatible with every type that implements TryFrom<&[u8]> and AsRef<[u8]>.
• Flexible API, can be used with both owned and borrowed byte containers.
• Transparent type representation, allows freely casting between wrapper and wrapped type.
• Can wrap dynamically sized types.
• Supports lowercase and uppercase hex.
• Supports serde: Any byte container can be easily serialized as a hex string.
• Supports std formatting: Any byte container can be easily formatted as a hex string.
• Supports bytemuck: Allows safely casting between wrapper and wrapped type, and allows casting of references to the wrapper.

Supported Types

The API of this crate aims to support as many types as possible:

• Serialization is supported for all T: AsRef<[u8]>.
• Deserialization is supported for all T: TryFrom<&[u8]>.

This covers, among other things, these types:

• Vec<u8>
• [u8]
• [u8; N]
• Box<[u8]>
• &[u8]
• Other referenced types like &Vec<u8>
• Mutable referenced types like &mut [u8; N]
• Third Party types like GenericArray<u8, N> (Although this type currently only supports serialization, due to a missing TryFrom impl)

Note the explicit support of dynamically sized types like [u8]. They are possible because of the transparent representation:

use easy_hex::Hex;

let data: &[u8] = &[1, 2, 3];
let hex: &Hex<[u8]> = data.into();

Relevancy

There are many hex string formatting crates already, and this one does not aim to be better than any of them.

The main reason this exists is that the author wanted a reusable crate for hex string serialization with minimal boilerplate.

Performance

No particular performance benchmarks or optimizations have been applied to this crate so far. The properties of the implementation are:

• It reuses the encoding and decoding implementation of the hex crate.
• It uses a stack buffer for small hexstrings or byte sequences, but otherwise needs to allocate a temporary vector during transcoding.

More Examples

Serializing byte vectors as hex strings:

use easy_hex::Hex;
use serde_derive::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct Example {
    // With wrapper
    array: Hex<[u8; 16]>,
    // Without wrapper
    #[serde(with = "easy_hex::serde")]
    vec: Vec<u8>
}

Formatting bytes as hex:

use easy_hex::{Hex, HexExt};

let data: [u8; 4] = [222, 173, 190, 239];

// Format by creating a temporary `&Hex<[u8; N]>`
let out = format!("contents of data: {}", data.as_hex());
assert_eq!(out, "contents of data: deadbeef");

// Format by wrapping the data explicitly
let hex = Hex(data);
println!("display: {hex}");
println!("debug: {hex:?}");
println!("explicit lower: {hex:x}");
println!("explicit upper: {hex:X}");