Crate hex 

Fast hex encoding and decoding with SIMD acceleration, constant-time operations, and const fn support.

Encoding supports lowercase (0-9a-f) and uppercase (0-9A-F) alphabets via Alphabet. Decoding is case-insensitive.

Feature flags

Flag	Description
std	std::error::Error trait impls (enabled by default)
alloc	String/Vec-returning convenience APIs
serde	Serde serialize/deserialize helpers

Performance

The encode_into and decode_into functions automatically dispatch to SIMD-accelerated paths (AVX2 on x86/x86_64, NEON on aarch64). When a constant-time guarantee is required, use encode_into_constant_time or decode_into_constant_time.

const fn support

encode_array and decode_array are const fn, enabling hex encoding and decoding at compile time.

Examples

let encoded = hex::encode(b"hello");
assert_eq!(encoded, "68656c6c6f");

let decoded = hex::decode(b"68656c6c6f").unwrap();
assert_eq!(decoded, b"hello");

let upper = hex::encode_with_alphabet(b"hello", hex::Alphabet::Upper);
assert_eq!(upper, "68656C6C6F");

Enums

Alphabet

The hex character set used for encoding.

DecodeError

Errors that can occur during hex decoding.

EncodeError

Errors that can occur during hex encoding.

Functions

decodealloc

Decode Decodes a hex string into bytes.

decode_array

Decodes a hex string into a fixed-size array at compile time.

decode_into

Decodes a hex string into an existing buffer.

decode_into_constant_time

Constant-time hex decoding. Processes all input data without secret-dependent branches or memory accesses, making it suitable for cryptographic applications.

encodealloc

Encodes bytes to a lowercase hex string.

encode_array

Encodes data into a fixed-size array at compile time.

encode_into

Encodes bytes into an existing buffer.

encode_into_constant_time

Constant-time hex encoding. Processes all input data without secret-dependent branches or memory accesses, making it suitable for cryptographic applications.

encode_into_stringalloc

Appends the hex-encoded representation of data to a String.

encode_with_alphabetalloc

Encodes bytes to a hex string using the given Alphabet.