Lib.rs

Unambiguously digest structured data

udigest provides utilities for unambiguous hashing the structured data. Structured data can be anything that implements Digestable trait:

• str, String, CStr, CString
• Integers: i8, i16, i32, i64, i128, u8, u16, u32, u64, u128, char
• Containers: Box, Arc, Rc, Cow, Option, Result
• Collections: arrays, slices, Vec, LinkedList, VecDeque, BTreeSet, BTreeMap

The trait is intentionally not implemented for certain types:

• HashMap, HashSet as they can not be traversed in determenistic order
• usize, isize as their byte size varies on differnet platforms

The Digestable trait can be implemented for the struct using a macro:

use udigest::{Tag, udigest};
use sha2::Sha256;

#[derive(udigest::Digestable)]
struct Person {
    name: String,
    job_title: String,
}
let alice = &Person {
    name: "Alice".into(),
    job_title: "cryptographer".into(),
};

let tag = Tag::<Sha256>::new("udigest.example");
let hash = udigest(tag, &alice);

The crate intentionally does not try to follow any existing standards for unambiguous encoding. The format for encoding was desingned specifically for udigest to provide a better usage experience in Rust. The details of encoding format can be found in encoding module.

Features

• std implements Digestable trait for types in standard library
• alloc implements Digestable trait for type in alloc crate
• derive enables Digestable proc macro