hashes

You're right that an application project (a `binary crate` in Rust parlance) for embedded firmware versus a PC application is very different. But library crates are often usable in both an embedded or system-level context or in a full-fledged desktop GUI application. Consider these common libraries you might use in either a `std` project (PC application, web microservice) or `no_std` project (embedded microcontroller firmware, bootloader, Linux kernel module, blockchain smart contract): - data encoding (https://crates.io/crates/base64 for instance), - hashing (SHA2 https://github.com/RustCrypto/hashes/tree/master/sha2), - data structures (https://github.com/Lokathor/tinyvec) - time/date manipulation (https://docs.rs/chrono/latest/chrono/)

We were looking at the main branch of the sha2 crate at first, where the 'asm' feature has been removed (but this is unreleased, will be in 0.11.x) https://github.com/RustCrypto/hashes/blob/master/sha2/CHANGE...

Rust doesn't have varargs, so formatting functions tend to be macros (allowing to pass in multiple arguments, compile time parsing the format string to allow type checking etc) so they are generally not that trivial. There are some examples of printing output using formatting strings in the RustCrypto readme: let hash = Blake2b::digest(b"my message"); println!("Result: {:x}", hash); https://github.com/RustCrypto/hashes#usage If you're looking to get the actual string value rather than just print it out, then take a look at the format macro. It uses the same format strings / traits etc as println, so wherever you see println you could drop in format instead: let hash = Blake2b::digest(b"my message"); let text = format!("{:x}", hash); https://doc.rust-lang.org/std/macro.format.html