Crate dryoc 

dryoc: Don’t Roll Your Own Crypto™¹

dryoc is a pure-Rust, general-purpose cryptography library. It implements many libsodium-compatible APIs and wire formats, so supported operations can interoperate with libsodium across languages.

Doing cryptography properly is hard. While no human is infallible, computers are pretty good at following instructions. Humans are bad at following instructions, but they do a decent job of giving instructions, provided they can effectively communicate intent. Thus, if the instructions humans give the computer are correct, we can be reasonably assured that the operations the computer does are correct too.

This library tries to make it easy to give the computer the correct instructions, and it does so by providing well-known implementations of general-purpose cryptography functions, in an API that’s relatively easy to use, type safe, and hard to use incorrectly.

As the name of this library implies, one should avoid trying to “roll their own crypto”, as it often results in avoidable mistakes. In the context of cryptography, mistakes can be very costly.

This crate uses the Rust 2024 edition. The minimum supported Rust version (MSRV) is Rust 1.89 or newer.

Rust 2024 reserves gen as a keyword. Prefer generation APIs such as Key::generate(). Existing gen APIs remain available through raw identifier syntax, such as Key::r#gen(), for compatibility and are deprecated.

Features

• 100% pure Rust, no hidden C libraries
• mostly free of unsafe code²
• Hard to misuse, helping you avoid common costly cryptography mistakes
• Many libsodium features implemented with both Classic and Rustaceous API
• Protected memory handling (mprotect() + mlock(), along with Windows equivalents) on stable Rust for Unix and Windows targets, enabled by default with the protected feature
• Password-hash string helpers enabled by default with the base64 feature
• Serde support (with features = ["serde"])
• wincode support for direct binary serialization of Rustaceous box types (with features = ["wincode"])
• Portable SIMD implementations on nightly, with features = ["simd_backend", "nightly"]:
  • Blake2b (used by generic hashing, password hashing, and key derivation)
  • Argon2 block mixing (used by password hashing)
  • Salsa20 (used by XSalsa20-Poly1305 secretbox)
  • Poly1305 (used by one-time authentication and secret boxes), except on AArch64 where dryoc keeps the soft backend because the portable-SIMD path is slower there
• curve25519-dalek (used by public/private key functions) selects its own serial or x86_64 vector backend at build time
• SHA2 (used by sealed boxes) includes SIMD implementation for AVX2
• ChaCha20 (used by streaming interface) includes SIMD implementations for NEON, AVX2, and SSE2

The simd_backend and nightly features enable dryoc’s portable SIMD backends. CPU-specific dependency backends and local benchmarking may also benefit from target-specific RUSTFLAGS:

• For AVX2 set RUSTFLAGS=-Ctarget-cpu=haswell -Ctarget-feature=+avx2
• For SSE2 set RUSTFLAGS=-Ctarget-feature=+sse2
• For NEON set RUSTFLAGS=-Ctarget-feature=+neon
• For local Apple Silicon benchmarks, use RUSTFLAGS=-Ctarget-cpu=native. NEON is part of the AArch64 macOS baseline target, so adding -Ctarget-feature=+neon is not expected to change native results.

The Curve25519 backend is selected by curve25519-dalek, not by dryoc’s simd_backend feature.

Poly1305 is a special exception on AArch64: even with simd_backend and nightly enabled, dryoc uses the soft Poly1305 backend because profiling shows the portable-SIMD implementation is slower on that architecture.

Note that eventually this project will converge on portable SIMD implementations for all the core algos which will work across all platforms supported by LLVM, rather than relying on hand-coded assembly or intrinsics, but this is a work in progress.

See BENCHMARKS.md for side-by-side software and SIMD benchmark results.

APIs

This library includes both a Classic API, which is very similar to the original libsodium API, and Rustaceous API with Rust-specific features. Both APIs can be used together interchangeably, according to your preferences. The Rustaceous API is a wrapper around the underlying classic API.

It’s recommended that you use the Rustaceous API unless you have strong feelings about using the Classic API. The Classic API includes some pitfalls and traps that are also present in the original libsodium API, and unless you’re extra careful you could make mistakes. With the Rustaceous API, it’s harder to make mistakes thanks to strict type and safety features.

The Rustaceous API is, arguably, somewhat trickier to use, especially if you’re new to Rust. The Rustaceous API requires knowing and specifying the desired type in many cases. For your convenience, type aliases are provided for common types within each module. The Classic API only uses base types (fixed length byte arrays and byte slices).

Feature	Rustaceous API	Classic API	Reference
Public-key authenticated boxes	DryocBox	crypto_box	Link
Secret-key authenticated boxes	DryocSecretBox	crypto_secretbox	Link
Authenticated encryption with additional data	DryocAead	crypto_aead_xchacha20poly1305_ietf	Link
Streaming encryption	DryocStream	crypto_secretstream_xchacha20poly1305	Link
Generic hashing, HMAC	GenericHash	crypto_generichash	Link
SHA-3 hashing	Sha3256, Sha3512	crypto_hash	Link
Secret-key authentication	Auth	crypto_auth	Link
Direct HMAC authentication	Hmac	crypto_auth_hmacsha256, crypto_auth_hmacsha512, crypto_auth_hmacsha512256	Link
One-time authentication	OnetimeAuth	crypto_onetimeauth	Link
Key derivation	Kdf	crypto_kdf	Link
HKDF key derivation	Hkdf	crypto_kdf	Link
Key exchange	Session	crypto_kx	Link
Public-key signatures	SigningKeyPair	crypto_sign	Link
Password hashing	PwHash	crypto_pwhash	Link
Protected memory3	protected	N/A	Link
Short-input hashing	N/A	crypto_shorthash	Link

Using Serde

This crate includes optional Serde support which can be enabled with the serde feature flag. When enabled, the Serialize and Deserialize traits are provided for data structures.

Using wincode

This crate includes optional wincode support which can be enabled with the wincode feature flag. When enabled, wincode::SchemaWrite and wincode::SchemaRead are provided for supported Rustaceous box types, including DryocBox, DryocSecretBox, and AeadBox.

Unsafe code

Non-test unsafe code is limited to these areas:

Area	Feature gate	Why unsafe is required
src/types.rs fixed-size byte views	Always available	Converts validated byte slices and vectors into [u8; N] references without copying. Each cast is guarded by a length check or an exact-size wrapper invariant.
src/dryocbox.rs, src/dryocsecretbox.rs, and src/dryocaead.rs wincode impls	wincode	Implements unsafe wincode schema traits for the Rustaceous box wire formats. The implementations write and read initialized fields in the same order.
src/blake2b/blake2b_soft.rs and src/blake2b/blake2b_simd.rs parameter blocks	Always available for the soft backend; simd_backend,nightly for SIMD	Views a repr(C, packed) BLAKE2b parameter block as bytes so the initialization vector is mixed exactly as specified. The parameter type contains only initialized byte fields.
src/protected.rs protected memory	protected on Unix/Windows	Calls OS APIs such as mlock, mprotect, VirtualLock, and VirtualProtect, implements page-aligned guarded heap buffers, and exposes exact-size byte-array views over protected heap buffers.
src/classic/salsa20_simd.rs Salsa20 SIMD backend	simd_backend,nightly	Performs little-endian unaligned in-place and buffer-to-buffer word XOR in 256-byte chunks, plus volatile zeroization of cached SIMD lanes containing derived key material.

Test-only unsafe code is used for libsodium and Argon2 compatibility checks and protected-memory platform probes; it is not part of the runtime crate API.

Security notes

This crate has not been audited by any 3rd parties. It uses well-known implementations of the underlying algorithms which have been previously verified as using constant-time operations.

With that out of the way, the deterministic nature of cryptography and extensive testing used in this crate means it’s relatively safe to use, provided the underlying algorithms remain safe. Arguably, this crate is incredibly safe (as far as cryptography libraries go) thanks to the features provided by the API of this crate, and those provided by the Rust language itself.

Acknowledgements

Big ups to the authors and contributors of NaCl and libsodium for paving the way toward better cryptography libraries.

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1. Not actually trademarked. ↩

2. The protected memory features described in the protected mod are available on Unix and Windows targets with the default protected feature. Unsupported targets do not expose the protected-memory API. These features require custom memory allocation, system calls, and pointer arithmetic, which are unsafe in Rust. Some optional SIMD code, including dependency-provided SIMD implementations and small internal helpers, may contain unsafe code. In particular, many SIMD implementations are considered “unsafe” due to their use of assembly or intrinsics, however without SIMD-based cryptography you may be exposed to timing attacks. See the unsafe code section above for the non-test unsafe inventory in this crate. ↩

3. Available on Unix and Windows targets with the protected feature flag enabled. The protected feature is enabled by default. ↩

4. The Rustaceous API is designed to protect users of this library from making mistakes, however the Classic API allows one to do as one pleases. ↩

Modules

auth

Secret-key message authentication

classic

Classic API

constants

Constant value definitions

dryocaead

Authenticated encryption with additional data

dryocbox

Public-key authenticated encryption

dryocsecretbox

Secret-key authenticated encryption

dryocstream

Encrypted streams

generichash

Generic hashing

hkdf

HKDF key derivation

hmac

HMAC authentication

kdf

Key derivation functions

keypair

Public/secret keypair tools

kx

Key exchange functions

onetimeauth

One-time authentication

precalc

Precalculated secret key for use with precalc_* functions in crate::dryocbox::DryocBox

protectedprotected

Memory protection utilities

pwhash

Password hashing functions

rng

Random number generation utilities

sha3

SHA-3 hash algorithms

sha256

SHA-256 hash algorithm

sha512

SHA-512 hash algorithm

sign

Public-key signatures

types

Base type definitions

utils

Various utility functions

Enums

Error

Errors generated by Dryoc.