cortex25519

Implementations of X25519 key agreement and Ed25519 signatures, optimized with ASM for Cortex-M4 processors or higher (ARMv7E-M or higher).

Not reviewed, could have bugs, use at your own risk, etc etc.

Usage

The crate can be used directly through the x25519 and ed25519 modules, or as the driver behind embassy-crypto.

Each driver is behind one Cargo feature named embassy-crypto-<operation> (embassy-crypto-x25519, embassy-crypto-ed25519). Enabling it registers this crate's implementation as the global driver for that operation. The all feature enables both.

[dependencies]
embassy-crypto = "0.1"
cortex25519 = { version = "0.1", features = ["embassy-crypto-x25519", "embassy-crypto-ed25519"] }

To make sure Rust links this crate, add a dummy use like this:

use cortex25519 as _;

Ed25519 hashes with the embassy-crypto SHA-512 driver, so the application must register one (for example embassy-crypto-rustcrypto with the embassy-crypto-sha512 feature, or a HAL with a hardware SHA-512 driver).

Testing

qemu-tests runs the X25519 and Ed25519 suites of embassy-crypto-test (Wycheproof plus generated vectors) in QEMU; see its README.

Credits

Original X25519 ASM implementation by Emil Lenngren.

Extended to support Ed25519 verify by Dario Nieuwenhuis.

License

• Main cortex25519 crate is available under the BSD 2-clause license.
• Wycheproof test vectors are available under Apache license.