alt-tls

This crate provides TLS configurations usable by rustls that support the modern ed25519 signature scheme and x25519 key exchange, and also blake3 for hashing and HMAC substitution.

Identity Management

Two binaries are provided: generate_ed25519_identity and import_ed25519_identity which generate (or import from hex) ed25519 secret signing key identities, and outputs the key in hex, in PEM, and also as a self-signed certificate in PEM.

The certificate generated has af Distinguised Name with an alternate name that simply reads "IGNORE THE NAME, DETERMINE TRUST FROM THE KEY".

TLS

We provide a TLS provider by calling provider() which internally provides and supports a very limited TLS configuration:

• TLS 1.3 only
• Signature algorithm is ed25519 only
• AEAD is chacha20-poly1305 only
• Hash is SHA256 or Blake3 only
• HMAC is SHA256 or Blake3 (directly using blake3 keyed hash, not HMAC construction)

You can run the example/server.rs and example/client.rs and they will talk to each other over TLS using our provider.

Cryptography Providers

We currently are using these:

sha256: RustCrypto/hashes

blake3: BLAKE3-team/BLAKE3

chacha20poly1305: RustCrypto/AEADs

ed25519 and x25519: curve25519-dalek

hmac: RustCrypto/MACs

Debugging / Inspecting

For deeper inspection into the TLS you can set some environment varibles when you run the examples, e.g.

$ RUST_LOG=rustls=trace SSLKEYLOGFILE=sslkeys-server.log cargo run --example server
$ RUST_LOG=rustls=trace SSLKEYLOGFILE=sslkeys-client.log cargo run --example client

HPKE

HPKE RFC 9180 standardizes public key encryption. We expose a copy of the rustls implementation of an HPKE provider. DHKEM_X25519_HKDF_SHA256_CHACHA20_POLY1305 looks nice.

What is an HPKE? It is a newly standardized way to send an encrypted message to someone when you just know their public key, adopted into TLS and elsewhere. Previously we had a lot of incompatible implementations like BouncyCastle, NaCl box, etc.

TODO

• Support for secp256k1
• Figure out why rustls providers for TLS 1.3 don't specify (nor can use) ECDHE or PSK