KrabiTLS
A hobby no_std TLS 1.3 client for microcontrollers. Don't use it for anything you care about.
- TLS 1.3; X25519 or X25519MLKEM768 key exchange
- Verifies Ed25519, RSA, or ML-DSA server certificates
- Bundled trust is pin-a-pubkey or trust-SAN — no CA bundle or chain walking; verification is a pluggable
VerifyStrategy - Hand-rolled, unaudited, not constant-time, no scalar blinding
No heap allocations, and prefer reduced flash + stack size over speed.
Resource usage
Cortex-M3 and RV32IMAC footprint — real-minus-baseline .text and peak stack.
| Target | Suite | KEX / Sig | .text (KiB) | Stack (B) |
|---|---|---|---|---|
| M3 | ChaCha20-Poly1305 | X25519 / Ed25519 | 37.3 | 10916 |
| M3 | AES-128-GCM | X25519 / Ed25519 | 41.8 | 16444 |
| M3 | AES-128-GCM | X25519 / RSA-2048-PSS | 55.5 | 31292 |
| M3 | AES-128-GCM | X25519MLKEM768 / ML-DSA-44 | 60.6 | 117252 |
| RV32IMAC | ChaCha20-Poly1305 | X25519 / Ed25519 | 55.9 | 10692 |
| RV32IMAC | AES-128-GCM | X25519 / Ed25519 | 65.2 | 16212 |
| RV32IMAC | AES-128-GCM | X25519 / RSA-2048-PSS | 88.2 | 31012 |
| RV32IMAC | AES-128-GCM | X25519MLKEM768 / ML-DSA-44 | 93.0 | 117112 |
License
Apache 2.0; see LICENSE for details.