dcrypt-pke

dcrypt-pke provides dcrypt-specific ECIES constructions for P-224, P-256, P-384, and P-521. Each construction generates a fresh ephemeral EC key, derives an AEAD key from a transcript-bound ECDH value with HKDF, and authenticates the payload and caller-provided associated data.

P-224 remains available for interoperability at approximately 112-bit security; prefer P-256 or stronger for new designs. P-192 was removed for v3.

Key generation and encryption require a caller-owned cryptographic RNG. dcrypt does not select or access an operating-system RNG.

use dcrypt::api::traits::Pke;
use dcrypt::internal::{CryptoRng, RngCore};
use dcrypt::pke::EciesP256;

fn roundtrip<R: CryptoRng + RngCore>(rng: &mut R) -> dcrypt::api::Result<()> {
    let (public_key, secret_key) = EciesP256::keypair(rng)?;
    let aad = Some(b"protocol context".as_slice());
    let ciphertext = EciesP256::encrypt(&public_key, b"secret", aad, rng)?;
    let plaintext = EciesP256::decrypt(&secret_key, &ciphertext, aad)?;
    assert_eq!(plaintext, b"secret");
    Ok(())
}

This is not HPKE and it does not provide forward secrecy against later compromise of the recipient's long-term private key. Treat the exact v3 framing, KDF transcript, and suite labels as protocol identifiers rather than a generic ECIES interoperability claim.

The default std feature implies alloc. Allocation-backed no_std builds use default-features = false, features = ["alloc"].