ling_crypto/
asymmetric.rs

1//! Ed25519 digital signatures and X25519 Diffie-Hellman key exchange.
2
3use ed25519_dalek::{Signature, Signer, SigningKey, Verifier, VerifyingKey};
4use rand::rngs::OsRng;
5use x25519_dalek::{PublicKey, StaticSecret};
6use zeroize::Zeroizing;
7
8// ── Ed25519 ───────────────────────────────────────────────────────────────────
9
10pub struct Ed25519Keypair {
11    signing_key: SigningKey,
12}
13
14impl Ed25519Keypair {
15    pub fn generate() -> Self {
16        Self { signing_key: SigningKey::generate(&mut OsRng) }
17    }
18
19    pub fn from_seed(seed: [u8; 32]) -> Self {
20        Self { signing_key: SigningKey::from_bytes(&seed) }
21    }
22
23    pub fn public_key(&self) -> [u8; 32] {
24        self.signing_key.verifying_key().to_bytes()
25    }
26
27    pub fn sign(&self, msg: &[u8]) -> [u8; 64] {
28        self.signing_key.sign(msg).to_bytes()
29    }
30
31    pub fn verify(pubkey: &[u8; 32], msg: &[u8], sig: &[u8; 64]) -> Result<(), &'static str> {
32        let vk = VerifyingKey::from_bytes(pubkey).map_err(|_| "invalid pubkey")?;
33        let signature = Signature::from_bytes(sig);
34        vk.verify(msg, &signature).map_err(|_| "signature invalid")
35    }
36
37    pub fn to_bytes(&self) -> Zeroizing<[u8; 32]> {
38        Zeroizing::new(self.signing_key.to_bytes())
39    }
40}
41
42// ── X25519 ECDH ───────────────────────────────────────────────────────────────
43
44pub struct X25519Secret {
45    secret: StaticSecret,
46}
47
48impl X25519Secret {
49    pub fn generate() -> Self {
50        Self { secret: StaticSecret::random_from_rng(OsRng) }
51    }
52
53    pub fn from_bytes(bytes: [u8; 32]) -> Self {
54        Self { secret: StaticSecret::from(bytes) }
55    }
56
57    pub fn public_key(&self) -> [u8; 32] {
58        PublicKey::from(&self.secret).to_bytes()
59    }
60
61    /// Perform ECDH and return 32-byte shared secret.
62    pub fn diffie_hellman(&self, their_pubkey: &[u8; 32]) -> [u8; 32] {
63        let their_pk = PublicKey::from(*their_pubkey);
64        self.secret.diffie_hellman(&their_pk).to_bytes()
65    }
66}
ling_crypto/asymmetric.rs

ling_crypto/
asymmetric.rs
