92 lines
3.2 KiB
Rust
92 lines
3.2 KiB
Rust
use std::collections::HashMap;
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use std::fs;
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use std::path::Path;
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use ed25519_dalek::{SigningKey, VerifyingKey};
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use serde::{Deserialize, Serialize};
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use uuid::Uuid;
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use x25519_dalek::EphemeralSecret;
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use backchannel_common::crypto::identity;
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use crate::error::{ClientError, Result};
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/// On-disk representation of the keystore.
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#[derive(Serialize, Deserialize)]
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struct KeystoreFile {
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/// Base64-encoded Ed25519 signing key (32 bytes).
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signing_key_b64: String,
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}
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/// Holds cryptographic material for the local client.
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pub struct Keystore {
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pub signing_key: SigningKey,
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pub verifying_key: VerifyingKey,
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/// Derived DM session keys cached in memory: peer_user_id → 32-byte key.
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/// Populated after completing an X25519 key exchange.
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pub dm_keys: HashMap<Uuid, [u8; 32]>,
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/// Ephemeral secrets awaiting the remote party's public key.
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/// Keyed by the peer's user UUID. Consumed on exchange completion.
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pub pending_ecdh: HashMap<Uuid, EphemeralSecret>,
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}
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impl Keystore {
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/// Load an existing keystore from `path`, or generate a fresh one and save it.
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pub fn load_or_create(path: &str) -> Result<Self> {
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if Path::new(path).exists() {
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let contents = fs::read_to_string(path)?;
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let file: KeystoreFile =
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serde_json::from_str(&contents).map_err(ClientError::Json)?;
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let signing_key = identity::b64_to_signing_key(&file.signing_key_b64)?;
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let verifying_key = signing_key.verifying_key();
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tracing::debug!("Loaded keystore from {}", path);
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Ok(Self::from_signing_key(signing_key, verifying_key))
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} else {
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let (signing_key, verifying_key) = identity::generate_keypair();
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let file = KeystoreFile {
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signing_key_b64: identity::signing_key_to_b64(&signing_key),
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};
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if let Some(parent) = Path::new(path).parent() {
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fs::create_dir_all(parent)?;
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}
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fs::write(path, serde_json::to_string_pretty(&file)?)?;
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tracing::info!("Generated new identity keypair, saved to {}", path);
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Ok(Self::from_signing_key(signing_key, verifying_key))
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}
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}
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fn from_signing_key(signing_key: SigningKey, verifying_key: VerifyingKey) -> Self {
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Self {
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signing_key,
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verifying_key,
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dm_keys: HashMap::new(),
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pending_ecdh: HashMap::new(),
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}
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}
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/// Base64-encoded Ed25519 public key, suitable for sending to the server.
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pub fn identity_pubkey_b64(&self) -> String {
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identity::pubkey_to_b64(&self.verifying_key)
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}
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/// Store an `EphemeralSecret` while waiting for the remote peer's response.
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pub fn store_pending_ecdh(&mut self, peer_id: Uuid, secret: EphemeralSecret) {
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self.pending_ecdh.insert(peer_id, secret);
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}
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/// Retrieve and remove a pending ephemeral secret (consumed by ECDH).
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pub fn take_pending_ecdh(&mut self, peer_id: Uuid) -> Option<EphemeralSecret> {
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self.pending_ecdh.remove(&peer_id)
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}
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pub fn cache_dm_key(&mut self, peer_id: Uuid, key: [u8; 32]) {
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self.dm_keys.insert(peer_id, key);
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}
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pub fn get_dm_key(&self, peer_id: &Uuid) -> Option<&[u8; 32]> {
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self.dm_keys.get(peer_id)
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}
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}
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