afbaca1112
- Protocol spec: encrypted envelope format, device identity (Ed25519 + X25519), LWW conflict resolution with Lamport clocks - E2E encryption: XChaCha20-Poly1305 via sodium-native, X25519 key exchange - WebSocket relay server: stateless message forwarding, device auth via challenge-response, offline message queuing, ping/pong keepalive - Device pairing: time-limited pairing codes, key exchange broker via HTTP - Sync protocol: envelope builder/opener, conflict-resolving cookie store - 31 tests passing (crypto, pairing, conflict resolution, full integration) Co-Authored-By: Paperclip <noreply@paperclip.ing>
69 lines
1.8 KiB
TypeScript
69 lines
1.8 KiB
TypeScript
import sodium from "sodium-native";
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/**
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* Derive a shared secret from our X25519 secret key and peer's X25519 public key.
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* Uses crypto_scalarmult (raw X25519 ECDH) then hashes with crypto_generichash
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* to produce a 32-byte symmetric key.
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*/
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export function deriveSharedKey(
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ourEncSec: Buffer,
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peerEncPub: Buffer,
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): Buffer {
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const raw = Buffer.alloc(sodium.crypto_scalarmult_BYTES);
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sodium.crypto_scalarmult(raw, ourEncSec, peerEncPub);
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// Hash the raw shared secret to get a uniform key
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const sharedKey = Buffer.alloc(32);
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sodium.crypto_generichash(sharedKey, raw);
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return sharedKey;
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}
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/**
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* Encrypt plaintext using XChaCha20-Poly1305 with the shared key.
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* Returns { nonce, ciphertext } where both are Buffers.
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*/
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export function encrypt(
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plaintext: Buffer,
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sharedKey: Buffer,
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): { nonce: Buffer; ciphertext: Buffer } {
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const nonce = Buffer.alloc(sodium.crypto_aead_xchacha20poly1305_ietf_NPUBBYTES);
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sodium.randombytes_buf(nonce);
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const ciphertext = Buffer.alloc(
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plaintext.length + sodium.crypto_aead_xchacha20poly1305_ietf_ABYTES,
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);
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sodium.crypto_aead_xchacha20poly1305_ietf_encrypt(
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ciphertext,
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plaintext,
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null, // no additional data
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null, // unused nsec
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nonce,
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sharedKey,
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);
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return { nonce, ciphertext };
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}
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/**
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* Decrypt ciphertext using XChaCha20-Poly1305 with the shared key.
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* Returns the plaintext Buffer, or throws on authentication failure.
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*/
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export function decrypt(
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ciphertext: Buffer,
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nonce: Buffer,
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sharedKey: Buffer,
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): Buffer {
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const plaintext = Buffer.alloc(
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ciphertext.length - sodium.crypto_aead_xchacha20poly1305_ietf_ABYTES,
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);
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sodium.crypto_aead_xchacha20poly1305_ietf_decrypt(
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plaintext,
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null, // unused nsec
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ciphertext,
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null, // no additional data
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nonce,
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sharedKey,
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);
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return plaintext;
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}
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