91 lines
2.8 KiB
TypeScript
91 lines
2.8 KiB
TypeScript
/**
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* File encryption for claudemesh E2E file sharing.
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*
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* Symmetric: crypto_secretbox_easy with random Kf (32-byte key).
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* Key wrapping: crypto_box_seal to recipient's X25519 pub (converted from ed25519).
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* Key opening: crypto_box_seal_open with own X25519 keypair.
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*/
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import { ensureSodium } from "./keypair";
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export interface EncryptedFile {
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ciphertext: Uint8Array; // secretbox ciphertext (includes MAC)
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nonce: string; // base64 24-byte nonce
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key: Uint8Array; // 32-byte symmetric Kf (keep in memory only)
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}
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/**
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* Encrypt file bytes with a fresh random symmetric key.
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* Returns ciphertext, nonce (base64), and the plaintext Kf.
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*/
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export async function encryptFile(plaintext: Uint8Array): Promise<EncryptedFile> {
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const sodium = await ensureSodium();
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const key = sodium.randombytes_buf(sodium.crypto_secretbox_KEYBYTES);
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const nonce = sodium.randombytes_buf(sodium.crypto_secretbox_NONCEBYTES);
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const ciphertext = sodium.crypto_secretbox_easy(plaintext, nonce, key);
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return {
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ciphertext,
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nonce: sodium.to_base64(nonce, sodium.base64_variants.ORIGINAL),
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key,
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};
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}
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/**
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* Decrypt file bytes with the symmetric key Kf.
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* Returns null if decryption fails.
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*/
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export async function decryptFile(
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ciphertext: Uint8Array,
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nonceB64: string,
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key: Uint8Array,
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): Promise<Uint8Array | null> {
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const sodium = await ensureSodium();
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try {
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const nonce = sodium.from_base64(nonceB64, sodium.base64_variants.ORIGINAL);
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return sodium.crypto_secretbox_open_easy(ciphertext, nonce, key);
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} catch {
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return null;
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}
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}
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/**
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* Seal Kf for a recipient using crypto_box_seal (ephemeral sender key).
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* recipientPubkeyHex: ed25519 pubkey of recipient (64 hex chars).
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* Returns base64 sealed box.
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*/
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export async function sealKeyForPeer(
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kf: Uint8Array,
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recipientPubkeyHex: string,
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): Promise<string> {
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const sodium = await ensureSodium();
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const recipientCurve = sodium.crypto_sign_ed25519_pk_to_curve25519(
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sodium.from_hex(recipientPubkeyHex),
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);
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const sealed = sodium.crypto_box_seal(kf, recipientCurve);
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return sodium.to_base64(sealed, sodium.base64_variants.ORIGINAL);
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}
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/**
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* Open a sealed key blob using own ed25519 keypair (converted to X25519).
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* Returns the 32-byte Kf or null if decryption fails.
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*/
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export async function openSealedKey(
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sealedB64: string,
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myPubkeyHex: string,
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mySecretKeyHex: string,
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): Promise<Uint8Array | null> {
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const sodium = await ensureSodium();
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try {
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const myCurvePub = sodium.crypto_sign_ed25519_pk_to_curve25519(
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sodium.from_hex(myPubkeyHex),
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);
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const myCurveSec = sodium.crypto_sign_ed25519_sk_to_curve25519(
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sodium.from_hex(mySecretKeyHex),
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);
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const sealed = sodium.from_base64(sealedB64, sodium.base64_variants.ORIGINAL);
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return sodium.crypto_box_seal_open(sealed, myCurvePub, myCurveSec);
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} catch {
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return null;
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}
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}
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