서버, 클라이언트, 서비스 워커 공용 코드를 lib/shared로 분리하고 브라우저 전용 모듈을 lib/client로 재구성

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/shared/crypto/aes.ts

@@ -0,0 +1,134 @@
+import { AES_GCM_IV_SIZE } from "#lib/shared/format/index.js";
+import {
+  encodeString,
+  decodeString,
+  encodeToBase64,
+  decodeFromBase64,
+  concatenateBuffers,
+} from "./encoding";
+
+export const generateMasterKey = async () => {
+  return {
+    masterKey: await crypto.subtle.generateKey(
+      {
+        name: "AES-KW",
+        length: 256,
+      } satisfies AesKeyGenParams,
+      true,
+      ["wrapKey", "unwrapKey"],
+    ),
+  };
+};
+
+export const generateDataKey = async () => {
+  return {
+    dataKey: await crypto.subtle.generateKey(
+      {
+        name: "AES-GCM",
+        length: 256,
+      } satisfies AesKeyGenParams,
+      true,
+      ["encrypt", "decrypt"],
+    ),
+    dataKeyVersion: new Date(),
+  };
+};
+
+export const makeAESKeyNonextractable = async (key: CryptoKey) => {
+  return await crypto.subtle.importKey(
+    "raw",
+    await crypto.subtle.exportKey("raw", key),
+    key.algorithm,
+    false,
+    key.usages,
+  );
+};
+
+export const wrapDataKey = async (dataKey: CryptoKey, masterKey: CryptoKey) => {
+  return encodeToBase64(await crypto.subtle.wrapKey("raw", dataKey, masterKey, "AES-KW"));
+};
+
+export const unwrapDataKey = async (dataKeyWrapped: string, masterKey: CryptoKey) => {
+  return {
+    dataKey: await crypto.subtle.unwrapKey(
+      "raw",
+      decodeFromBase64(dataKeyWrapped),
+      masterKey,
+      "AES-KW",
+      "AES-GCM",
+      false, // Nonextractable
+      ["encrypt", "decrypt"],
+    ),
+  };
+};
+
+export const wrapHmacSecret = async (hmacSecret: CryptoKey, masterKey: CryptoKey) => {
+  return encodeToBase64(await crypto.subtle.wrapKey("raw", hmacSecret, masterKey, "AES-KW"));
+};
+
+export const unwrapHmacSecret = async (hmacSecretWrapped: string, masterKey: CryptoKey) => {
+  return {
+    hmacSecret: await crypto.subtle.unwrapKey(
+      "raw",
+      decodeFromBase64(hmacSecretWrapped),
+      masterKey,
+      "AES-KW",
+      {
+        name: "HMAC",
+        hash: "SHA-256",
+      } satisfies HmacImportParams,
+      true, // Extractable
+      ["sign", "verify"],
+    ),
+  };
+};
+
+export const encryptData = async (data: BufferSource, dataKey: CryptoKey) => {
+  const iv = crypto.getRandomValues(new Uint8Array(12));
+  const ciphertext = await crypto.subtle.encrypt(
+    {
+      name: "AES-GCM",
+      iv,
+    } satisfies AesGcmParams,
+    dataKey,
+    data,
+  );
+  return { ciphertext, iv: iv.buffer };
+};
+
+export const decryptData = async (
+  ciphertext: BufferSource,
+  iv: string | BufferSource,
+  dataKey: CryptoKey,
+) => {
+  return await crypto.subtle.decrypt(
+    {
+      name: "AES-GCM",
+      iv: typeof iv === "string" ? decodeFromBase64(iv) : iv,
+    } satisfies AesGcmParams,
+    dataKey,
+    ciphertext,
+  );
+};
+
+export const encryptString = async (plaintext: string, dataKey: CryptoKey) => {
+  const { ciphertext, iv } = await encryptData(encodeString(plaintext), dataKey);
+  return { ciphertext: encodeToBase64(ciphertext), iv: encodeToBase64(iv) };
+};
+
+export const decryptString = async (ciphertext: string, iv: string, dataKey: CryptoKey) => {
+  return decodeString(await decryptData(decodeFromBase64(ciphertext), iv, dataKey));
+};
+
+export const encryptChunk = async (chunk: ArrayBuffer, dataKey: CryptoKey) => {
+  const { ciphertext, iv } = await encryptData(chunk, dataKey);
+  return concatenateBuffers(iv, ciphertext).buffer;
+};
+
+export const decryptChunk = async (encryptedChunk: ArrayBuffer, dataKey: CryptoKey) => {
+  return await decryptData(
+    encryptedChunk.slice(AES_GCM_IV_SIZE),
+    encryptedChunk.slice(0, AES_GCM_IV_SIZE),
+    dataKey,
+  );
+};