Remove AES functions in aes.ts and export new ones for backward compatibility

Author: florianduros

src/crypto/aes.ts

@@ -14,153 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { decodeBase64, encodeBase64 } from "../base64.ts";
-
-// salt for HKDF, with 8 bytes of zeros
-const zeroSalt = new Uint8Array(8);
-
-export interface IEncryptedPayload {
-    [key: string]: any; // extensible
-    /** the initialization vector in base64 */
-    iv: string;
-    /** the ciphertext in base64 */
-    ciphertext: string;
-    /** the HMAC in base64 */
-    mac: string;
-}
-
-/**
- * Encrypt a string using AES-CTR.
- *
- * @param data - the plaintext to encrypt
- * @param key - the encryption key to use as an input to the HKDF function which is used to derive the AES key for
- *    encryption. Obviously, the same key must be provided when decrypting.
- * @param name - the name of the secret. Used as an input to the HKDF operation which is used to derive the AES key,
- *    so again the same value must be provided when decrypting.
- * @param ivStr - the base64-encoded initialization vector to use. If not supplied, a random one will be generated.
- *
- * @returns The encrypted result, including the ciphertext itself, the initialization vector (as supplied in `ivStr`,
- *   or generated), and an HMAC on the ciphertext — all base64-encoded.
- */
-export async function encryptAES(
-    data: string,
-    key: Uint8Array,
-    name: string,
-    ivStr?: string,
-): Promise<IEncryptedPayload> {
-    let iv: Uint8Array;
-    if (ivStr) {
-        iv = decodeBase64(ivStr);
-    } else {
-        iv = new Uint8Array(16);
-        globalThis.crypto.getRandomValues(iv);
-
-        // clear bit 63 of the IV to stop us hitting the 64-bit counter boundary
-        // (which would mean we wouldn't be able to decrypt on Android). The loss
-        // of a single bit of iv is a price we have to pay.
-        iv[8] &= 0x7f;
-    }
-
-    const [aesKey, hmacKey] = await deriveKeys(key, name);
-    const encodedData = new TextEncoder().encode(data);
-
-    const ciphertext = await globalThis.crypto.subtle.encrypt(
-        {
-            name: "AES-CTR",
-            counter: iv,
-            length: 64,
-        },
-        aesKey,
-        encodedData,
-    );
-
-    const hmac = await globalThis.crypto.subtle.sign({ name: "HMAC" }, hmacKey, ciphertext);
-
-    return {
-        iv: encodeBase64(iv),
-        ciphertext: encodeBase64(ciphertext),
-        mac: encodeBase64(hmac),
-    };
-}
-
-/**
- * Decrypt an AES-encrypted string.
- *
- * @param data - the encrypted data, returned by {@link encryptAES}.
- * @param key - the encryption key to use as an input to the HKDF function which is used to derive the AES key. Must
- *    be the same as provided to {@link encryptAES}.
- * @param name - the name of the secret. Also used as an input to the HKDF operation which is used to derive the AES
- *    key, so again must be the same as provided to {@link encryptAES}.
- */
-export async function decryptAES(data: IEncryptedPayload, key: Uint8Array, name: string): Promise<string> {
-    const [aesKey, hmacKey] = await deriveKeys(key, name);
-
-    const ciphertext = decodeBase64(data.ciphertext);
-
-    if (!(await globalThis.crypto.subtle.verify({ name: "HMAC" }, hmacKey, decodeBase64(data.mac), ciphertext))) {
-        throw new Error(`Error decrypting secret ${name}: bad MAC`);
-    }
-
-    const plaintext = await globalThis.crypto.subtle.decrypt(
-        {
-            name: "AES-CTR",
-            counter: decodeBase64(data.iv),
-            length: 64,
-        },
-        aesKey,
-        ciphertext,
-    );
-
-    return new TextDecoder().decode(new Uint8Array(plaintext));
-}
-
-async function deriveKeys(key: Uint8Array, name: string): Promise<[CryptoKey, CryptoKey]> {
-    const hkdfkey = await globalThis.crypto.subtle.importKey("raw", key, { name: "HKDF" }, false, ["deriveBits"]);
-    const keybits = await globalThis.crypto.subtle.deriveBits(
-        {
-            name: "HKDF",
-            salt: zeroSalt,
-            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-            // @ts-ignore: https://github.com/microsoft/TypeScript-DOM-lib-generator/pull/879
-            info: new TextEncoder().encode(name),
-            hash: "SHA-256",
-        },
-        hkdfkey,
-        512,
-    );
-
-    const aesKey = keybits.slice(0, 32);
-    const hmacKey = keybits.slice(32);
-
-    const aesProm = globalThis.crypto.subtle.importKey("raw", aesKey, { name: "AES-CTR" }, false, [
-        "encrypt",
-        "decrypt",
-    ]);
-
-    const hmacProm = globalThis.crypto.subtle.importKey(
-        "raw",
-        hmacKey,
-        {
-            name: "HMAC",
-            hash: { name: "SHA-256" },
-        },
-        false,
-        ["sign", "verify"],
-    );
-
-    return Promise.all([aesProm, hmacProm]);
-}
-
-// string of zeroes, for calculating the key check
-const ZERO_STR = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
-
-/** Calculate the MAC for checking the key.
- *
- * @param key - the key to use
- * @param iv - The initialization vector as a base64-encoded string.
- *     If omitted, a random initialization vector will be created.
- * @returns An object that contains, `mac` and `iv` properties.
- */
-export function calculateKeyCheck(key: Uint8Array, iv?: string): Promise<IEncryptedPayload> {
-    return encryptAES(ZERO_STR, key, "", iv);
-}
+// Export for backwards compatibility
+export type { SecretEncryptedPayload as IEncryptedPayload } from "../utils/encryptAES.ts";
+export { encryptAES } from "../utils/encryptAES.ts";
+export { decryptAES } from "../utils/decryptAES.ts";