Function cbcEncrypt

src/lib/content_encryption.ts:115–139

(
  enc: string,
  plaintext: Uint8Array,
  cek: Uint8Array | types.CryptoKey,
  iv: Uint8Array,
  aad: Uint8Array,
)

// --- CBC encrypt/decrypt ---

async function cbcEncrypt(
  enc: string,
  plaintext: Uint8Array,
  cek: Uint8Array | types.CryptoKey,
  iv: Uint8Array,
  aad: Uint8Array,
) {
  const { encKey, macKey, keySize } = await cbcKeySetup(enc, cek, 'encrypt')

  const ciphertext = new Uint8Array(
    await crypto.subtle.encrypt(
      {
        iv: iv as Uint8Array<ArrayBuffer>,
        name: 'AES-CBC',
      },
      encKey,
      plaintext as Uint8Array<ArrayBuffer>,
    ),
  )

  const macData = concat(aad, iv, ciphertext, uint64be(aad.length << 3))
  const tag = await cbcHmacTag(macKey, macData, keySize)

  return { ciphertext, tag, iv }
}

async function timingSafeEqual(a: Uint8Array, b: Uint8Array): Promise<boolean> {
  if (!(a instanceof Uint8Array)) {