hmac hash-256 算法 HS256
exportKey(key: CryptoKey): Promise<ArrayBuffer>
private
initCryptoKey(force?: boolean): Promise<void>
sign(data: ArrayBuffer): Promise<ArrayBuffer>
verify(signature: ArrayBuffer,data: ArrayBuffer,): Promise<boolean>
parseKey(serverKey: ArrayBuffer): Promise<CryptoKey>
sign(key: CryptoKey,data: ArrayBuffer,): Promise<ArrayBuffer>