crypto.createDecipheriv(algorithm, key, iv[, options])

• algorithm <string>

• key <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView> | <KeyObject> | <CryptoKey>

• iv <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView> | <null>

• options <Object> stream.transform 选项

  ¥options <Object> stream.transform options

• 返回：<Decipher>

  ¥Returns: <Decipher>

创建并返回使用给定的 algorithm、key 和初始化向量（iv）的 Decipher 对象。

¥Creates and returns a Decipher object that uses the given algorithm, key and initialization vector (iv).

options 参数控制流行为并且是可选的，除非使用 CCM 或 OCB 模式（例如 'aes-128-ccm'）的密码。在这种情况下，需要 authTagLength 选项并以字节为单位指定身份验证标记的长度，请参阅 CCM 模式。对于 AES-GCM 和 chacha20-poly1305，authTagLength 选项默认为 16 字节，如果使用不同的长度，则必须将其设置为不同的值。

¥The options argument controls stream behavior and is optional except when a cipher in CCM or OCB mode (e.g. 'aes-128-ccm') is used. In that case, the authTagLength option is required and specifies the length of the authentication tag in bytes, see CCM mode. For AES-GCM and chacha20-poly1305, the authTagLength option defaults to 16 bytes and must be set to a different value if a different length is used.

algorithm 依赖于 OpenSSL，例如 'aes192' 等。在最近的 OpenSSL 版本中，openssl list -cipher-algorithms 将显示可用的密码算法。

¥The algorithm is dependent on OpenSSL, examples are 'aes192', etc. On recent OpenSSL releases, openssl list -cipher-algorithms will display the available cipher algorithms.

key 是 algorithm 使用的原始密钥，iv 是 初始化向量。两个参数都必须是 'utf8' 编码的字符串、缓冲区、TypedArray 或 DataView。key 可以是 secret 类型的 KeyObject。如果加密不需要初始化向量，则 iv 可以是 null。

¥The key is the raw key used by the algorithm and iv is an initialization vector. Both arguments must be 'utf8' encoded strings, Buffers, TypedArray, or DataViews. The key may optionally be a KeyObject of type secret. If the cipher does not need an initialization vector, iv may be null.

为 key 或 iv 传递字符串时，请考虑 使用字符串作为加密 API 的输入时的注意事项。

¥When passing strings for key or iv, please consider caveats when using strings as inputs to cryptographic APIs.

初始化向量应该是不可预测的和唯一的；理想情况下，它们将是加密随机的。他们不必是秘密的：IV 通常只是添加到未加密的密文消息中。有些东西必须是不可预测的和独特的，但不一定是秘密的，这听起来可能很矛盾；请记住，攻击者不能提前预测给定的 IV 是什么。

¥Initialization vectors should be unpredictable and unique; ideally, they will be cryptographically random. They do not have to be secret: IVs are typically just added to ciphertext messages unencrypted. It may sound contradictory that something has to be unpredictable and unique, but does not have to be secret; remember that an attacker must not be able to predict ahead of time what a given IV will be.