消息身份验证代码 (MAC)
使用集合让一切井井有条
根据您的偏好保存内容并对其进行分类。
借助 MAC 基元，您可以验证是否有人篡改了您的数据。与收件人共享对称密钥的发件人可以为给定消息计算身份验证标记，以便收件人验证消息是否来自预期的发件人且未经修改。
MAC 具有以下属性：
- 真实性：知道密钥是创建可验证 MAC 标记的唯一方法。
- Symmetric：计算和验证标记需要使用相同的密钥。
MAC 可以是确定性的，也可以是随机的，具体取决于算法。Tink 目前未实现非确定性 MAC 算法。您应仅将 MAC 用于消息身份验证，而不要用于生成伪随机字节等其他用途（如需了解，请参阅 PRF）。
如果您需要使用非对称基元，请参阅数字签名。
选择密钥类型
对于大多数用途，我们建议使用 HMAC_SHA256，但也有一些其他选项。
一般来说，以下情况成立：
最低安全保障
- 身份验证强度至少为 80 位
- 在选择明文攻击下防范实存伪造
- 至少 128 位安全性，可防范密钥恢复攻击，以及多用户场景（当攻击者不是针对特定密钥，而是针对最多 232 个密钥中的任意密钥时）
用例示例
请参阅我想保护数据免遭篡改。
如未另行说明，那么本页面中的内容已根据知识共享署名 4.0 许可获得了许可，并且代码示例已根据 Apache 2.0 许可获得了许可。有关详情，请参阅 Google 开发者网站政策。Java 是 Oracle 和/或其关联公司的注册商标。
最后更新时间 (UTC)：2025-07-25。
[null,null,["最后更新时间 (UTC)：2025-07-25。"],[[["\u003cp\u003eThe Message Authentication Code (MAC) primitive, using a shared symmetric key, enables verification of data integrity and authenticity by generating an authentication tag.\u003c/p\u003e\n"],["\u003cp\u003eMAC ensures authenticity as only the key holder can create a verifiable tag, and it's symmetric, requiring the same key for both computation and verification.\u003c/p\u003e\n"],["\u003cp\u003eTink recommends HMAC_SHA256 for most use cases, while HMAC_SHA512 offers higher security and AES256_CMAC might provide better performance with specific hardware.\u003c/p\u003e\n"],["\u003cp\u003eTink's MAC implementation guarantees a minimum of 80-bit authentication strength, protection against forgery, and at least 128-bit security against key recovery attacks, even in multi-user environments.\u003c/p\u003e\n"]]],["MAC uses a shared symmetric key between sender and recipient to verify message authenticity and integrity. The sender computes an authentication tag for a message, which the recipient uses to confirm its origin and unaltered state. MAC guarantees authenticity, where only key holders can create verifiable tags. Key recommendations include HMAC_SHA256, HMAC_SHA512 (most conservative), and AES256_CMAC (fastest with AES-NI). MAC is designed solely for message authentication, offering a minimum of 80-bit authentication strength.\n"],null,["# Message Authentication Code (MAC)\n\nThe MAC primitive lets you to verify that no one has tampered with your data.\nA sender sharing a *symmetric key* with a recipient can compute an\n*authentication tag* for a given message, which allows the recipient to verify\nthat a message is from the expected sender and has not been modified.\n\nMAC has the following properties:\n\n- **Authenticity**: Knowing the key is the only way to create a verifiable MAC tag.\n- **Symmetric**: Computing and verifying the tag requires the same key.\n\nMAC can be deterministic or randomized, depending on the algorithm. Tink does\nnot implement non-deterministic MAC algorithms at the moment. You should use MAC\nonly for message authentication, not for other purposes like generation of\npseudorandom bytes (for that, see [PRF](/tink/prf)).\n\nIf you need an asymmetric primitive instead, see [Digital\nSignature](/tink/digital-signature).\n\n### Choose a key type\n\nWe recommend using **HMAC_SHA256** for most uses, but there are other options as\nwell.\n\nIn general, the following holds true:\n\n- HMAC_SHA512 may or may not be faster depending on your message size and the specifics of the hardware you use.\n- HMAC_SHA512 is the most conservative mode that can be used for practically unlimited number of messages.\n- AES256_CMAC is fastest on systems that support the [AES-NI](https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-encryption-standard-instructions-aes-ni.html) hardware\n acceleration.\n\n | **Note:** Tink doesn't offer AES128_CMAC because it doesn't offer 128-bit security in multi-user scenarios.\n\n### Minimal security guarantees\n\n- At least 80-bit authentication strength\n- Secure against existential forgery under chosen plaintext attack\n- At least 128-bit security against key recovery attacks, and also in multi-user scenarios (when an attacker is not targeting a specific key, but any key from a set of up to 2^32^ keys)\n\n### Example use case\n\nSee [I want to protect data from tampering](/tink/protect-data-from-tampering)."]]
