关于 HMAC

HMAC (Hash-based Message Authentication Code) is a mechanism for calculating a message authentication code (MAC) involving a cryptographic hash function in combination with a secret cryptographic key. It can be used to verify the integrity and authenticity of a message.

HMAC 可以抵抗长度扩展攻击，并提供一种方法来确保消息未被篡改，并且发件人是他们声称的身份。HMAC 的安全性取决于底层哈希函数的加密强度和密钥的保密性。