HMAC 生成器
使用 SHA-256、SHA-384 或 SHA-512 生成 HMAC 签名
什么是 HMAC？
HMAC（基于哈希的消息认证码）使用密钥结合哈希函数来验证数据的完整性和真实性。
使用方法
输入数值
在输入栏中填入您的数字或参数。
即时获取结果
结果在您输入时自动更新——无需按计算按钮。
复制或保存
将结果复制到剪贴板或用于您的工作流程。
为什么使用此工具
100% 免费
没有隐藏费用，没有付费等级——所有功能完全免费。
无需安装
完全在浏览器中运行。无需下载或安装任何软件。
隐私且安全
您的数据永远不会离开您的设备。不会上传至任何服务器。
支持移动设备
完全响应式设计——在手机、平板或桌面电脑上均可使用。
HMAC: Hash-Based Message Authentication Codes
Key Takeaways
- HMAC combines a cryptographic hash function with a secret key to provide both data integrity and authentication.
- Unlike plain hashes, HMAC proves that the message was created by someone who knows the secret key — preventing tampering and forgery.
- All HMAC generation is performed in your browser using the Web Crypto API — your keys and data remain private.
HMAC (Hash-based Message Authentication Code) is a mechanism for verifying both the integrity and authenticity of a message. It is used extensively in API authentication (AWS Signature V4), webhook verification (GitHub, Stripe), and secure communication protocols. HMAC is more secure than simple hash verification because it requires knowledge of a shared secret key.
HMAC-SHA256 is used to authenticate over 1 billion API requests per day across major cloud platforms.
Scale of Use
Key Concepts
How HMAC Works
HMAC processes the key through two rounds of hashing with different padding (ipad and opad), making it resistant to length extension attacks that affect plain hash functions.
HMAC vs. Plain Hash
A plain hash (SHA-256 of a message) can be computed by anyone. HMAC requires the secret key, so only authorized parties can generate a valid MAC. This provides authentication in addition to integrity.
Webhook Signature Verification
Services like GitHub and Stripe sign webhook payloads with HMAC-SHA256 using a shared secret. The receiver recomputes the HMAC and compares it with the signature header to verify authenticity.
Timing-Safe Comparison
When verifying HMAC signatures, always use constant-time comparison functions to prevent timing attacks that could leak information about the expected value byte by byte.
Pro Tips
Use HMAC-SHA256 as your default — it offers an excellent balance of security and performance for most applications.
Keep HMAC keys at least as long as the hash output (32 bytes for SHA-256) for maximum security.
Rotate HMAC keys periodically and support multiple active keys during transition periods.
Never log or expose HMAC keys in error messages, URLs, or client-side code.
All HMAC computation is performed entirely in your browser using the Web Crypto API. Your secret keys and message data are never transmitted to any external server.