Hash Generator

What Is HMAC-SHA256?

HMAC (Hash-based Message Authentication Code) is not an ordinary hash algorithm — it is a mechanism for verifying both data integrity and sender authenticity. HMAC-SHA256 combines a secret key with the SHA-256 algorithm to produce a 256-bit digital signature (64 characters).

How Does HMAC Work?

HMAC applies the SHA-256 algorithm twice: once with the secret key and message, and again on the result. This ensures that anyone without the secret key cannot generate or verify a valid HMAC.

Primary Use Cases

• API request authentication (AWS Signature, GitHub Webhooks)
• JWT (JSON Web Token) signing
• OAuth message and application verification
• Electronic payment request protection
• DKIM email message authentication

HMAC vs Plain SHA-256

SHA-256 ensures data integrity only — anyone can compute the same hash. HMAC-SHA256 ensures both integrity and authentication — only someone with the secret key can produce a valid signature.