Hmac Generator
What is a Hmac Generator?
Compute Hash-based Message Authentication Codes (HMAC) using secret keys and cryptographic hash algorithms (HMAC-SHA256, HMAC-SHA512, HMAC-MD5, HMAC-SHA1) per RFC 2104 specifications.
Why Use This Tool?
- API Request Signing: Verify HMAC signatures for webhook notifications (Stripe, GitHub, Shopify webhooks).
- REST API Authentication: Generate HMAC header signatures for secure API request integrity.
- Tamper-Proof Data Verification: Ensure text messages have not been tampered with in transit.
How to Use
- Enter Secret Key string.
- Enter Message Text payload.
- Select Hash Algorithm (HMAC-SHA256 recommended) to view output hex or base64 signature.
Real Working Example
Input:
Secret Key: "my_api_secret_key" | Message: "GET /api/v1/orders" | Algorithm: HMAC-SHA256
Output Result:
HMAC-SHA256 Hex Digest: 5b2d8e4f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d
Important Technical Details & Security Standards
- RFC 2104 HMAC Algorithm: `HMAC(K, m) = H((K' ^ opad) || H((K' ^ ipad) || m))` using inner (ipad 0x36) and outer (opad 0x5C) key padding.
- Hex & Base64 Signature Formatting: Output signature formatted as Hexadecimal or Base64 string.
- Local Memory Execution: Zero network overhead.
Related Security & Crypto Tools
- Hash Text: Compute SHA256 and MD5 hashes.
- JWT Generator: Sign JSON Web Tokens with HMAC.
- SRI Hash Generator: Generate Subresource Integrity hashes.
Frequently Asked Questions
What is HMAC?
HMAC (Hash-based Message Authentication Code) is a specific construction for calculating message authentication codes involving a cryptographic hash function and a secret cryptographic key.
Why is HMAC safer than plain hashing for API webhooks?
HMAC requires a shared secret key, preventing attackers from modifying request data and recomputing plain hashes.
Which HMAC algorithm is standard for webhooks like Stripe or GitHub?
HMAC-SHA256 is the modern industry standard for webhook signature verification.
Is it free?
Yes, 100% free.
Are my secret key and message sent to a server?
No, all HMAC generation runs 100% locally inside your web browser.
Can I format HMAC output as Base64?
Yes, toggle between Hexadecimal and Base64 output formatting.