HMAC 工具
SHA-512 HMAC generator
Try it
HMAC-SHA512 hex.
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How to use this tool, examples, and related tips.
Enter your message in the message field.
Enter your secret key.
The HMAC-SHA512 tag is computed instantly and displayed as a 128-character hexadecimal string.
Copy the output for use in your security pipeline, JWT workflow, or verification system.
HMAC-SHA512 is the HMAC construction applied using SHA-512 as the underlying hash function. It produces a 512-bit (128-character hex) authentication tag — the largest output in the SHA-2 HMAC family. SHA-512 operates on 64-bit words and processes 1024-bit blocks, making HMAC-SHA512 particularly efficient on 64-bit hardware for large messages. It is used in JWT tokens signed with HS512, high-security API authentication schemes, key derivation functions, and cryptographic protocols that require maximum MAC output length. Like all SHA-2 variants, SHA-512 has no known practical vulnerabilities.
JWT HS512 debugging — JWT tokens signed with HS512 use HMAC-SHA512. Reproduce the signature manually to debug token signing or verification failures.
High-security API authentication — Use HMAC-SHA512 when maximum authentication tag length is required by a security policy or protocol specification.
Key derivation inputs — HMAC-SHA512 is a component in several key derivation functions (e.g., HKDF with SHA-512) used in cryptographic protocol implementations.
Comparing HMAC output sizes — Use alongside HMAC-SHA256 to compare authentication tag lengths and understand the security-size trade-off across SHA-2 HMAC variants.
Answers about this tool and how your data is handled.
Both are considered secure with no known practical attacks. HMAC-SHA512 provides a larger authentication tag (512 vs 256 bits), offering greater theoretical collision resistance. For most applications, HMAC-SHA256 is sufficient.
On 64-bit hardware and for large inputs, yes — SHA-512 can outperform SHA-256 due to 64-bit word operations. For short messages, the difference is negligible.
No. HMAC computation runs entirely in your browser. Your message and secret key never leave your machine.
Always 128 hexadecimal characters, representing 512 bits.
HS512 — a symmetric JWT signing algorithm that uses HMAC-SHA512. Use the JWT decoder to inspect the algorithm field in a token's header before selecting the correct HMAC tool for debugging.
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HMAC 工具
HMAC-SHA512 hex.