| Property | Value |
|---|---|
| Algorithm | HMAC-SHA256 |
| Signed content | The exact request body bytes you transmit |
| Key | Your sign key |
| Output | Lowercase hexadecimal, 64 characters |
| Comparison | Byte-exact (hash_equals) — an uppercase signature is rejected |
| Encoding | UTF-8 |
| Request header | Signature: <hex> |
| Content-Type | application/json (a ;charset=utf-8 suffix is fine) — not part of the signature |