# description
A digitally signed authentication credential in the HTTP `Authorization` header. Follows draft-cavage-http-signatures-12 as profiled by BECKN-006.  format: ``` Signature keyId="{subscriberId}|{uniqueKeyId}|{algorithm}",  algorithm="{algorithm}",created="{unixTimestamp}",expires="{unixTimestamp}",  headers="{signedHeaders}",signature="{base64Signature}" ```  | Attribute | Description | |-----------|-------------| | `keyId` | `{subscriberId}|{uniqueKeyId}|{algorithm}` — FQDN, registry UUID, algorithm | | `algorithm` | MUST be `ed25519` | | `created` | Unix timestamp when the signature was created | | `expires` | Unix timestamp when the signature expires | | `headers` | Space-separated signed headers. MUST include `(created)`, `(expires)`, `digest` | | `signature` | Base64-encoded Ed25519 signature over the signing string |  Signing string: `(created): {value}
(expires): {value}
digest: BLAKE-512={digest}` where `digest` is a BLAKE2b-512 hash of the request body, Base64-encoded.