All requests need to be signed following the HTTP Signatures specification using your ED25519 key set. Each request must have Date header. Request with a body like POST and PUT requests, must have a Content-Type and Digest header. The (request-uri) must also be part of the signature.
The KeyId must be the base58 encoded public ED25519 key. The algorithm may be either ed25519 or ed25519-sha256. If you use the the SHA-256 version, the signature string needs to be hashed. The signature must be base64 encoded as required by the http signatures specifications.
The HTTP signature string is only constructed from the HTTP headers, not the body. To make sure the body hasn't been manipulated, requests are required to have a Digest header as described in RFC 3230. The digest needs to be a SHA-256 hash.
Note that the Digest header, is a different specification than HTTP Digest Authentication.