matrix-spec/api/server-server/examples/server_key_notary_signed.json

{
    "$ref": "server_key.json",
    "signatures": {
        "example.org": {
            "ed25519:abc123": "VGhpcyBzaG91bGQgYWN0dWFsbHkgYmUgYSBzaWduYXR1cmU"
        },
        "notary.server.com": {
            "ed25519:010203": "VGhpcyBpcyBhbm90aGVyIHNpZ25hdHVyZQ"
        }
    }
}