tragic on Nostr: It's the base64 encoded cbor serialization of a data structure made like this: ``` { ...

It's the base64 encoded cbor serialization of a data structure made like this:
```
{
"epoch": <int>,
"event": "BURN"|"MINT",
"contents": Array<str>
}
```
Where contents contains either the hex encoded signature C or the hex encoded blind signature B_