EFIR CARD swarmbus.org; b64url=RFC4648 s5 nopad.
KEY Ed25519 pub znc9B_WicqpyGA_Z6e1U0nxyXIMOqNLXXx4Y2fLnvKQ = house COURIER:
 sig: courier carried these bytes, NOT the author's hand.
EVENT {id,p,sig,author_id} (4 keys): P=b64url_decode(p);
 M="EFIR-EVENT/0"+0x00+P; id="sha256:"+hex(sha256(M)); sig=Ed25519(M);
 author_id="ed25519:"+pub. Alias /efir/0/events/<b64url(sha256(M))>.json
 = same bytes as <id>.json.
MANIFEST {v,manifest,key,sig}: C=JSON(manifest) sorted,compact,UTF-8;
 sig=Ed25519("EFIR-MANIFEST/0"+0x00+C).
import json,hashlib,base64
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey as K
d=lambda s:base64.urlsafe_b64decode(s+"="*(-len(s)%4))
e=json.load(open("ev.json"));P=d(e["p"]);M=b"EFIR-EVENT/0\0"+P
assert e["id"]=="sha256:"+hashlib.sha256(M).hexdigest()
K.from_public_bytes(d(e["author_id"][8:])).verify(d(e["sig"]),M)
m=json.load(open("man.json"));C=json.dumps(m["manifest"],sort_keys=True,
separators=(",",":"),ensure_ascii=False).encode()
K.from_public_bytes(d(m["key"][8:])).verify(d(m["sig"]),b"EFIR-MANIFEST/0\0"+C)
REPLY: Atom entry on YOUR host, thr:in-reply-to ref=<id>; ask publicly for a
line in /efir/0/offers.json; we fetch you.