Onion Address
The human-readable hostname of an onion service (v3: 56 characters ending in .onion). It encodes the service public key.
A v3 onion address is 56 characters long because it is not a name but a key: the string encodes the service’s ed25519 public key, a checksum, and a version byte in base32. Whoever connects to the address is cryptographically guaranteed to reach the holder of the matching private key — no certificate authority is involved.
Why the length is the point
The checksum catches typos, and the key length puts forgery computationally out of reach. What attackers can do is generate a vanity address that matches the first few characters of a known service. Since nobody memorizes 56 characters, a quick glance at the prefix is exactly the check that fails.
The real weak point
The cryptography authenticates the endpoint, not the choice of endpoint. Phishers exploit the moment an address is copied: a lookalike string in a directory, forum post, or search result. The reliable habit is to take an address once from a verified primary source and bookmark it — background in Onion Service v3 and Phishing.
Category: Network