This is a typical Tox ID that you currently give out to friends. It is a public key, nospam value, and checksum concatenated in hexadecimal format. The result is the 76-character string shown above.
(The three parts of the a Tox ID.)
The public key is internally generated from the crypto_box_keypair function
by NaCl.
This is explained better here. In the current implementation of NaCl, it is 32 bytes (64 hexadecimal characters).
In practice, libtoxcore.so generates a new random public/private keypair during initialization and it's up to you to save this identity (tox_save()) or replace it with a previously saved one (tox_load())
The nospam value is a randomly generated number appended to the
key. A friend request sent without knowing the correct nospam
value will be ignored.
The nospam value can be changed at any time without affecting
the public key, stopping all requests to your current ID. This makes
it effective for fighting spam (its original purpose!).
The checksum is a simple XOR checksum of the public key and
nospam value. It is used to to quickly verify the integrity
of the Tox ID.
Because Tox has no central servers, you will need to know someone who is already "in" the network before you can successfully connect your client.
The Tox core handles this in one of two ways:
- Automatically bootstrapping to a Tox client that it finds on the LAN, and
- Bootstrapping to a known peer that your code provides.