The jsonwebtoken accept strings as input for secrets which is
nonsensical from a cryptographic standpoint as the algorithms all
operate on byte sequences. Worse still, strings are encoded into bytes
using UTF-8, which disallows certain sequences of bytes from appearing
and potentially weakening the cryptography.
For legacy reasons the master secret was encoded into base64 _and passed
as a string to jsonwebtoken_. This further weakened the crypto as the
bytes that can appear in base 64 is only 1/4 of the 256 possible values
for bytes. This could significantly weaken the cryptographic strength
of the tokens.
I have known of this issue for quite some time but has put off actually
fixing it for too long now. Since the master secret is already
documented as being in base 64, decode it as base 64 and pass it as a
byte Buffer to jsonwebtoken. This will ensure every byte value is
possible in the byte sequence passed to the jsonwebtoken crypto.
The impact of this change is unfortunately that all tokens will become
invalid and will have to be reissued.
Add authentication plugin that does a simple challenge response protocol
to verify that the player trying to log in is who they claim to be. The
process goes as follows:
1. A player code is generated for a player that wants to log in and is
displayed in-game.
2. The player code is input into the web interface and the master
generates a verification code as a challenge back along with a token.
3. The player inputs the verification code in-game and is logged in to
the web interface in doing so.
To do the actual login the web interface polls a verify endpoint every 2
seconds until the code has either been verified or expired. The
challenge comes from being unable to control the verification code and
having to input it as a player logging into one of the servers in order
to login.
Some additional steps are taken in order to increase the difficulty for
an attacker to subvert the challenge:
- The login process must be started from in-game.
- Generated codes are only valid for a limited timespan which is
configurable and 2 minutes by default.
- The verification code comes with a token that only works with one
player code and verification code combo and must be provided to pass
validation.
Hornwitser