Signed vs unsigned addons? what does it mean?

[thedudesam 10]

Hi i see some addons on armaholic and some say signed - no and some say signed - yes.

What does this mean?

[PuFu 4591]

Hi i see some addons on armaholic and some say signed - no and some say signed - yes.

What does this mean?

exactly what it says...The ones marked as signed, have the bisign files as well, which are the signature files for the pbo, which usually also comes with a public key so that server admins can allow or not certain addons on their servers.

more info here, and i suggest you start using the search function on those forums or wiki next time:

http://community.bistudio.com/wiki/ArmA:_Addon_Signatures

[thedudesam 10]

Ahh thanks dude.

So i can host a server using unsigned addons (such as vehicles) and providing the people joining have it also, they will work?

[walker 0]

Hi thedudesam

The concept of signed addons is to prevent cheating and game-breaking/hacking as well as prevent incompatible addons causing the server or clients to crash.

In the case of a server running unsigned vehicle addons it would be possible to run a cheat or hack hidden in the unsigned content.

Or run an addon on one client that has say a collision between a vehicle and the wall taking place on the server and all other clients but not on the culprit client, thus causing a sychronisation error. Worse still a bullet might pass through the object in one client and in the server and other clients dammage the vehicle causing it to explode destroying other objects and entities thus creating a cascading error. Or the vehicle might have have 3 crew and 7 cargo spaces in one client and 4 crew and 13 cargo places in the rest and the server; such a discrepancy would probably cause server and clients crash. More subtle things might also cause a memory leak.

The server could laboriously check every single file in the addons comparing every byte of data for every addon on every client and the old checkfiles command in the config used to do this but a moments thought tells you that is going to take for ever with a mod the size of say ACE.

So the solution was to make a public private key check-sum for the files this is much smaller. Altering the addon alters the signature an addon would produce. This is more or less the same technology concept as is used to protect online banking transactions so it is very secure.

It only takes a second to check as it is a secret calculation of a check-sum that is checked not each byte of the addon and is actually more secure than checking every byte.

Thus in the case of a server with signature check turned on then only people with addons that match the keys can join the server.

So think of it as a passport and baggage check at the entrance to the airport.

To turn signature checking on you use verifySignatures=1.

Kind Regards walker

Edited January 10, 2010 by walker

[emerald 8 10]

Captain Walker,

i have been denied access to play because of these files. Do you happen to know a easy way to delete them?

[jedra 11]

If you are denied access to a server because your signature check failed, it means one of three things really;

1. You are using a MOD that the server admin has not allowed. In this case you must run without that mod to play on the server. Just remove it from the -mod= switch, or remove it from the preset if you are using SixUpdater.

2. You are using a MOD that has an outdated key. In this case you need to download the latest version of the mod and key (usually they are together).

3. The server is using an older version of the mod than you are. In this case you can either contact the server admin and try and get the same version from somewhere or ask him to update the mod on the server. Most likely in this case you will need to pick another server.