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100 lines
4.3 KiB
Markdown
100 lines
4.3 KiB
Markdown
# Interesting things about the new auth ticket
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Firstly, why do you need to use the new auth ticket?
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Well, thats because some Emulators, or servers checking inside the tickets. (Example is Nemirtingas Epic Emu)\
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Old version of the ticket not gonna work with them.
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## How does the old ticket look vs the new?
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Old Ticket looks like this:
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```
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4 byte (header) | 4 byte | 8 byte
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0x14 (AKA 20) 00 00 00 | [TicketNumber] | [SteamId]
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```
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As you see the ticket doesnt contains any information when its made, what DLC you have and appid you started.
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### Before seeing how the new ticket looks, what does the "HasGC" means?
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GC means Game Coordinator.\
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It helps with IP address, better matchmake, and other things.
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Why do we use it?\
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Well simple because I researched for it and everything usually sending that data back.\
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You can write a simple Application and edit steam_api.txt for any appid you own and gather the ticket from it.
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GC contains these infromation:
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```c++
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uint32_t STEAM_APPTICKET_GCLen = 20; // Magic header 20
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uint64_t GCToken{}; // A unique token for this, can be random or sequential
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CSteamID id{}; // our steamId
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uint32_t ticketGenDate{}; //epoch time when generated
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uint32_t STEAM_APPTICKET_SESSIONLEN = 24; // Magic Header 24
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uint32_t one = 1; // dont know yet
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uint32_t two = 2; // dont know yet
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uint32_t ExternalIP{}; // External ip (Steam usually encrypting these)
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uint32_t InternalIP{}; // Internal ip (Steam usually encrypting these)
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uint32_t TimeSinceStartup{}; // Seconds since Steam Startup
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uint32_t TicketGeneratedCount{}; // how many ticket did you generated since startup
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uint32_t FullSizeOfGC = 56; // GC size (52) + 4
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```
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If you add those together you get 52
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```
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8 = uint64_t
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4 = uint32_t
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4 + 8 + 8 + 4 = 24 (4 without the header is 20 so the lenght of the Next section)
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4 + 4 + 4 + 4 + 4 + 4 + 4 = 28 (4 without the header is 24 so the lenght of the Next section)
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```
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Yes, we could separate these but since only GC doing this, that is not much
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### The rest of the Ticket
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As you see in the auth.h file the ticket is contains these infromation:
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```c++
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uint32_t TheTicketLenght; // Full lenght of the ticket exluding the padding and the Singature
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uint32_t Version{}; // Latest version is 4 so we keep that way
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CSteamID id{}; // our steamId
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uint32_t AppId{}; // Current AppId that we playing
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uint32_t ExternalIP{}; // External ip (Steam usually encrypting these)
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uint32_t InternalIP{}; // Internal ip (Steam usually encrypting these)
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uint32_t AlwaysZero = 0; //OwnershipFlags? or Might be VAC Banned?
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uint32_t TicketGeneratedDate{}; // Epoch Seconds when the Ticket generated
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uint32_t TicketGeneratedExpireDate{}; // Epoch Seconds when the Ticket will expire
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std::vector<uint32_t> Licenses{}; // our licenses (Usually is 0 or if you own a locked beta that will be it)
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std::vector<DLC> DLCs{}; // what DLC we own
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```
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The DLC data inside:
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```c++
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struct DLC {
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uint32_t AppId{}; // AppId of the DLC
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std::vector<uint32_t> Licenses{}; // Again license what you own, usually 0 or nothing inside
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};
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```
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The Licenses:\
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All app if not relesed to public is behind a license, steam usually set (or returns) 0 as if you own it or doesnt have any license to it.\
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IT DOES not mean the app is free, even if you bought it still shown as 0!
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### Signature and padding.
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I dont know why steam has a 2 byte for a padding but that could be something or a random value.\
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OR that could be if we got banend by VAC? I dont know yet.
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Steam has a signature, as I seen its a 128 lenght one. I choosen RSA1 and PKCS1 since it giving me that one.\
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I generated a key (You can get yourself here: https://github.com/Detanup01/stmsrv/blob/main/Cert/AppTicket.key) or from Auth.cpp/h file.
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It is just we get the ticket data as bytes and we sign it with our key, and vola we have a ticket!
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Thats why the NEW size is Minimum 170 because 128 + 42 (Minimum Ticket Data without any DLC, License, and GC)
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## Interesting things
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The Ticket can exceed 1024 byte if user own soo many DLC. Steam recommend setting as 1024 but I recommend everyone using 2048 if you have a Game that has many DLC. (PayDay 2)
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Old ticket is similar to the start of our GC ticket.
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Currently SendUserConnectAndAuthenticate, beginAuth "does not" have code for supporting NEW AuthTicket. But because the Old ticket header is similar to GC which we do send data with my steamId and a random Id. It doesnt need to Deserialize anything from the ticket. |