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+--- Thread: Anti-virus and rsa4.dll (/showthread.php?tid=2562)
Anti-virus and rsa4.dll - Spadie - Thursday, May 27th, 2021
The Lineage 2 client uses the "RSA algorithm" for public-key cryptography. When they created the client they choose to have it dynamically linked to Windows system files and not create their own file and have it dynamically linked or make it static linked.
Once Windows Vista came out, Microsoft changed how they designed the system and does not have the previously FIPS-140-1 validated Microsoft Base Cryptographic Provider. But we were able to use Windows XP files in the client for it to work.
But an issue came in Windows 7 and later (need for the patcher) as it does not have all the same version of some of the needed files. Windows 7 also blocks the use of old files and also if the file is already loaded it reads it from the memory and does not force a new local reload/read.
The patcher was made (currently outdated and no longer used) to patch files in the system so it would force read it when loading the client, so it would be able to open. After the client is open the user can just unpatch. I made it so when you unpatch the system is running pure as if it was never patched.
Enter rsa4.dll, which is from Windows 9x, in our case we use the Windows ME version. Due to that the file is so old and does not exist on Windows 2000/XP/Vista/7/8 etc... We are able to use this file to load the client without a "patcher".
The goal of using rsa4.dll is so the RSA key for lineage2 works properly so the client is able to open. It is only used to load/open the client.
Due to using an old file that runs "Microsoft Base Cryptographic" This deals with the "Cryptographic Boundary" as some anti-virus scanners will try to block it since the Data Protection API of Microsoft Windows 7 is not part of the module (as are just running the DLL file alone, and it is old) it is considered to be outside the boundary and triggers the anti virus software.
RE: Anti-virus and rsa4.dll - Spadie - Thursday, May 27th, 2021
This is repost from October 29th 2012 11:44 AM.