This dll invokes some external functions contained in another dll (which I suppose has been written in c++, considering the DllImport etc present in the source code) with all the real hash logic and methods... and here comes the problem.
I've not been able to find and locate that dll: no trace in the folder at all.

Use Process Explorer or Process Hacker to find which modules are loaded in the address space of the process. When you find the required dll, check whether there exists a valid path for that module in disk. If there is one then you may simple copy over the dll for further analysis. Otherwise the dll may have been loaded from memory. In such case you have to dump that dll from memory.

Next using a PE detection tool such as ExeInfo PE , Detect It Easy scan the dll. If it is a managed DLL (aka .net) check if a .net decompiler such as dotPeek or reflector can decompile it readily. If it is obfuscated, try using de4dot before decompiling.

If it is a native dll IDA Pro is your best option for analyzing the dll.

There are quite a few ways to package a dll inside an executable.

• For native dlls to be embedded inside native executables, you can simply store them as resources, which will be written to disk at runtime and loaded subsequently. Another way is to load it completely from memory as said previously.
• For native dlls to be embedded inside managed executables, you can use the resource method.
• For managed dlls to be embedded inside managed executables, you may use the resource method, but writing it to disk is not needed.

See this article on loading a dll from embedded resource for more info.

This dll invokes some external functions contained in another dll (which I suppose has been written in c++, considering the DllImport etc present in the source code) with all the real hash logic and methods... and here comes the problem.
I've not been able to find and locate that dll: no trace in the folder at all.

Use Process Explorer or Process Hacker to find which modules are loaded in the address space of the process. When you find the required dll, check whether there exists a valid path for that module in disk. If there is one then you may simple copy over the dll for further analysis. Otherwise the dll may have been loaded from memory. In such case you have to dump that dll from memory.

Next using a PE detection tool such as ExeInfo PE , Detect It Easy scan the dll. If it is a managed DLL (aka .net) check if a .net decompiler such as dotPeek or reflector can decompile it readily. If it is obfuscated, try using de4dot before decompiling.

If it is a native dll IDA Pro is your best option for analyzing the dll.

There are quite a few ways to package a dll inside an executable.

• For native dlls to be embedded inside native executables, you can simply store them as resources, which will be written to disk at runtime and loaded subsequently. Another way is to load it completely from memory as said previously.
• For native dlls to be embedded inside managed executables, you may use the resource method.
• For managed dlls to be embedded inside managed executables, you may use the resource method, but writing it to disk is not needed.

See this article on loading a dll from embedded resource for more info.

This dll invokes some external functions contained in another dll (which I suppose has been written in c++, considering the DllImport etc present in the source code) with all the real hash logic and methods... and here comes the problem.
I've not been able to find and locate that dll: no trace in the folder at all.

Use Process Explorer or Process Hacker to find which modules are loaded in the address space of the process. When you find the required dll, check whether there exists a valid path for that module in disk. If there is one then you may simple copy over the dll for further analysis. Otherwise the dll may have been loaded from memory. In such case you have to dump that dll from memory.

Next using a PE detection tool such as ExeInfo PE , Detect It Easy scan the dll. If it is a managed DLL (aka .net) check if a .net decompiler such as dotPeek or reflector can decompile it readily. If it is obfuscated, try using de4dot before decompiling.

If it is a native dll IDA Pro is your best option for analyzing the dll.

This dll invokes some external functions contained in another dll (which I suppose has been written in c++, considering the DllImport etc present in the source code) with all the real hash logic and methods... and here comes the problem.
I've not been able to find and locate that dll: no trace in the folder at all.

Use Process Explorer or Process Hacker to find which modules are loaded in the address space of the process. When you find the required dll, check whether there exists a valid path for that module in disk. If there is one then you may simple copy over the dll for further analysis. Otherwise the dll may have been loaded from memory. In such case you have to dump that dll from memory.

Next using a PE detection tool such as ExeInfo PE , Detect It Easy scan the dll. If it is a managed DLL (aka .net) check if a .net decompiler such as dotPeek or reflector can decompile it readily. If it is obfuscated, try using de4dot before decompiling.

If it is a native dll IDA Pro is your best option for analyzing the dll.

There are quite a few ways to package a dll inside an executable.

• For native dlls to be embedded inside native executables, you can simply store them as resources, which will be written to disk at runtime and loaded subsequently. Another way is to load it completely from memory as said previously.
• For native dlls to be embedded inside managed executables, you can use the resource method.
• For managed dlls to be embedded inside managed executables, you may use the resource method, but writing it to disk is not needed.

See this article on loading a dll from embedded resource for more info.