In fact, the trap in your EXE is no more related to that call...
To debug the trap:
run it with your preferred debugger... It will break at
Code:
004699E0 mov byte ptr [esi],dl
where ESI is 514808
If you look at program memory map
(for example through Process Hacker), you will see that memory 514000-51D000 (presumably allocated by LMCRYPT,
look at memory content in the debugger) is read-only!
Hence the trap due to Access Violation.
Best regards, bilbo