Function at 0x873a60
Capabilities:
Encrypt data using rc4 via winapi
Get file size
Hash data via wincrypt
Hash data with md5
Initialize hashing via wincrypt
Read file on windows

Disassembly:
push ebx
mov eax, dword [esp + 8]
push ebp
push esi
push edi
push 0
push 0x80
push 3
push 0
push 3
push 0x80000000
mov ebp, ecx
push eax
call dword [sym.imp.kernel32.dll_CreateFileA]
mov esi, eax
cmp esi, 0xffffffff
jne 0x873a9a
pop edi
mov dword [ebp + 0x44], 1
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
push 0
push esi
call dword [sym.imp.kernel32.dll_GetFileSize]
cmp eax, 0xffffffff
mov dword [ebp + 0x24], eax
jne 0x873ac2
push esi
call dword [sym.imp.kernel32.dll_CloseHandle]
pop edi
mov dword [ebp + 0x44], 0xb
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov eax, dword [ebp + 4]
test eax, eax
je 0x873ad9
push eax
call fcn.0087aa78
add esp, 4
mov dword [ebp + 4], 0
mov ecx, dword [ebp + 0x24]
push ecx
call fcn.0087ab61
add esp, 4
mov dword [ebp + 4], eax
test eax, eax
jne 0x873b03
push esi
call dword [sym.imp.kernel32.dll_CloseHandle]
pop edi
mov dword [ebp + 0x44], 2
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov ecx, dword [ebp + 0x24]
lea edx, [esp + 0x14]
push 0
push edx
push ecx
push eax
push esi
call dword [sym.imp.kernel32.dll_ReadFile]
mov eax, dword [ebp + 0x24]
mov ecx, dword [esp + 0x14]
cmp ecx, eax
je 0x873b38
push esi
call dword [sym.imp.kernel32.dll_CloseHandle]
pop edi
mov dword [ebp + 0x44], 3
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov edx, dword [ebp + 4]
lea ecx, [ebp + 0x28]
mov edi, ecx
lea edx, [edx + eax - 0x10]
mov ebx, dword [edx]
mov dword [edi], ebx
mov ebx, dword [edx + 4]
mov dword [edi + 4], ebx
mov ebx, dword [edx + 8]
mov dword [edi + 8], ebx
mov edx, dword [edx + 0xc]
mov dword [edi + 0xc], edx
mov edx, dword [ecx]
cmp edx, 0x32812622
jne 0x873b8c
cmp dword [ebp + 0x34], 0x32812621
jne 0x873b8c
mov ecx, dword [ebp + 0x2c]
mov edx, dword [ebp + 0x30]
mov edi, eax
mov byte [ebp + 0x1c], 1
lea edx, [edx + ecx + 0x10]
mov dword [ebp + 0x38], ecx
sub edi, edx
mov dword [ebp + 0x20], edx
mov dword [ebp + 8], edi
xor ebx, ebx
jmp 0x873baa
xor eax, eax
xor ebx, ebx
mov dword [ecx], eax
mov dword [ecx + 4], eax
mov dword [ecx + 8], eax
mov dword [ecx + 0xc], eax
mov eax, dword [ebp + 0x24]
mov byte [ebp + 0x1c], bl
mov dword [ebp + 0x20], ebx
mov dword [ebp + 8], eax
mov dword [ebp + 0x38], ebx
cmp eax, dword [ebp + 0x20]
jae 0x873bbe
mov byte [ebp + 0x1c], bl
mov dword [ebp + 0x20], ebx
mov dword [ebp + 0x24], ebx
mov dword [ebp + 8], ebx
mov dword [ebp + 0x38], ebx
push esi
call dword [sym.imp.kernel32.dll_CloseHandle]
cmp dword [ebp], ebx
jne 0x873bf2
push 0xf0000000
push 1
push 0x96de70
push ebx
push ebp
call dword [sym.imp.advapi32.dll_CryptAcquireContextA]
test eax, eax
jne 0x873bf2
pop edi
mov dword [ebp + 0x44], 4
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov eax, dword [ebp + 0x40]
lea esi, [ebp + 0x40]
cmp eax, ebx
je 0x873c05
push eax
call dword [sym.imp.advapi32.dll_CryptDestroyHash]
mov dword [esi], ebx
mov ecx, dword [ebp]
push esi
push ebx
push ebx
push 0x8003
push ecx
call dword [sym.imp.advapi32.dll_CryptCreateHash]
test eax, eax
jne 0x873c2b
pop edi
mov dword [ebp + 0x44], 5
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov edx, dword [esp + 0x20]
or ecx, 0xffffffff
mov edi, edx
xor eax, eax
repne scasb al, byte es:[edi]
not ecx
dec ecx
push ebx
push ecx
push edx
mov edx, dword [esi]
push edx
call dword [sym.imp.advapi32.dll_CryptHashData]
test eax, eax
jne 0x873c5b
pop edi
mov dword [ebp + 0x44], 6
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov eax, dword [ebp + 0x3c]
lea edi, [ebp + 0x3c]
cmp eax, ebx
je 0x873c6e
push eax
call dword [sym.imp.advapi32.dll_CryptDestroyKey]
mov dword [edi], ebx
mov eax, dword [esi]
mov ecx, dword [ebp]
push edi
push ebx
push eax
push 0x6801
push ecx
call dword [sym.imp.advapi32.dll_CryptDeriveKey]
test eax, eax
jne 0x873c96
pop edi
mov dword [ebp + 0x44], 7
pop esi
pop ebp
xor al, al
pop ebx
ret 0x10
mov eax, dword [ebp + 8]
mov edx, dword [ebp + 4]
push eax
push edx
mov ecx, ebp
call fcn.00873d10
test al, al
jne 0x873cb7
pop edi
mov dword [ebp + 0x44], 0x58
pop esi
pop ebp
pop ebx
ret 0x10
mov ecx, dword [ebp + 8]
mov eax, dword [esp + 0x1c]
cmp eax, ecx
jbe 0x873cc4
mov eax, ecx
mov edx, dword [esp + 0x18]
mov esi, dword [ebp + 4]
mov ecx, eax
mov edi, edx
mov ebx, ecx
shr ecx, 2
rep movsd dword es:[edi], dword [esi]
mov ecx, ebx
and ecx, 3
rep movsb byte es:[edi], byte [esi]
mov byte [edx + eax], 0
mov eax, dword [ebp + 4]
test eax, eax
je 0x873cf8
push eax
call fcn.0087aa78
add esp, 4
mov dword [ebp + 4], 0
pop edi
pop esi
pop ebp
mov al, 1
pop ebx
ret 0x10