I have written two programs that encrypts and sends and decrypts and receives a text file in asm. The program works fine, the problem I'm having is setting up the com1 port. The transmitter sends the file fine, but the receiver cannot receive the file until i have set up the comm port with hyper terminal on defaults. Once hyper terminal has been set up and exited the receiver will receive the file no problem. I have tried setting up hyperterminal and the using the exact same settings from the DCB structure in my program but it made absolutely no difference. Watever i do the only thing that continues to work is hyperterminal. Am i missing some very imoprtant step here.
This is just introducing me to programming so i know that most of the code is far from perfect, the main thing I want to do is just get rid of the hyper terminal step so it can be a one click interaction with the pc.
Here is my original code for setting up the comm port on both machines as it stands now after reverting all attempts to make it work(copying DCB exactly).
#include <windows.h>
#include <tchar.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
TCHAR *pcCommPort = TEXT("COM1");
hCom = CreateFile( pcCommPort,
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // default security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // not overlapped I/O
NULL // hTemplate must be NULL for comm devices
);
if (hCom == INVALID_HANDLE_VALUE)
{
// Handle the error.
printf ("CreateFile failed with error %d.\n", GetLastError());
return (1);
}
// Build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm.
SecureZeroMemory(&dcb, sizeof(DCB));
dcb.DCBlength = sizeof(DCB);
fSuccess = GetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
}
// Fill in DCB: 9,600 bps, 8 data bits, no parity, and 1 stop bit.
dcb.BaudRate = CBR_9600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit
fSuccess = SetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
}
_tprintf (TEXT("Serial port %s successfully reconfigured.\n"), pcCommPort);
CloseHandle(hcom);
return (0);
}And this is the code for the reciever itself.
/* File receiver/decrypter for transmitter.exe written in asm86 that decrypts a text output sent over com1
*/
#include <stdio.h>
#include <conio.h>
#include <windows.h>
#define FEND 0xFF
int main(void)
{
char wmode[] = "wb";
char rmode[] = "rb";
char filename[255];
char filepath[]="\nType the full filepath and filename of where you would like to save the file.\n->";
char portname[] = "COM1";
char error[] = "\nFile has failed to open\n";
char error1[] = "\nThe com port has failed to open\n";
char success[] = "\nFile opened succesfully\n"; //success and error messages for opening com ports
char success2[] ="\nCom port opened succesfully\n";
char recieved[] = "\nFile received\n";
char requestkey[] = "Please Enter 8 character passkey\n->";
char scanparam[] = "%8s";
char scanparam1[] = "%255s";
int password[8];
FILE * fileptr;
FILE * portptr;
__asm
{
/*get file path*/
lea eax, filepath //load effective address of filepath string
push eax //push onto stack
call DWORD PTR (printf) //call printf, using filepath as parameter.
add esp,4 //scrub stack
lea eax, filename //load address of character array password
push eax //push onto stack
lea eax, scanparam1 //load address of scanparam to general register
push eax //push to stack
call DWORD PTR (scanf) //call scanf with using values pushed to stack
add esp,8 //scrub from stack
/*get password*/
lea eax, requestkey //load effective address of requestkey string
push eax //push onto stack
call DWORD PTR (printf) //call printf, using requestkey as parameter.
add esp,4 //scrub call off stack
lea eax, password //load address of character array password
push eax //push onto stack
lea eax, scanparam //load address of scanparam to general register
push eax //push to stack
call DWORD PTR (scanf) //call as paramater to scanf
add esp,8 //scrub from stack
/*declare file write mode and open*/
lea eax,wmode //load effective address of wmode into eax
push eax //push to stack
lea eax,filename //load effective address of filename
push eax //push to stack
call DWORD PTR (fopen) //open data file for reading with parameters wb and chosen filename
add esp,8 //scrub parameters from stack
mov ebx, eax //mov eax to ebx so it can be store in filepointer later
or eax,eax //check fopen has returned a value to show succes
jnz fileOpened //jump to fileOpened if not zero
lea eax,error //print error and jump to endit
push eax
call printf
add esp, 4
jmp endit
fileOpened: lea eax, success //load effective address of success string
push eax //push onto stack
call DWORD PTR (printf)//call printf, using requestkey as parameter.
add esp,4 //scrub call of stack
mov DWORD PTR(fileptr),ebx //put value returned by fopen into filept
lea eax, rmode //load read address mode into eax
push eax //push onto stack
lea eax,portname //load portname and push onto stack
push eax
call DWORD PTR (fopen) //using parameters pushed onto stack open com port
add esp,8 //scrub parameters from stack
or eax,eax //check that file has been succesfully opened (returns value not null)
jnz portOK //jump to port ok
lea eax,error1 //load address of error one and push onto stack
push eax
call DWORD PTR (printf) // call function print f and print error1
add esp,4 //scrub stack
mov eax,DWORD PTR(fileptr) //move fileptr to eax then push to stack
push eax
call DWORD PTR(fclose) // call function fclose with parameter file pointer
add esp,4 // closing file then jump to endit
jmp endit
portOK: mov DWORD PTR(portptr),eax//store addres of comport in portptr
lea eax, success2 //load effective address of requestkey string
push eax //push onto stack
call DWORD PTR (printf) //call printf, using requestkey as parameter.
add esp,4 //scrub call off stack
mov ebx,0 //set ebx to zero for decrypt counter loop
mov ecx,0 //set ecx to 0 for EOF character loop
more: push ecx //push ecx to stack so it remains unchange by fgetc
mov eax, DWORD PTR(portptr) //move com port address to eax
push eax //push to stack
call DWORD PTR(fgetc) //call fgetc with com port address as parameter to get character from com port
add esp,4 //scrub stack
pop ecx //pop eof loop counter off of stack
cmp al, FEND //cmp recieved hex character to FEND
jz endofile //If zero(the same) jump to endofile
cmp ecx,0 //compare eof counter to zero
jz more1 //if not zero dec 1, if zero skip(so does not become minus)
dec ecx //this step is skipped each time eof
more1: push ecx /push ecx to stack so it can be freely used by deCrypt
mov ecx, ebx //move deCrypt counter to ecx
mov ebx, eax //move character retrieved by fgetc to ebx
call deCrypt
/*write*/
mov eax, DWORD PTR(fileptr) //mov filepointer to eax
push ecx //push ecx(nowdecrypt loop counter) to stack so not lost by function call
push eax //push file address and character to stack to be used by fputc
push ebx
call DWORD PTR(fputc)
add esp,8 //scrub the parameters from stack
pop ebx //push decrypt loop counter to ebx
pop ecx //push eof counter to ecx
jmp more //return to begining of more with incremented count values
deCrypt:
cmp ecx,1 //perform rotate on first 4 characters of password then
ja decrypt2 // use first character to xor with character from com port
rol password[0], 8 // Do this until decrypt count is 2
mov edx, password[0] // when deCrypt is called and counter is already 3 skip to decrypt2
xor bl, dl
add ecx,1
ret //return to where function was called from
decrypt2:
cmp ecx,3 // same as deCrypt but rotate characters 2-5 until count is 4
ja decrypt3//when deCrypt2 is called and counter is already 4 skip to decrypt3
rol password[2], 8
mov edx,password[2]
xor bl, dl
inc ecx
ret //return to where function was called from
decrypt3:
inc ecx //same as previous but for characters 4-7
rol password[4],8// performs rotate and xor until ecx = 7
mov edx,password[4]
xor bl,dl
cmp ecx,7 //if ecx is not 7 skip return to 0 step
jb decrypt4
mov ecx, 0 //when ecx is 7 return counter to 0
decrypt4:
ret // return to where function was call from
endofile:
inc ecx //increment eof loop counter
cmp ecx, //return to more1 until eof character found 4 consequetive times(reduce chance of incorrect exit to negligle)
jnz more1
finished: lea eax,recieved // display file recieved message
push eax
call DWORD PTR printf
add esp,4
mov eax, DWORD PTR(fileptr) // close the file
push eax
call DWORD PTR(fclose)
add esp,4
mov eax, DWORD PTR(portptr) //close the com port
push eax
call DWORD PTR(fclose)
add esp,4
push 5000//wait for 5 seconds before program close so messages can be seen,(for if not running from command prompt.)
call DWORD PTR(Sleep)
endit:
xor eax, eax //clear all general registers
xor ebx, ebx
xor ecx, ecx
xor edx, edx
} //asm
return 0;
} // main[}