/*
crypt.c
written by Ben Fasenfest
on: 11/22/96
Encrypts / decrypts files with a password
*/
#include
#include
#include "ansi.c"
char menu(); /* displays main menu and returns choic */
int take_action(char choice); /* I changed take_action to return a value so
that the program can exit from the main()
function or loop back to the main menu
I assumed that this had to be or else there
would not be a quit function on the menu */
unsigned int code(void); /*prompts for password and returns code value */
unsigned char crypt(unsigned char in, char mode, unsigned char codefactor);
/*the actual encryption function */
void aprint(char *what, int attrib); /* takes a character string and prints
it to the screen with an attribute */
void header(void); /* prints the header to the top of each screen */
FILE *file=NULL, *ofile=NULL;
int main(void)
{
char choice;
int ret;
do {
choice=menu();
fcloseall();
}
while((ret=take_action(choice)) !=0);
if(isansi()==1)
ansi_clrscrn();
printf("Thankyou for using\nNSCRYPT File encrypter / decrypter\n\tCopyright 1996 by NebSoft Inc.\n\tWritten by Ben Fasenfest.\n");
return ret;
}
char menu()
{
char rc;
header();
printf("\t\t------------MAIN MENU------------");
printf("\n\n\t\t\ta) encrypt a file\n\t\t\tb) decrypt a file\n\t\t\tc) quit");
printf("\n\n\t\tPlease enter your choice --> ");
do
{
rc=getche();
if(rc!='a' && rc!='b' && rc!='c')
printf("\n\n\t\tThat is not a choice.\n\t\tPlease enter your choice --> ");
}
while(rc!='a' && rc!='b' && rc!='c');
return rc;
}
int take_action(char choice)
{
char iname[50];
char oname[50];
unsigned char ch;
int c, ret=1;
unsigned int cd;
if(choice=='a')
{
header();
printf("What is the name of the file to encrypt ? ");
fflush(stdin);
scanf("%s", iname);
if((file=fopen(iname,"r")) !=NULL)
{
cd=code();
printf("\n\nDo you want the encrypted file\n\n\ta) saved to another file\n\tb) printed on the screen");
do {
printf("\n\nEnter your choice --> ");
ch=getche();
if(ch!='a' && ch!='b')
printf("\nThat is not a choice.");
}
while(ch!='a' && ch!='b');
if(ch=='a')
{
printf("\n\nPlease enter the name of the file to save to --> ");
fflush(stdin);
scanf("%s",oname);
if((ofile=fopen(oname,"w"))!=NULL)
{
while((c=getc(file)) !=EOF)
{
fprintf(ofile, "%c", crypt(c, 'e', cd));
}
printf("\n\nFile %s encrypted and saved as %s\n",iname,oname);
}
else {
printf("\n\nThe file %s cannot be written to.\n", oname);
}
}
else {
printf("\n");
while((c=getc(file)) !=EOF)
{
ch=crypt(c,'e',cd);
if(ch!=7) /* 7 is the bell - really annoying */
printf("%c", ch);
}
printf("\n\n");
}
}
else
printf("\n\nThe file %s cannot be found.\n", iname);
}
else if(choice=='b')
{
header();
printf("What is the name of the file to decrypt ? ");
fflush(stdin);
scanf("%s", iname);
if((file=fopen(iname,"r")) !=NULL)
{
cd=code();
printf("\n\nDo you want the decrypted file\n\n\ta) saved to another file\n\tb) printed on the screen");
do {
printf("\n\nEnter your choice --> ");
ch=getche();
if(ch!='a' && ch!='b')
printf("\nThat is not a choice.");
}
while(ch!='a' && ch!='b');
if(ch=='a')
{
printf("\n\nPlease enter the name of the file to save to --> ");
fflush(stdin);
scanf("%s",oname);
if((ofile=fopen(oname,"w"))!=NULL)
{
while((c=getc(file)) !=EOF);
fprintf(ofile, "%c", crypt(c, 'd', cd));
printf("File %s decrypted and saved as %s\n",iname,oname);
}
else printf("\n\nThe file %s cannot be written to.\n", oname);
}
else {
printf("\n");
while((c=getc(file)) !=EOF)
{
ch=crypt(c,'d',cd);
if(ch!=7) /* 7 is the bell - really annoying */
printf("%c", ch);
}
printf("\n\n");
}
}
else printf("\n\nThe file %s cannot be found.\n", iname);
}
else if(choice=='c')
ret= 0;
if(ret==1)
{
printf("(Press any key to continue)");
getch();
}
return ret;
}
unsigned int code(void)
{
char password[4];
char * pntr;
unsigned int pnumber;
int c;
do
{
printf("\nPlease enter the password (three letters, lower case) -->");
for(c=0;c<3;c++)
{
password[c]=getch();
printf("*");
}
if( password[0] < 97 || password[0] > 122 || password[1] < 97
|| password[1] > 122 || password[2] < 97 || password[2] > 122)
printf("\n\nThat password is not all lower case letters.");
}
while( password[0] < 97 || password[0] > 122 || password[1] < 97
|| password[1] > 122 || password[2] < 97 || password[2] > 122);
pntr=password; /* my formula is not bombproof - there some different passwords that will return the same value */
pnumber= (*pntr-96);
pntr++;
pnumber+= 2* (*pntr-96);
pntr++;
pnumber+= 3* (*pntr-96);
pnumber+=2;
return pnumber;
}
unsigned char crypt(unsigned char in, char mode, unsigned char codefactor)
{
int ch;
if(mode=='e')
{
ch=in-codefactor;
if(ch < 1)
ch=ch+255;
if( ch==26) /* eof character-don't want to put it to file */
ch=0;
}
else
{
if(ch==0) /* converts 0 back to eof */
ch=26;
ch=in+codefactor;
if(ch>255)
ch=ch-255;
}
return ch;
}
void aprint(char *what, int attr)
{
char *pntr;
int row, col;
pntr=what;
row=cursrow();
col=curscol();
while(*pntr!=0)
{
writechs(*pntr,attr,1);
pntr++;
poscurs(row, ++col);
}
}
void header(void)
{
int attr1;
int attr2;
int fg,bg;
if(MONOCHROME) /*detect card type */
{ /* monochrome */
attr1=0x07;
attr2=0x09;
}
else { /* color */
attr1= 0x17;
attr2= 0x1F;
fg=ANSI_FG_WHITE;
bg=ANSI_BG_BLUE;
}
if(isansi()==0)
clrscrn2(attr1);
else ansi_clrscrn2(fg, bg);
printf("\n\t\t");
aprint("NSCRYPT File encrypter / decrypter",attr2);
printf("\n\t\t");
aprint("Copyright 1996 by NebSoft Inc.", attr2);
printf("\n\t\t");
aprint("Written by Ben Fasenfest.", attr2);
printf("\n\n");
}
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