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Full Discussion: compile a c program in a encrypted way
Top Forums UNIX for Advanced & Expert Users compile a c program in a encrypted way Post 302474632 by jim mcnamara on Wednesday 24th of November 2010 10:25:41 PM
Old 11-24-2010
Here is one explicitly defined way to do it.
1. create a file with 600 permissions just for the user, in a directory with 700 permissions.
We'll call the file .data

2. use crpyt (comes with most unixes)
Code:
# From your command line:  get a password with mixed characters then
# also create another password - this is a problem as well - the key for the password file
echo 'password' > clear.file

crypt key< clear.file >  .data
rm clear.file

3. Now we have the key (another password to mess with)
Code:
# at the command line
key=keypassword
echo "$key" > .keepme
chmod 700 .keepme

4. In your C code
Code:
FILE *fp=fopen( "/path/to/.keepme", "r");
FILE *cmd=NULL;
char tmp[32]={0x0};
char *p=NULL;
char cmdstring[128]={0x0};

fgets(tmp, sizeof(tmp), fp);
fclose(fp);
p=strchr(tmp, '\n');
if(p!=NULL) 
   *p=0x0;  /* lose the newline */
sprintf( cmdstring, "crypt %s < .data | pr", tmp);
cmd=popen(cmd, "r");
fgets(cmd, sizeof(tmp), cmd);
pclose(cmd);
# use pwd  to connect.
sprintf( myconnectstring, 
      "db2 connect to DBNAME user USERNAME using %s;", tmp);

This means that only root or the special user you have for the job can see the files. Be sure permissions are set correctly on your executable.

It is not hacker-proof by any means, but casual users will not be able to do much with. Be sure your .keepme and .data files are set correctly permissions-wise. There is no error checking in the code, it needs some.
 

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LEARN ABOUT DEBIAN

ijs-config

IJS-CONFIG(1)						      General Commands Manual						     IJS-CONFIG(1)

NAME

       ijs-config - script to get information about the installed version of ijs

SYNOPSIS

       ijs-config [--prefix[=DIR]] [--exec-prefix[=DIR]] [--version] [--libs] [--cflags]

DESCRIPTION

       ijs-config  is  a program that is used to determine the compiler and linker flags that should be used to compile and link programs that use
       IJS.

OPTIONS

       This program follows the usual GNU command line syntax, with long options starting with two dashes (`-').  A summary of options is included
       below.

       --help Show summary of options.	This may list additional advanced package configuration options not detailed in this manual page.

       --version
	      Show installed libijs version.

       --libs Print the linker flags that are necessary to link an IJS program.

       --cflags
	      Print the compiler flags that are necessary to compile an IJS program.

       --prefix=PREFIX
	      If  specified,  use PREFIX instead of the installation prefix that IJS was built with when computing the output for the --cflags and
	      --libs options. This option is also used for the exec prefix if --exec-prefix was not  specified.  This  option  must  be  specified
	      before any --libs or --cflags options.

       --exec-prefix=PREFIX
	      If  specified, use PREFIX instead of the installation exec prefix that IJS was built with when computing the output for the --cflags
	      and --libs options.  This option must be specified before any --libs or --cflags options.

SEE ALSO

       gtk-config(1)

AUTHOR

       This manual page was written by Roger Leigh <rleigh@debian.org>, originally for the Debian GNU/Linux system.

								    5 Feb, 2004 						     IJS-CONFIG(1)
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