cotp.c

   1 /** Practical One-time Pad Library
   2  *
   3  * Created:20080514
   4  * By Jeff Connelly
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <getopt.h>
  11 #include <sysexits.h>
  12
  13 #include "libotp.h"
  14
  15 extern PAD *pads;
  16
  17 extern char *optarg;
  18 extern int optind;
  19
  20 void test()
  21 {
  22     char *o;
  23     unsigned int i;
  24
  25     load_config("otp.conf");
  26     show_pads();
  27
  28     /*
  29     printf("offset=%ld\n", read_offset(pads));
  30     write_offset(pads, 1213475);
  31     printf("offset=%ld\n", read_offset(pads));
  32     */
  33
  34     otp_decrypt("--EMOTP_BEGIN--1213434,\n"
  35             "gK1O22FPbxLmxrROfFHDCsM1LTsOAjjbRlHVM1p+WG+s6yslYVfzvtc=\n"
  36             "--EMOTP_END--\n", &o);
  37     puts(o);
  38     free(o);
  39
  40     otp_decrypt("--EMOTP_BEGIN--978,dc,\n"
  41             "hUZm1q0gX7pa6Alzbo9OZiT8wA==\n"
  42             "--EMOTP_END--\n", &o);
  43     puts(o);
  44     free(o);
  45
  46     o = otp_encrypt("hello world", strlen("hello world"), "dc", &i);
  47     printf("encrypt = %s\n", o);
  48     free(o);
  49
  50     otp_decrypt("junkasdsjdfldjf jdsfjunk--EMOTP_BEGIN--1213475,dc,\n"
  51             "v7jlXbCCvPv4S0k=\n"
  52             "--EMOTP_END--\n-tasjdktrailingjunkksjdjf", &o);
  53     puts(o);
  54     free(o);
  55
  56     free_pads();
  57 }
  58
  59 /* Operation mode - trinary :) */
  60 #define ENCRYPT -1
  61 #define AUTO     0
  62 #define DECRYPT 1
  63
  64 void usage()
  65 {
  66     fprintf(stderr, "usage: otp [-e | -d | ] [-t <pad_name>]\n"
  67             "\n"
  68             "Mode selection:\n"
  69             "-e     Encrypt\n"
  70             "-d     Decrypt with <pad_name>\n"
  71             "Default is automatic.\n"
  72             "\n"
  73             "-t     Specify pad name to encrypt with. Default: first pad.\n");
  74     exit(EX_USAGE);
  75 }
  76
  77 /* Read input data.
  78  *
  79  * @param size Set to number of bytes read.
  80  *
  81  * @return Input, caller frees.
  82  */
  83 char *read_input(unsigned int *size)
  84 {
  85     unsigned int i, buffer_size;
  86     char *input;
  87
  88     i = 0;
  89     buffer_size = 1024;
  90     input = malloc(buffer_size);
  91     if (!input) {
  92         perror("malloc input buffer");
  93         exit(EX_UNAVAILABLE);
  94     }
  95
  96     while(!feof(stdin)) {
  97         input[i++] = fgetc(stdin);
  98         if (input[i - 1] == EOF)
  99             break;
 100         if (i >= buffer_size) {
 101             buffer_size += 1024;
 102             input = realloc(input, buffer_size);
 103             if (!input) {
 104                 perror("realloc input buffer");
 105                 exit(EX_UNAVAILABLE);
 106             }
 107         }
 108     }
 109     input[i - 1] = 0;
 110     *size = i - 1;
 111
 112     return input;
 113 }
 114
 115 int main(int argc, char **argv)
 116 {
 117     int ch, mode;
 118     unsigned int length, output_length;
 119     char *to, *input, *output;
 120
 121     mode = AUTO;
 122     to = NULL;
 123
 124     while((ch = getopt(argc, argv, "edt:")) != -1) {
 125         switch(ch)
 126         {
 127         case 'e':
 128             mode = ENCRYPT;
 129             break;
 130         case 'd':
 131             mode = DECRYPT;
 132             break;
 133         case 't':
 134             to = optarg;
 135             break;
 136         case '?':
 137         default:
 138             usage();
 139         }
 140     }
 141     argc -= optind;
 142     argv += optind;
 143
 144     input = read_input(&length);
 145
 146     /* Automatic mode - guess based on magic markers.
 147      * Explicit modes still allowed so can encrypt data with
 148      * magic markers in it (if you ever want to). */
 149     if (mode == AUTO) {
 150         if (strstr(input, MARKER_BEGIN))
 151             mode = DECRYPT;
 152         else
 153             mode = ENCRYPT;
 154     }
 155
 156     load_config("otp.conf");
 157
 158     if (mode == ENCRYPT) {
 159         output = otp_encrypt(input, length, to, &output_length);
 160     } else if (mode == DECRYPT) {
 161         output_length = otp_decrypt(input, &output);
 162     }
 163
 164     printf("%s", output);
 165
 166     free(output);
 167     free_pads();
 168
 169     return 0;
 170 }
 171