#include <stdio.h>
#include <stdlib.h>
#include <string.h>

unsigned char *__base64_encode(const unsigned char *str, 
        int length, int *ret_length);
unsigned char *__base64_decode(const unsigned char *str, 
        int length, int *ret_length);

int main()
{
   unsigned char *str, *dst;
   char *source = "1";
   int  size;
 
   str = __base64_encode((unsigned char *)source, strlen(source), &size);
   printf("%s : %d\n", str, size);
   dst = __base64_decode(str, strlen((const char *)str), &size);
   printf("%s : %d\n", dst, size);
 
   free(str);
   free(dst);

   return 0;
 
}

static char __base64_table[] ={
   'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
   'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
   'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
   'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
   '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '\0'
};
 
static char __base64_pad = '=';
 
unsigned char *__base64_encode(const unsigned char *str, int length, int *ret_length) {
   const unsigned char *current = str;
   int i = 0;
   unsigned char *result = (unsigned char *)malloc(((length + 3 - length % 3) * 4 / 3 + 1) * sizeof(char));
 
   while (length > 2) { /* keep going until we have less than 24 bits */
      result[i++] = __base64_table[current[0] >> 2];
      result[i++] = __base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
      result[i++] = __base64_table[((current[1] & 0x0f) << 2) + (current[2] >> 6)];
      result[i++] = __base64_table[current[2] & 0x3f];
 
      current += 3;
      length -= 3; /* we just handle 3 octets of data */
   }
 
   /* now deal with the tail end of things */
   if (length != 0) {
      result[i++] = __base64_table[current[0] >> 2];
      if (length > 1) {
         result[i++] = __base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
         result[i++] = __base64_table[(current[1] & 0x0f) << 2];
         result[i++] = __base64_pad;
      }
      else {
         result[i++] = __base64_table[(current[0] & 0x03) << 4];
         result[i++] = __base64_pad;
         result[i++] = __base64_pad;
      }
   }
   if(ret_length) {
      *ret_length = i;
   }
   result[i] = '\0';
   return result;
}
 
/* as above, but backwards. :) */
unsigned char *__base64_decode(const unsigned char *str, int length, int *ret_length) {
   const unsigned char *current = str;
   int ch, i = 0, j = 0, k;
   /* this sucks for threaded environments */
   static short reverse_table[256];
   static int table_built;
   unsigned char *result;
 
   if (++table_built == 1) {
      char *chp;
      for(ch = 0; ch < 256; ch++) {
         chp = strchr(__base64_table, ch);
         if(chp) {
            reverse_table[ch] = chp - __base64_table;
         } else {
            reverse_table[ch] = -1;
         }
      }
   }
 
   result = (unsigned char *)malloc(length + 1);
   if (result == NULL) {
      return NULL;
   }
 
   /* run through the whole string, converting as we go */
   while ((ch = *current++) != '\0') {
      if (ch == __base64_pad) break;
 
      /* When Base64 gets POSTed, all pluses are interpreted as spaces.
         This line changes them back.  It's not exactly the Base64 spec,
         but it is completely compatible with it (the spec says that
         spaces are invalid).  This will also save many people considerable
         headache.  - Turadg Aleahmad <turadg@wise.berkeley.edu>
      */
 
      if (ch == ' ') ch = '+';
 
      ch = reverse_table[ch];
      if (ch < 0) continue;
 
      switch(i % 4) {
      case 0:
         result[j] = ch << 2;
         break;
      case 1:
         result[j++] |= ch >> 4;
         result[j] = (ch & 0x0f) << 4;
         break;
      case 2:
         result[j++] |= ch >>2;
         result[j] = (ch & 0x03) << 6;
         break;
      case 3:
         result[j++] |= ch;
         break;
      }
      i++;
   }
 
   k = j;
   /* mop things up if we ended on a boundary */
   if (ch == __base64_pad) {
      switch(i % 4) {
      case 0:
      case 1:
         free(result);
         return NULL;
      case 2:
         k++;
      case 3:
         result[k++] = 0;
      }
   }
   if(ret_length) {
      *ret_length = j;
   }
   result[k] = '\0';
   return result;
}