int character_value(char character)
{
const char alphabet[128] = {'@', '@', '$', '@', '@', '@', '@', '@', '@', '@', '\n', '@', '@',
'\r','@', '@','@', '_', '@', '@', '@', '@', '@','@', '@', '@', '@','@', '@', '@', '@',
'@',' ', '!', '"', '#', '@', '%', '&', '\'', '(', ')','*', '+', ',', '-', '.', '/',
'0', '1', '2', '3', '4', '5', '6', '7','8', '9', ':', ';', '<', '=', '>', '?', '@',
'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', '@', '@', '@','@', '@'};
int i;
for(i=0;i<128;i++){
if(character == alphabet[i]){
return i;
}
}
return -1; //no valid character
}
int bin2int(char * binary)
{
int i;
int sum = 0;
int length;
length = strlen(binary);
for(i=0;i<length;i++){
if(binary[i] == '1'){
//sum += (int)pow((double)2,(double)(length-1-i));
sum += 0x01<<(length-1-i);
}
}
return sum;
}
void process_message(char * message_str, char * message)
{
char buffer[8]="\0";
int length;
int i;
int character = -1;
char base[8]="\0";
char carry[8]="\0";
char rdbuffer[8]="\0";
//init
message_str[0] = '\0';
length = strlen(message);
if(length<=15){
strcat(message_str, "00000");
} else {
if(length>160){
length = 160;
}
strcat(message_str, "0000");
}
itoa(length, buffer, 16); //convert integer to hex string
strcat(message_str, buffer);
for(i=0;i<=length;i++){
if(i == length){
if(base[0] != '\0'){
character = bin2int(base);
itoa(character, base, 16);
if(strlen(base)==1){
base[1]=base[0];
base[0]='0';
base[2]='\0';
}
strcat(message_str, base);
}
break;
}
character = character_value(message[i]);
if(character != -1){
strcpy(buffer,"0000000");
itoa(character, rdbuffer, 2);
strcpy(buffer+7-strlen(rdbuffer), rdbuffer);
if(i != 0 && i%8 !=0){
strncpy(carry, buffer+7-i%8, i%8);
carry[i%8] = '\0';
strcat(carry, base);
character = bin2int(carry);
itoa(character, carry, 16);
if(strlen(carry)==1){
carry[1]=carry[0];
carry[0]='0';
carry[2]='\0';
}
strcat(message_str, carry);
strncpy(base, buffer, 7-i%8);
base[7-i%8] = '\0';
} else{
strcpy(base, buffer);
}
} else{
//ERROR: Not a valid character
}
}
}