I'm writing a program that implements the Boneh-Franklin Identity Based Encryption. For the actual encryption methods, I use Blowfish which I got from (https://voltar.org/). I'm trying to adapt the blowfish encryption/decryption code to my program. The difference in my program is that I read the message from the standard input, encrypt it and print the encryption, then decrypt it and print the decryption (which should be the original message). Currently, I read the input message up to a "?" character and then try to follow the code from the site. However, the decryption is printed as unreadable characters. I tried to solve this problem but I got stuck. Can you please help me?
//initializations
BF_KEY s_key; //shared key of the blowfish encryption
char plain[1000000]; //the plaintext of the message
char cipher[1000000]; //the ciphertext of the message
char byte; //to hold the byte of the msg
char *token; //points to tokens of the msg
char IV[8]="MY*IV000"; //the initialization vector
int offset = 0; //the offset of encryption
int b_count = 0; //number of bytes in d_buf
char block[8]; //blocks of encryption
char msg[1000000]; //the input msg from the user
int j; //used to read input in a loop with getchar
int i; //for-loop value
int len; //used to calculate lengths different variables
int f; //flag for the setup stage
int q; //used to read input in a loop with getchar
q=0; //reset the index reader
char in; //to read characters
printf("Please enter the message you wish to send:\n");
************ This is my code to read the input message: ***************
//this loop reads the input from the user since C does not
//provide a safe function to read strings with white spaces
while (in != '?'){
in=getchar();
if(in != '?') //dont include the delim character in the string
msg[q++]=in;
}
msg[q]='\0'; //truncate the string by the null character
************ Then I used the code (cited and referenced) for encryption ***************
Of course I modified it as message read from stdin not program args
for(i=0; i<strlen(msg); i++) //copy the input message to plain
plain[i] = msg[i];
//set up the shared key of the BF encryption
BF_set_key(&s_key, strlen(ekey_buf), ekey_buf);
while(1){
for(i=0; i<8; i++) //reinitiate the block of 8 characters each time
block[i] = 0;
strncpy(block, plain+offset, 8);
BF_cbc_encrypt(plain+offset, cipher, 8, &s_key, IV, BF_ENCRYPT);
for(i=0; i<strlen(cipher); i++){
printf("%02x", (unsigned char) cipher[i]);
}
if( strlen(plain+offset)>8 ){ //if there is still more characters
offset += 8; //process the next block of 8 characters
} else
break;
}
//the cipher is correctly printed
************ Then I used the code (cited and referenced) for decryption ***************
Here, I excluded the part where it tokenized the cipher and created the plain char array for decryption, I simply passed the cipher array to be decrypted (as it is output from the encryption function), and stored in the plain char array with length = strlen(cipher)
//set up the shared key of the BF encryption
BF_set_key(&s_key, strlen(dkey_buf), dkey_buf);
BF_cbc_encrypt(cipher, plain, strlen(cipher), &s_key, IV, BF_DECRYPT);
printf("plain after decryption: %s\n", plain);
//HERE IS THE PROBLEM: I get unreadable characters as output of this line
Any help is appreciated. Sorry for the inconvenience and many thanks in advance.