Tested File Reads as expected but on Complete Code Not Working

Question

I have tested the following code to read the tester.txt file and it outputted my expectation, however, when I inserted similar code in my complete code, it just stuck at: "Data from the file:" Why it is not outputting my expectation?

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

char c[1000];
FILE *fptr;

int fileReader(){
    if ((fptr = fopen("tester.txt", "r")) == NULL) {
        printf("Error! File cannot be opened.");
        // Program exits if the file pointer returns NULL.
        exit(1);
    }
    // reads text until newline is encountered
    fscanf(fptr, "%[^\n]", c);
    fclose(fptr);
}
int main() {

    fileReader();
    printf("Data from the file:\n%s", c);
    char* anotherone = (char*) c; 
    printf(anotherone);

    return 0;
}

Another code to read file:

int fileReader() {

   fp = fopen("tester.txt", "r");
   fscanf(fp, "%s", c);
   fclose(fp);

}

The complete code is:

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

int success = 0;

void handleOpenSSLErrors(void)
{
    ERR_print_errors_fp(stderr);
    abort();
}

unsigned char* decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *key, unsigned char *iv ){

    EVP_CIPHER_CTX *ctx;
    unsigned char *plaintexts;
    int len;
    int plaintext_len;
    
    unsigned char* plaintext = malloc(ciphertext_len);
    bzero(plaintext,ciphertext_len);

  
    if(!(ctx = EVP_CIPHER_CTX_new())) handleOpenSSLErrors();

    
    if(1 != EVP_DecryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, key, iv))
        handleOpenSSLErrors();

  
    EVP_CIPHER_CTX_set_key_length(ctx, EVP_MAX_KEY_LENGTH);

    if(1 != EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
        handleOpenSSLErrors();
   
    plaintext_len = len;
    
    // return 1 if decryption successful, otherwise 0
    if(1 == EVP_DecryptFinal_ex(ctx, plaintext + len, &len)) 
        success = 1;
    plaintext_len += len;

   
    /* Add the null terminator */
    plaintext[plaintext_len] = 0;

    /* Clean up */
    EVP_CIPHER_CTX_free(ctx);
    //delete [] plaintext;
    return plaintext;
}


size_t calcDecodeLength(char* b64input) {
    size_t len = strlen(b64input), padding = 0;

    if (b64input[len-1] == '=' && b64input[len-2] == '=') //last two chars are =
        padding = 2;
    else if (b64input[len-1] == '=') //last char is =
        padding = 1;
    return (len*3)/4 - padding;
}

void Base64Decode( char* b64message, unsigned char** buffer, size_t* length) {

    
    BIO *bio, *b64;  // A BIO is an I/O strean abstraction

    int decodeLen = calcDecodeLength(b64message);
    *buffer = (unsigned char*)malloc(decodeLen + 1);
    (*buffer)[decodeLen] = '\0';

    bio = BIO_new_mem_buf(b64message, -1);
    b64 = BIO_new(BIO_f_base64());
    bio = BIO_push(b64, bio);

    //BIO_set_flags(bio, BIO_FLAGS_BASE64_NO_NL); //Do not use newlines to flush buffer
    *length = BIO_read(bio, *buffer, strlen(b64message));
    BIO_free_all(bio);
}

void initAES(const unsigned char *pass, unsigned char* salt, unsigned char* key, unsigned char* iv )
{
    //initialisatio of key and iv with 0
    bzero(key,sizeof(key)); 
    bzero(iv,sizeof(iv));
  
    EVP_BytesToKey(EVP_aes_128_cbc(), EVP_sha1(), salt, pass, strlen(pass), 1, key, iv);
}


int checkPlaintext(char* plaintext, char* result){

    int length = 10; // we just check the first then characters
    return strncmp(plaintext, result, length);

}

char *cas[1000];
FILE *fptr;

int fileReader(){
    if ((fptr = fopen("tester.txt", "r")) == NULL) {
        printf("Error! File cannot be opened.");
        // Program exits if the file pointer returns NULL.
        exit(1);
    }
    // reads text until newline is encountered
    fscanf(fptr, "%[^\n]", cas);
    fclose(fptr);

}

int main (void)
{
    
    fileReader();
    printf("Data from the file:\n%s", cas);
    char* ciphertext_base64 = (char*) cas;   

    char* plaintext = "to be or not to be is the question";
    char dict[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
        
    int decryptedtext_len, ciphertext_len, dict_len;

    // cipher (binary) pointer and length
    size_t cipher_len; // size_t is sizeof(type)
    unsigned char* ciphertext;
  
    unsigned char salt[8];
    
    ERR_load_crypto_strings();
    
    Base64Decode(ciphertext_base64, &ciphertext, &cipher_len);

    unsigned char key[16];
    unsigned char iv[16];

    unsigned char plainpassword[] = "00000";
    unsigned char* password = &plainpassword[0];
    
    // retrive the slater from ciphertext (binary)
    if (strncmp((const char*)ciphertext,"Salted__",8) == 0) { // find the keyword "Salted__"
        
        memcpy(salt,&ciphertext[8],8);
        ciphertext += 16; 
        cipher_len -= 16;
    
    }

    dict_len = strlen(dict);
    
    time_t begin = time(NULL);


    for(int i=0; i<dict_len; i++)
        for(int j=0; j<dict_len; j++)
            for(int k=0; k<dict_len; k++)
                for(int l=0; l<dict_len; l++)
                    for(int m=0; m<dict_len; m++){
                        *password = dict[i];
                        *(password+1) = dict[j];
                        *(password+2) = dict[k];
                        *(password+3) = dict[l];
                        *(password+4) = dict[m];

                        
                        initAES(password, salt, key, iv);
                        unsigned char* result = decrypt(ciphertext, cipher_len, key, iv);
                        
                        if (success == 1){
                            if(checkPlaintext(plaintext, result)==0){
                                
                                printf("Password is %s\n", password);
                                
                                time_t end = time(NULL);
                                printf("Time elpased is %ld seconds", (end - begin));
 
                                return 0;
                            }

                        }
                       
                        free(result);
                        
                        
                    }

            
    // Clean up
    
    EVP_cleanup();
    ERR_free_strings();


    return 0;
}

Answer 1

1. char *cas[1000]; should be char cas[1000];, I would say this is the main issue, you are using an array of pointers as if it was a character array, this is very likely what's causing your program to fail.

---

2. Fix bzero, pass the size of the array as argument. When you use sizeof(key) in initAES(), what you are actually getting is the size of the pointer, not the size of the container it points to. More oh this in How to find the 'sizeof' (a pointer pointing to an array)?

You can add size of the array as a global constant with a macro:

#define SIZE 16 // size of the arrays

//...

void initAES(const unsigned char *pass, unsigned char* salt, unsigned char* key, unsigned char* iv )
{
    //initialisatio of key and iv with 0
    bzero(key, SIZE); 
    bzero(iv, SIZE);
  
    EVP_BytesToKey(EVP_aes_128_cbc(), EVP_sha1(), salt, pass, strlen(pass), 1, key, iv);
}

You can use it to define the size in main making your code more consistent.

int main (void)
{
    //...
    unsigned char key[SIZE];
    unsigned char iv[SIZE];
    //...
}

---

3. For good measure make fileReader have void return type if you don't want it to return an int.

I always advise the use of compiler warnings at full blast and preferably to treat warnings as errors.