How to use an array that stores one byte in the fread function(In Triple_DES Algorithm)

Question

I am trying to use the fread function. In the code below, input_text stores values ​​in bit units, but file_size represents the number of bytes. Because of this, wrong values ​​are entered in the input_text array, and I am curious about how to solve this.

'''
fseek(Ptr_input, 0, SEEK_END);  
file_size = ftell(Ptr_input);   
fseek(Ptr_input, 0, SEEK_SET); 

char* input_text = (char*)malloc((file_size) * 8 + 64);
if (input_text == NULL) {
    printf("malloc failed.\n");
    fclose(Ptr_input);
    exit(1);
}

fread(input_text, 1, file_size, Ptr_input);`
'''

To sum up, what I want to do is to solve an error when trying to save values ​​in the input_text array that stores values ​​in bit units in the fread function, which processes values ​​in byte units.