utils.py

from PIL import Image

def encrypt(text, secret_key, img):
    image = Image.fromarray(img)
    pixels = list(image.getdata())
    binary_text = ''
    for char in text:
        binary_text+=format(ord(char), '08b')
    binary_secret = ''
    for char in secret_key:
        binary_secret+=format(ord(char), '08b')
    # print(binary_text)
    binary_text = binary_demorf(binary_text, binary_secret)
    binary_text = binary_text + binary_secret
    # print(binary_text)
    i = 0
    print("number of bits we can store (binary_text + binary_secret): ",3*len(pixels))
    new_pixels = []
    for rgb in pixels:
        tcr = []
        for clr in rgb:
            if i < len(binary_text):
                if binary_text[i] == '0':
                    if clr % 2 != 0:
                        clr -= 1
                else:
                    if clr % 2 == 0:
                        clr += 1
                i += 1
            tcr += [clr]
        new_pixels += [tuple(tcr)]
    new_image = Image.new(image.mode, image.size)
    new_image.putdata(new_pixels)
    return new_image

def decrypt(secret_key, img):
    image = Image.fromarray(img)
    pixels = list(image.getdata())
    binary_secret = ""
    for(char) in secret_key:
        binary_secret += format(ord(char), '08b')
    binary_text = ""
    for rgb in pixels:
        for(clr) in rgb:
            if clr % 2 == 0:
                binary_text += '0'
            else:
                binary_text += '1'
    
    # print(binary_secret)
    text_pos = binary_text.split(binary_secret)
    if len(text_pos) == 1:
        return "No text found"
    else :
        bt = text_pos[0];
        # print(bt)
        bt = binary_morf(bt, binary_secret)
        # print(bt)
        text = ""
        for i in range(0, len(bt), 8):
            text += chr(int(bt[i:i+8], 2))
        return text
    
def binary_demorf(binary_text,binary_secret):
    if len(binary_text) < len(binary_secret):
        return binary_text
    text = ""
    cidx =0
    idx = 0
    while idx < len(binary_text):
        ch = binary_text[idx]
        if cidx < len(binary_secret):
            if binary_secret[cidx] == ch:
                if cidx == len(binary_secret)-1:
                    cidx = 0
                    if ch == '0':
                        text += '1'
                    else:
                        text += '0'
                else:
                    text += ch
                    cidx += 1
                idx += 1
            else:
                if(binary_secret[0]==ch):
                    cidx=1
                else:
                    cidx=0
                text += ch
                idx+=1
        else:
            text += ch
            idx+=1
    return text

def binary_morf(binary_text,binary_secret):
    if len(binary_text) < len(binary_secret):
        return binary_text
    t = binary_secret[:-1] # secret without the last digit
    l = binary_text.split(t) # split text with that
    # print(l)
    result = ''
    i = 0;
    while i < len(l):
        cr = ""
        if(i!=0):
            cr = l[i][1:]
        else:
            cr = l[i]
        if i != len(l)-1:
            result += cr + binary_secret;
        else:
            result += cr
        i+=1
    return result