Implementing-cryptography-using-python

190 Chapter 6 ■ Using Cryptography with Images
We now examine how the module works when you do not supply the
correct key. Change the key to anything else and then pass the new key into
the CryptoSteganography class:
>>> key = "AnotherKey"
>>> crypto_steganography = CryptoSteganography(key)
You can now use the retrieve() method to attempt to extract the message.
This time, when you print the retrieved value, you will get the value None,
indicating that the key is incorrect:
>>> secret = crypto_steganography.retrieve(modfile)
>>> print(secret)
None
Now that you have seen the components, let's put them all together and show
how hiding information using steganography changes the original file:
from cryptosteganography import CryptoSteganography
key = "1111222233334444!"
crypto_steganography = CryptoSteganography(key)
print()
print('The program is looking for an image named ch6_secret_image.png\n')
origfile = "chapter6\steg\ch6_secret_image.png"
print('The image with the hidden message will be called steg_ch6_secret_
image.png\n')
modfile = "chapter6\steg\steg_ch6_secret_image.png"
secretMsg = ""
message1 = "Sympathy for the favorite nation, facilitating the illusion
of an imaginary common "
message2 = "interest in cases where no real common interest exists, and
infusing into one the "
message3 = "enmities of the other, betrays the former into a
participation in the quarrels and "
message4 = "wars of the latter without adequate inducement or
justification."
secretMsg = secretMsg.join([message1, message2, message3, message4])
crypto_steganography.hide(origfile, modfile, secretMsg)
secret = crypto_steganography.retrieve(modfile)
print("The secret that is hidden in the file is:\n")
print(secret)
print()