Implementing-cryptography-using-python

Chapter 6 ■ Using Cryptography with Images 197
blue = fits.PrimaryHDU(data=b_data)
blue.header["AUTHOR"] = author
blue.header["LATOBS"] = location_lat
blue.header["LONGOBS"] = location_long
blue.header["SATNAME"] = satellite
blue.writeto('chapter6/fits/blue.fits', overwrite=True)
The output of the previous code takes our secret image from the beginning
of the chapter and creates three unique FITS files using red, green, and blue
channels. You will see in Figure 6.15 that the header for green.fits contains our
secret information. As you might expect, we could easily encrypt the image too.
Figure 6.15: FITS Files
Summary
In this chapter, you were introduced to a couple of libraries that perform cryptographic
and steganography tasks on images. It is important for you to understand
how various AES block modes work and how they apply to image files.
We concluded the chapter by using the CryptoSteganography library to hide
various types of files. Hiding messages inside an image could affect the properties
of the image. This was obvious when we hid a 30-second MP3 file inside
an image. The decryption process for each of these examples is dependent on
the use of a secret key; if the recipient of the file does not have the secret key,
your message will remain a secret even if the recipient can see that the visual
properties of the file have changed. Finally, we explored the FITS file format.
While the FITS format may not provide much value on the surface, the amount
of data that can be stored and encrypted is incredible.