Implementing-cryptography-using-python

174 Chapter 6 ■ Using Cryptography with Images
Figure 6.3: Side by side of ch6_secret_image.jpg and d_ch6_secret_image.jpg
Images and Cryptography Libraries
Let’s change our focus to implementing libraries that will make our cryptography
lives a little easier. We will revisit the Cryptography library that we introduced
in Chapter 1, and we will introduce the Cryptosteganography library that will
give us the ability to explore steganography using Python later in this chapter.
Understanding the Cryptography Library
Cryptography is the name of a Python package that provides cryptographic
primitives and recipes. The library boasts to be your “cryptographic standard
library,” and it currently supports various versions in Python. To install the
library, perform a pip install cryptography.
The Cryptography library includes both high-level recipes and low-level
interfaces to common cryptographic algorithms such as symmetric ciphers,
message digests, and key derivation functions. The Fernet example shown next
highlights an example of a high-level interface. Check out the following quick
sample code to ensure that you have the Cryptography library installed:
from cryptography.fernet import Fernet
key = Fernet.generate_key()
f = Fernet(key)
print ("The key is %s", f)
print ()
ciphertext = f.encrypt(b"This is a secret message.")
print (ciphertext)
print ()