Implementing-cryptography-using-python

xiv
Contents
Pseudorandomness115
Breaking C’s rand() Function 116
Solving Systems of Linear Equations 117
Frequency Analysis 120
Cryptanalysis with Python 123
Using an Online Word List 125
Determining the Frequency 126
Breaking the Vigenère Cipher 129
Summary138
Chapter 5 Stream Ciphers and Block Ciphers 139
Convert between Hexdigest and Plaintext 140
Use Stream Ciphers 141
ARC4147
Vernam Cipher 148
Salsa20 Cipher 149
ChaCha Cipher 151
Use Block Ciphers 156
Block Modes of Operations 158
ECB Mode 158
CBC Mode 159
CFB Mode 160
OFB Mode 162
CTR Mode 163
Tricks with Stream Modes 164
DIY Block Cipher Using Feistel Networks 165
Advanced Encryption Standard (AES) 167
Using AES with Python 167
File Encryption Using AES 169
File Decryption Using AES 169
Summary169
Chapter 6 Using Cryptography with Images 171
Simple Image Cryptography 171
Images and Cryptography Libraries 174
Understanding the Cryptography Library 174
Understanding the Cryptosteganography Library 175
Image Cryptography 175
File Cryptography Using Fernet 176
Image Cryptography Using Fernet 179
AES and Block Modes of Operations 180
Exploring a Simple ECB Mode Example 181
Exploring a Simple CBC Mode Example 185
Applying the Examples 186
Steganography187
Storing a Message Inside an Image 188