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Modern
Cryptography for
Cybersecurity
Professionals
Learn how you can leverage encryption to better
secure your organization's data
Lisa Bock
BIRMINGHAM—MUMBAI
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Modern Cryptography for Cybersecurity
Professionals
Copyright © 2021 Packt Publishing
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First published: May 2021
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No one really knows how planes stay in the air. They do, however, know that
lift, an aerodynamic force, allows them to take flight. I dedicate this book to
all those that believed in me, had faith in my abilities, and gave me the lift
to take off and excel in my field.
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Contributors
About the author
Lisa Bock is an experienced author with a demonstrated history of working in the
e-learning industry. She is a security ambassador with a broad range of IT skills and
knowledge, including on Cisco Security, CyberOps, Wireshark, biometrics, ethical
hacking, and IoT. Lisa is an author for LinkedIn Learning and an award-winning
speaker who has presented at several national conferences. She holds an MS in computer
information systems/information assurance from UMGC. Lisa was an associate professor
in the IT department at Pennsylvania College of Technology (Williamsport, PA) from
2003 until her retirement in 2020. She is involved with various volunteer activities, and
she and her husband Mike enjoy bike riding, watching movies, and traveling.
I'd like to thank Dr. Jacob Miller, long-time colleague at Pennsylvania
College of Technology, who had the foresight to create an Information
Assurance degree in 2003. His early effort exposed me to a field I genuinely
love. In addition, I'd like to thank Anita Wood for her continued wisdom,
advice, and ability to solve problems. Finally, I'd like to acknowledge the
entire Packt editing team, who have helped me to become a better author,
along with Product Manager Rahul Nair, with whom I have enjoyed
collaborating over the years.
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About the reviewer
Vipin Singh Sehrawat received his Ph.D. degree in computer science from The University
of Texas at Dallas, USA, in 2019. He is currently working as Lead Cryptographer in the
Data Security team of Seagate Research Group at Seagate Technology, Singapore. His
research interests include cryptography, combinatorics, extremal set theory, information
theory, number theory, software security, and network security.
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Table of Contents
Preface
Section 1:
Securing Our Data
1
Protecting Data in Motion or at Rest
Outlining the current threat Getting to know Bob and Alice 16
landscape 4
Outlining substitution and
Digitally transforming our world 4
transposition 16
Threatening the security of our data 6
Substituting characters 17
Understanding security services 8 Transposing the text 18
Investigating X.800 8 Breaking the code 19
Introducing common Summary 20
cryptographic concepts 12 Questions 20
Trusting a TTP 13 Further reading 22
Managing keys using the PKI 14
2
The Evolution of Ciphers
Early uses of cryptography 24 Encoding transmissions during
war 30
Using tattoos and scytales 24
Evaluating monoalphabetic ciphers 26 Communicating during wartime 30
Recognizing polyalphabetic ciphers 27 Examining the Enigma machine 33
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ii Table of Contents
Entering the digital age 34 Summary 39
Innovating in the field of computing 34 Questions 40
Developing the early ciphers 38 Further reading 41
3
Evaluating Network Attacks
Comparing passive and active Maintaining integrity 57
attacks 44
Protecting assets 57
Carrying out a passive attack 44 Managing risk 58
Launching an active attack 49
Summary 59
Protecting sensitive data 51 Questions 60
Understanding attack vectors 51 Further reading 62
Providing defense mechanisms 53
Section 2:
Understanding Cryptographic Techniques
4
Introducing Symmetric Encryption
Discovering the evolution of Dissecting block and stream
symmetric encryption 66 ciphers 83
Protecting customer data 67 Using a block cipher 83
Developing the Feistel cipher 67 Generating a stream 84
Creating the Lucifer cipher 71
Comparing symmetric
Outlining symmetric algorithms 72 encryption operation modes 84
Understanding symmetric encryption 72 Using ECB 85
Describing the Data Encryption Standard 74 Adding feedback 85
Illustrating the Advanced Encryption Applying CTR mode 87
Standard 76
Securing wireless
Identifying other symmetric algorithms 81
communications 88
Scheduling the keys 82
Preventing eavesdropping 89
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Table of Contents iii
Comparing protocols 89 Questions 92
Further reading 94
Summary 91
5
Dissecting Asymmetric Encryption
Realizing the need for Outlining RSA 106
asymmetric encryption 96 Visualizing an elliptical curve 108
Securely exchanging a key 97 Providing PGP 111
Outlining the PKCS 101 Trusting public keys 113
Understanding cryptographic Working with digital signatures 114
requirements 102 Providing core security services 114
Designing a strong algorithm 102 Creating a digital signature 116
Generating a key pair 103
Summary 117
Managing keys 104
Questions 118
Using asymmetric encryption 105
Further reading 119
Comparing public-key
algorithms 106
6
Examining Hash Algorithms
Describing a hash algorithm 122 Using the message digest algorithm 133
Creating a hash 122 Exploring the Secure Hash Algorithm
(SHA) 133
Employing a hash function 125
Recognizing other hash algorithms 134
Identifying optimal hash
Authenticating a message 135
properties 130
Creating a MAC 135
Generating a one-way function 130
Encrypting and authenticating data 137
Producing a fixed-size output 131
Consistently creating the same hash 131
Summary 138
Ensuring collision resistance 132
Questions 139
Comparing common hash Further reading 141
algorithms 132
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