Advance Encryption Standard, Basic Encryption Standard

1. Advanced
Encryption Standard
(AES)
Securing the Digital World
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2. Agenda
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• Introduction to AES
• History and Development
• How AES Works
• Strengths and Advantages
• Practical Applications

3. Introduction
to AES
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Introduction to Cryptography

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Definition of
AES
AES, or the Advanced Encryption
Standard, is a widely-used symmetric
encryption algorithm that plays a
crucial role in securing digital data. It
was established as a federal standard
for encryption by the U.S. National
Institute of Standards and Technology
(NIST) in 2001. AES has since become a
global encryption standard used to
protect sensitive information in various
applications, including secure
communication, data storage, and
more.

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Encryption
What is Encryption Goal of Encryption
• Encryption is the process of converting
data or information into a secure and
unreadable format, known as cipher text,
to protect it from unauthorized access or
interception. This transformation is done
using an encryption algorithm and a
secret encryption key.
• encryption is a fundamental tool for
safeguarding digital information, providing
a strong defense against unauthorized
access and ensuring the privacy and
security of data in a variety of applications.

6. Examples of Encryption Algorithm
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• Symmetric Encryption – AES, DES
• Asymmetric Encryption (Public Key Encryption) – RSA, ECC
• Hash Functions – SHA-256, MD5
• Message Digest (One-Way) Encryption – bcrypt, PBKDF2
• End-to-End Encryption (E2E)
• File and Disk Encryption – BitLocker, File Vault, LUKS
• Network Encryption (TLS/SSL)
• Database Encryption
• Homomorphic Encryption
• Quantum Encryption - QKD
• Transparent Data Encryption (TDE)

7. History and
Development
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Background of
AES
1970 DES used a fixed 56-bit key length, which
was considered secure at the time but
became increasingly vulnerable to brute-
force attacks as computing power advanced.
Data Encryption Standard (DES)
NIST announced a competition, known as the
Advanced Encryption Standard (AES) competition, in
1997, inviting the global cryptographic community
to submit encryption algorithms for evaluation.
Initiation of AES Development
Rijndael was selected because it had the
best combination of security, performance,
efficiency, implementability and flexibility
Selection of
Rijndael
AES was officially adopted as a federal
standard for encryption by the U.S.
government in 2001 through Federal
Information Processing Standard (FIPS) 197.
Adoption and Global Usage
1997
2000
2001

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AES VS DES
AES DES
• Uses symmetric-key encryption algorithms
• Varieties of Key length – 128, 192, and 256 bits
• Considered highly secure
• Employs a complex algorithm that includes
substitution, permutation, and mixing operations in
multiple rounds
• Uses symmetric-key encryption algorithms
• Fix key length – 56 bits
• Vulnerable to brute-force attacks
• Simplicity of the algorithm contributed to its
vulnerability over time.

10. How AES
Works
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11. How AES works
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• Key Generation: AES requires a secret key for encryption and decryption. The key must be a specific length
(128, 192, or 256 bits) depending on the chosen AES variant. Key generation is a crucial step, and the security of
AES relies heavily on the strength of the secret key.
• Data Division: The plaintext data to be encrypted is divided into fixed-size blocks. In AES, each block is 128 bits
(16 bytes).
• Initial Round: AES operates on each block through a series of rounds. In the initial round, the plaintext block is
combined with the initial secret key.
• Rounds: The number of rounds in AES depends on the key length:
• 128-bit key: 10 rounds
• 192-bit key: 12 rounds
• 256-bit key: 14 rounds
• In each round, a combination of substitution, permutation, and mixing operations is applied to the data using a
round key derived from the original secret key.
• Final Round: The final round is similar to the other rounds but lacks the "MixColumns" step, which is present in
all previous rounds.
• Output: After all the rounds are completed, you have the ciphertext, which is the encrypted data.
• Decryption: To decrypt the ciphertext, the same AES algorithm is applied but in reverse, using the same secret
key (or a derived key) and reversing the order of the round keys.

12. The AES Cipher
• Block length is limited to 128 bit
• The key size can be independently specified to 128, 192 or 256 bits
Key size (words/bytes/bits) 4/16/128 6/24/192 8/32/256
Number of rounds 10 12 14
Expanded key size (words/byte) 44/176 52/208 60/240
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13. The AES Cipher
• Key received as input array of 4 rows and Nk columns
• Nk = 4,6, or 8, parameter which depends key size
• Input key is expanded into an array of 44/52/60 words of
32 bits each
• 4 different words serve as a key for each round
k0 k4 k8 k12
k1
k2
k3
k5
k6
k7
k9
k10
k11
k13
k14
k15
w0 w1 w2 …… w42 w43
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14. The AES Cipher
• Single 128 bit block as input
• Copied to a State array with Nb columns (Nb=4)
in0 in4 in8 in12
in1
in2
in3
in5
in6
in7
in9
in10
in11
in13
in14
in15
S00 S01 S02 S03
S10
S20
S30
S11
S21
S31
S12
S22
S32
S13
S23
S33
o0 o4 o8 o12
o1
o2
o3
o5
o6
o7
o9
o10
o11
o13
o14
o15
Input State array Output
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15. The AES Cipher
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• Number of rounds, Nr, depends on key size
• Each round is a repetition of functions that perform a
transformation over State array
• Consists of 4 main functions: one permutation and three
substitutions
Substitute bytes, Shift rows, Mix columns, Add round key

16. The AES Cipher
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• AddRoundKey() – round key is added to the State using XOR
operation
• MixColumns() – takes all the columns of the State and mixes their
data, independently of one another, making use of arithmetic over
GF(2^8)
• ShiftRows() – processes the State by cyclically shifting the last three
rows of the State by different offsets
• SubBytes() – uses S-box to perform a byte-by-byte substitution of
State

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The AES Cipher
Add round key
Substitute bytes
Shift rows
Mix columns
Add Round key
Substitute bytes
Shift rows
Mix columns
Add round key
Substitute bytes
Shift rows
Add round key
plaintext
Cipher text
key
W[4,7] W[36,39] W[40,43]
Round
1
Round
9

18. EXAMPLE of CIPHER CODE
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19. The AES Cipher
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• Only Add round key makes use of the key
• Other three functions are used for diffusion and confusion
• Final round consists of only three stages

20. EXAMPLE OF INVERSE CIPHER CODE
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21. The AES Inverse Cipher
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• Decryption algorithm uses the expanded key in reverse order
• All functions are easily reversible and their inverse form is used in
decryption
• Decryption algorithm is not identical to the encryption algorithm
• Again, final round consists of only three stages

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The AES Inverse Cipher
Add round key
Inv. Shift rows
Inv. Sub bytes
Add round key
Inv. Mix Columns
Inv. Shift rows
Inv. Sub bytes
Add round key
Inv. Mix columns
Inv. Shift rows
Inv. Sub bytes
Add round key
ciphertext
plaintext
key
W[36,39] W[4,7] W[0,3]
Round
1
Round
9

23. Strengths
and
Advantages
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24. Strengths and Advantages
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• Security: AES is considered secure against all known practical attacks when
used with sufficiently long and random keys. Its strength lies in the
complexity of its operations, which includes substitution, permutation, and
key mixing, making it resistant to various cryptographic attacks like brute-
force, differential, and linear attacks.
• Key Length Options: AES supports key lengths of 128, 192, and 256 bits,
allowing users to choose the level of security they need. Longer keys provide
stronger encryption but may require more computational resources.
• Efficiency: AES is computationally efficient and can be implemented in both
software and hardware. It is optimized for modern computer architectures,
making it practical for a wide range of applications, including encryption of
data at rest and in transit.

25. Strengths and Advantages
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• Standardization: AES is a widely recognized and standardized encryption
algorithm, which enhances interoperability. It is used in various security
protocols and applications, including SSL/TLS for secure web communication
and file encryption tools.
• Resistance to Attacks: AES has been extensively analyzed and reviewed by
cryptographers worldwide. It has withstood years of scrutiny and has a strong
security track record. It is known to be resistant to known cryptographic
attacks, provided that the key is properly generated and managed.
• Mathematically Sound: AES's security is based on well-established
mathematical principles, which adds to its credibility and trustworthiness. It
relies on a strong combination of substitution (S-boxes), permutation (P-
boxes), and key mixing operations.

26. Strengths and Advantages
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• Flexibility: AES can be used in various modes of operation (e.g., ECB, CBC,
GCM) to suit different encryption requirements, such as confidentiality,
integrity, and authenticated encryption.
• Publicly Available: The AES algorithm is publicly available and free to use. This
transparency allows security experts to review and analyze its design, which
contributes to its overall security.
• Global Adoption: AES is used worldwide by governments, financial
institutions, businesses, and individuals for securing sensitive data. Its
widespread adoption has led to extensive testing and validation.
• Longevity: AES was selected as the encryption standard by the U.S. National
Institute of Standards and Technology (NIST) in 2001, and it has remained a
strong and trusted encryption choice for more than two decades.

27. Practical
Applications
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28. Practical Application
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• AES (Advanced Encryption Standard) is widely used in various practical applications to
secure data and communications. Here are some common practical applications for AES:
1. Data Encryption for File Storage
2. Secure Communication
3. Virtual Private Networks (VPNs)
4. Database Encryption
5. Secure Messaging Apps
6. Data Backup and Cloud Storage
7. Full Disk Encryption
8. Software and Application Security
9. Financial Transactions
10. IoT Security
11. Military and Government Communications
12. Secure Boot and Firmware Updates

29. Icebreaker
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Head, Shoulder, Knees, Toes, Slippers

30. Q&A
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31. Conclusion
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Recap of the Lesson

32. Conclusion
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• Encryption is a fundamental tool in information security, providing a robust
defense against unauthorized access and data breaches.
• We explored various types of encryption, from symmetric and asymmetric
encryption to hashing and end-to-end encryption.
• The choice of encryption method depends on factors like security requirements,
performance, and specific application needs.
• Leading encryption standards, such as AES and RSA, play a pivotal role in
securing digital data across the globe.
• Proper key management is crucial for the effective implementation of encryption
and safeguarding encrypted data.
• Encryption is a critical component of data protection, ensuring confidentiality,
integrity, and privacy in the digital age.

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Thank You

34. Quiz
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35. 1. What does AES stand for?
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A) Advanced Encryption System
B) Advanced Encryption Standard
C) Algorithm for Encryption and Security
D) Advanced Encoding System

36. 2. How many rounds of encryption does AES-128 have?
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A) 10 rounds
B) 12 rounds
C) 14 rounds
D) 16 rounds

37. 3. What is the key length of AES-192?
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A) 64 bits
B) 128 bits
C) 192 bits
D) 256 bits

38. 4. AES operates on blocks of how many bits at a time?
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A) 64 bits
B) 128 bits
C) 256 bits
D) 512 bits

39. 5. Which type of encryption does AES
use?
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A) Symmetric-key encryption
B) Asymmetric encryption
C) Hybrid encryption
D) None of the above

40. 6. Who developed the Rijndael algorithm, which
became AES?
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A) Alan Turing
B) Vincent Rijmen and Joan Daemen
C) Ron Rivest
D) Whitfield Diffie and Martin Hellman

41. 7. What is the maximum key length supported by AES?
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A) 64 bits
B) 128 bits
C) 192 bits
D) 256 bits

42. 8. What are the three standard key lengths for AES?
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A) 64, 128, 192 bits
B) 56, 128, 256 bits
C) 64, 256, 512 bits
D) 128, 192, 256 bits

43. 9. Which government agency initially selected AES as
the encryption standard in the United States?
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A) FBI (Federal Bureau of Investigation)
B) NSA (National Security Agency)
C) CIA (Central Intelligence Agency)
D) DEA (Drug Enforcement Administration)

44. 10. AES is considered secure against which type of
attack, which tries all possible keys?
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A) Birthday attack
B) Rainbow table attack
C) Brute-force attack
D) Man-in-the-middle attack