Confidentiality, Integrity, Availability, Non Repudiation, Authentication, Digital Signatures

1. Applied
Cryptography
by
Dr. J. Arul Valan
Assistant Professor
Department of Computer Science and Engineering
NIT Nagaland

2. Introduction
• Cryptography
• Crypto Secret
• Graphy Writing
• Secure Communication
Cryptography is the science of protecting information by transforming
it into a secure format (unreadable )

3. https://qph.fs.quoracdn.net/main-qimg-f1209976704e52635078e8e7a5f70c1f.webp

4. https://www.chinabrands.com/dropshipping/article-13-best-and-cheapest-online-shopping-sites-in-india-15714.html

5. Objectives / Goals / Functions - Cryptography
• Confidentiality (Privacy) - Ensuring that no one can read the message
except the intended receiver
• Integrity - Assuring the receiver that the received message has
not been altered in any way from the original.
• Availability - Assures that the system work promptly and service is
not denied to authorized users
• Non-Repudiation - A mechanism to prove that the sender really sent
this message
• Authentication - The process of proving one's identity
• Digital Signatures - Proving Source Identity

6. https://www.edureka.co/blog/what-is-cryptography/

7. Terminology
• Plain Text (PT) - Original Message
• Cipher Text (CT) - Scrambled or Coded message ( unreadable / Encrypted)
• Encryption (Enciphering) – Process of Converting PT into CT
• Decryption (Deciphering) - Process of Converting CT into PT
• Cipher (Cryptosystem)– Algorithm used in Enciphering & Deciphering
• Key - secret information used in Encryption & Decryption , known only
to the sender& receiver -

8. • Cryptanalysis - Transforming CT into PT message without knowledge
of the key - Code Breaking
• Cryptography – Encryption + Decryption
• Cryptology - Cryptography + Cryptanalysis

9. Model of Cryptosystem
C = Ek(P)
P = Dk(C)
https://www.tutorialspoint.com/cryptography/cryptosystems.htm

10. https://www.researchgate.net/figure/Classification-of-cryptographic-algorithms_fig4_330440535

11. Symmetric Crypto System / Single key / Private/
Conventional
http://www.brainkart.com/article/Symmetric-Cipher-Model_8386/

12. Symmetric keys must be created using an RNG that is certified according to
industry standards, such as FIPS 140-2
https://arxiv.org/ftp/arxiv/papers/1904/1904.05528.pdf

13. • Caesar Cipher
C= E(p+3) mod 26 -> C= E(p+K) mod26
P=D(C-3) mod 26 -> P=D(C-K) mod26
haiz KDLC

14. -11 mod 7 = ?
r= -4 add with modulus ie
r= -4 +7
r= 3
• Division Algorithm
a= qn + r
Example
-11 mod 7 = ?
-11 = q*7+r
-11= (-2)*7+ 3
-11=-11
-11 mod 7 = 3

15. Comparison - Symmetric Algorithms
https://www.semanticscholar.org/paper/A-COMPARISON-OF-SYMMETRIC-KEY-ALGORITHMS-DES%2C-AES%2C-Princy/900e50417464460abe15410831b1cf51c0afc5f3

16. https://image.slidesharecdn.com/l-3-blockciphers-150402115310-conversion-gate01/95/block-ciphers-9-638.jpg?cb=1428012295

17. AES
https://www.tutorialspoint.com/cryptography/advanced_encryption_standard.htm

18. Use of Symmetric Algorithms
• Due to the better performance and faster speed of symmetric
encryption (compared to asymmetric), symmetric cryptography is
typically used for bulk encryption / encrypting large amounts of data,
e.g. for database encryption.

19. Asymmetric/ Public key Crypto System/
•
User A – Public Key & Private Key - PUa & PRa
User B – Public Key & Private Key - PUb & PRb

20. Encryption with Public Key
https://www.brainkart.com/article/Principles-of-Public-Key-Cryptosystems-and-its-Applications,-Requirements,-Cryptanalysis_8435/

21. Encryption with Private Key - Digital Signature
https://www.brainkart.com/article/Principles-of-Public-Key-Cryptosystems-and-its-Applications,-Requirements,-Cryptanalysis_8435/

22. Public Key Distribution Scenario
http://www.brainkart.com/article/Distribution-of-Public-Keys_8469/

23. RSA Algorithm
https://www.researchgate.net/figure/Figure-213-The-RSA-Algorithm_fig12_328828460

24. RSA - Example
https://www.chegg.com/homework-help/questions-and-answers/rsa-algorithm-example-1-choose-p-3-q-11-2-compute-n-p-q-3-11-33-3-compute-p-n-p-1-q-1-2-10-q38916858

25. https://keystrokes2016.wordpress.com/2017/01/13/symmetric-and-asymmetric-ciphers-a-comparison/

26. Open source Data Encryption Tools
• 1. BitLocker
• BitLocker is a full-disk encryption tool built-in in the latest Windows
operating systems (Windows 10), which uses AES (128 and 256-bit)
encryption to encrypt data on the drives.
• The Advanced Encryption Standard has been tested and improved
and is now used worldwide by the most security vendors due to its
high level of security and optimization.

27. • Why you should choose BitLocker:
• Easy to use and it’s already integrated into your Windows operating
system, so there’s no need to add another encryption software;
• It’s a free data encryption software tool you can use to prevent data
breaches and data exfiltration from your hard disk.
• It encrypts your entire drive, which makes it impossible for malicious
actors stealing your laptop to remove the hard drive and access your
files.
• When BitLocker Drive Encryption is activated, and you add new files,
BitLocker will encrypt them automatically.

28. • Last Pass
• VeraCrypt
• FileVault2
• 7-Zip
• Disk
• DiskCryptor
• HTTPS Everywhere - HTTPS Everywhere is a Firefox, Chrome, and
Opera extension that encrypts your communications with many major
websites, making your browsing more secure.

29. End-to-End Encryption (E2EE)
End-to-end encryption is the most
secure way to communicate privately
and securely online. By encrypting
messages at both ends of a
conversation, end-to-end encryption
prevents anyone in the middle from
reading private communications.
WhatsApp uses open source Signal
Protocol developed by Open Whisper
Systems (They have their own
messaging application, Signal). Signal
Protocol uses primitives like Double
Ratchet Algorithm, prekeys, Triple
Diffie
Hellman, Curve25519, AES and HMA
C_SHA256.
http://in.c.mi.com/thread-1942739-1-0.html?mobile=no

30. Recent……
• Quantum Cryptography
https://quantumxc.com/quantum-cryptography-explained/

31. • Blockchain
https://www.zignuts.com/wp-content/uploads/2018/05/how-blockchain-work.png

32. Link to download cryptool2
https://www.cryptool.org/en/ct2-downloads

33. Thank You