The seminar covered cryptography, including its definition as using Greek words for "hidden" and "writing" to securely transmit information. Cryptography provides confidentiality, integrity, and availability via techniques like encryption, decryption using keys, hashing and symmetric/asymmetric algorithms. Symmetric cryptography uses a single shared key for encryption and decryption while asymmetric uses public/private key pairs. Hashing transforms data to a fixed-length code for integrity checks.

1. Seminar on
Cryptography
Submitted by – Anmol Bansal
Roll Number – 195098
Department – CSE
Faculty – Dr. Priyanka Rathee Date – 26-04-2022

2. What we will cover?
1. What is Cryptography?
2. Its Applications
3. Its Benefits
4. Its Types
5. Symmetric Key Cryptography
6. Asymmetric Key Cryptography
7. and Hashing

4. Cryptography
Cryptography is the combination of two greek words Kryptos and Graphein.
Kryptos having the meaning hidden and Graphein having the meaning Writing.
Cryptography is a method of securing communications through some
protocols in order to make the information secure or
understandable only by the sender and the receiver.
It provides Confidentiality(i.e. privacy), Integrity(i.e. there was no
modification during the transition) and Availability(i.e. users have
access to the systems and the resources). It is commonly known as
the CIA triad.

5. Applications
• For Storing Passwords, via Hashing
• In End-to-end encryption for text messaging

6. Benefits of Cryptography
• Message Confidentiality (or privacy): Only an authorized recipient
should be able to extract the contents of the message from its encrypted
form.
• Message Integrity: The recipient should be able to determine if the
message has been altered (which is implemented with the help of hash
functions).
• Sender Authentication: The recipient should be able to verify from the
message, the identity of the sender, so as to validate claims from
emitter.
• Sender Non-Repudiation: The emitter should not be able to deny
sending the message.

7. Some Terminology
• Cipher text – Cipher text is the scrambled text transformed from
plaintext using an algorithm.
• Encryption – The process of converting plain text into an
unintelligible format (i.e. cipher text) is called Encryption.
• Decryption - The process of converting cipher text into a plain
text is called Decryption.
• Key – A key is a variable value that is applied using an algorithm to
a string or block of unencrypted text to produce encrypted text,
or to decrypt encrypted text.

8. Types of Cryptography
1. Symmetric Key Cryptography (or Secret/Private
Key Cryptography)
2. Asymmetric Key Cryptography (or Public Key
Cryptography)
3. Hashing

10. Symmetric Key Cryptography
Symmetric encryption is the method of securing data. The reason why it’s
called “symmetric” is because it’s a process that involves the use of a
single key by communicating parties to encrypt and decrypt the data.
Advantages - The most significant advantage when it comes to the
symmetric encryption method is its simplicity. As it has only one key doing
encryption and decryption, symmetric encryption algorithms are
considered the fastest and require less computational power to perform.
Disadvantages - The receiver needs to get the secret key from the sender.
Algorithms – AES, DES(i.e. Data Encryption Standard), 3DES

11. How encryption works for symmetric key cryptography?
1. The sender uses an
encryption key (usually
a string of letters and
numbers) to encrypt
their message.
2. The encrypted
message, called cipher
text, looks like
scrambled letters and
can’t be decrypted by
anyone along the way.
3. The recipient uses a
decryption key to
transform the cipher text
back into readable text.

12. Question - How many encryption keys are required
to implement a symmetric algorithm with N
participants?
Answer - ⁿC₂
Explanation –
Since every communicating pair in the
system should have a unique key. Thus the
number of keys required to connect N
parties using symmetric cryptography is
given by the formula: (N * (N-1)) / 2.

13. Asymmetric Key Cryptography
Asymmetric encryption involves the use of multiple keys for data
encryption and decryption. To be exact, the asymmetric encryption
method consists two encryption keys that are mathematically related to
each other. These keys are known as the public key and private key.
Advantages - Security is increased since the private keys don't ever have to
be transmitted or revealed to anyone.
Disadvantages – It is slower and requires more computational power
because of its complexity.
Algorithms - RSA

14. How encryption works for asymmetric key cryptography?
1.Asymmetric
encryption uses a
mathematically related
pair of keys for
encryption and
decryption: a public key
and a private key.
2.If the public key is
used for encryption,
then the related private
key is used for
decryption.
3.If the private key is
used for encryption,
then the related public
key is used for
decryption.

15. Question - How many encryption keys are required
to implement an asymmetric algorithm with N
participants?
Answer – 2N
Explanation –
Each time a new user is added to the system, it needs only one
public key and one private key. Thus, for n users, we have 2N keys.

16. Hashing
Hashing is the process of transforming large sized data into a small
sized code of a fixed length via the use of hash functions.
The process of hashing is different from encryption as hashing is
irreversible.
Some of the hash functions are – SHA256 and SHA512 i.e. Secure
Hash Algorithm.

18. Conclusion
• We use either private key cryptography or public key cryptography
according to our requirement.
• If we want to send messages quickly we use private key algorithm
and if we want to send messages secretly we use public key
algorithm.

19. References
• www.tutorialspoint.com
• www.slideshare.net
• www.researchgate.net
• www.wordpress.com
• www.sectigostore.com
• www.wikipedia.com
• www.youtube.com
• www.cs.utexas.edu
• www.medium.com
• www.geeksforgeeks.org
• www.analyticssteps.com
• learn.saylor.org
• crypto.stackexchange.com

20. Thank You
Any Query?