That will help make a clear Concept About Cryptography that use in modern era

1. 10/05/2018
Prepared by…….

2.  Cryptography is a method of storing and transmitting data in a
particular form so that only those for whom it is intended can
read and process it.
C = Ek(P)
P = Dk(C)
where P = plaintext, C = cipher text, E = the encryption method,
D = the decryption method, and
k = the key.

3. The word is derived from the Greek kryptos meaning hidden and
“gráphein”- “to write”

4.  A modern cipher was use by Julius Caesar (100 BC to 44 BC), who did not
trust his messengers when communicating with his governors and officers.
For this reason, he created a system in which each character in his
messages was replaced by a character three positions ahead of it in the
Roman alphabet.
 A perfect Example of Cryptography is Enigma. That’s use during world
war ii by Adolf Hitler, to communicate with Nazi army. There are approx
158,962,555,217,826,360,000 nearly 159 quintillion

6. • Data Privacy(confidentiality)
• Data Authenticity(it came from from where it
claims)
• Data integrity(it has not been modified on the
way) in the digital world
• Non-repudiation:
A mechanism to prove that the sender really
sent this message.

7.  Plaintext
 Encryption Algorithm
 Cipher text.
 Decryption Algorithm
 Encryption Key
 Decryption Key

8.  Plaintext
the original, unencrypted text that requires encryption like
email files databases credit card details any sensitive data.
 Encryption Algorithm & Decryption Algorithm
There are various type of Encryption Algorithm like
• RSA(Ron Rivest, Adi Shamir, and Leonard Adleman)
• DES(Data Encryption Standard)
• AES(Advanced Encryption Standard)

9.  Cipher text:
The encryption process uses algorithms to encrypt
data. There are two main ways these algorithms
process this data:
 stream cipher : one bit or one byte at a time
 block cipher : Blocks of 64, 128, 192 or 256 bits at a Time

11. Encryption Key/Decryption Key
A cryptographic key is a string of bits used by a cryptographic
algorithm to transform plain text into cipher text or vice versa
 Public Key:
A public key may be placed in an open access directory for
decryption of the digital signature of the sender, the public key
of the message recipient encrypts the sender’s message.
 Private Key:
A private key is shared only with the key's initiator, ensuring
security.

12. Fundamentally, there are two types of cryptosystems
based on the manner in which encryption-decryption
is carried out in the system
 Symmetric Key Encryption
 Asymmetric Key Encryption
 Hash Functions

13.  The encryption process where same keys are used for
encrypting and decrypting the information is known as
Symmetric Key Encryption. Example- AES , DES ,3DES.

14. The encryption process where different keys are used for
encrypting and decrypting the information is known as
Asymmetric Key Encryption. Example -RSA , DIFFLE.

15.  Hash functions, also
called message
digests and one-way
encryption, are algorithms
that, in essence, use no key
.Instead, a fixed-length hash
value is computed based upon
the plaintext that makes it
impossible for either the
contents or length of the
plaintext to be
recovered. Hash algorithms
are typically used to provide
a digital fingerprint of a file's
contents . Example – MD(128
bit).SHA-1(160 bit).

16.  Digital Signatures
◦ Where the comes form right person or not.
 Electronic Money( Cryptocurrency)
◦ Like –Bitcoin , Litecoin , Ethereum .
 Secure Network Communications
o Developed Secure Socket Layer (SSL) for providing data security
layered between TCP/IP such as HTTP, or FTP. SSL supports data
encryption, server authentication, message integrity, and client
authentication for TCP/IP connections.

17. Security in the Internet is improving. The increasing use of the
Internet for commerce is improving the deployed technology to
protect the financial transactions
Cryptography may be groovy technology, but since security is a
human issue, cryptography is only as good as the practices of
the people who use it. Users leave keys lying around, choose
easily remembered keys, don't change keys for years. The
complexity of cryptography effectively puts it outside the
understanding of most people and so motivation for the
practices of cryptographic security is not available
Do you have any questions about cryptography that I didn’t
answer? Any best practices you have used to protect yourself
from threats?

18.  https://www.cl.cam.ac.uk/~jac22/books/mm/book/node352.
html
 http://www.laits.utexas.edu/~anorman/BUS.FOR/course.mat/S
Sim/life.html
 https://www.tutorialspoint.com/cryptography/benefits_and_dr
awbacks.htm
 http://www.umsl.edu/~siegelj/information_theory/projects/de
s.netau.net/Cryptography%20and%20goals.html
 http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/Web/5264/
other/5264_encryption_overview_text_pop.html
 https://blog.storagecraft.com/5-common-encryption-
algorithms
 https://www.techopedia.com/definition/16139/public-key
 http://www.cs.du.edu/~snarayan/crypt/vigenere.html

19. THE END