Cryptography is the science of secret writing. It is the science of safe and secure communication.

1. Technical Paper Presentation
TECH-TALK 2014
Topic: Advanced Cryptography and Implementation
Presented By,
Mr. Manish Ambre (144003)
Mr. Akash Jadhav (144024)
CUSROW WADIA INSTITUTE OF TECHNOLOGY,
19, BUND GARDEN ROAD, PUNE-01.

2. Advanced Cryptography And Its
Implementation
Index
1. Introduction
2. What is Cryptography?
3. History

3. Introduction
 Cryptography is the practice of the enciphering and deciphering of messages in
secret code in order to render them unintelligible to all but the intended receiver.
 It is the key technology in secure electronics. Modern cryptography has many
uses, such as to digitally sign documents, for access control, for copyright
protection, etc.
Cryptography is the science of secret writing. It is the science
of safe and secure communication.

4. What is Cryptography?
(An Example)
 Suppose if some one wants to send a message
to a receiver, and wants to be sure that no one
else knows of it.
 However there is a possibility that some one
opens the letter or hears the electronic
communication.
 So the sender converts the message into
unintelligible form (i.e. he encrypts the
message)
 The encrypted message can be decrypted, i.e.
reconverted into its original form only by a key,
which is known to the sender and receiver.
 Without the key, the message cannot be
decrypted.
 Hence the message can only be accessed by the
sender and the receiver only.
Sender
Receiver
Unknown
Person

5. History
 Cryptography has been around for hundreds of years.
 It has been used for different purposes, since when man felt the need of
it.
 It has developed as the time has passed.
 The Roman emperor Julius Ceaser, used basic encryption methods for
his secret messages.
 He used to write the messages in an encrypted form (secret method of
writing).

6. History
 Babington Plot: Cryptography was used in the 1586 plot to assassinate
Queen Elizabeth and put Mary, Queen of Scots on the throne in her
place. Ultimately led to Mary’s execution.
 During the World War II, mechanical and electromechanical ciphers
were used.
 The Nazi Germans used many different methods for protecting their
confidential data.

7. History
The Lorenz cipher
used during WWII
by the Germans

8. Cryptography- Basic Concepts
 Cryptography: It is the art or the science of transforming
intelligible message into one that is unintelligible, and then
retransforming the message back to its original form.
 Plaintext - the original intelligible message
 Cipher text - the transformed message
 Cipher - an algorithm for transforming an intelligible message into
one that is unintelligible by transposition and/or substitution
methods
 Key - some critical information used by the cipher, known only to
the sender & receiver.

9. Cryptography- Basic Concepts
 Encipher (encode) - the process of converting plaintext to cipher text
using a cipher and a key
 Decipher (decode) - the process of converting cipher text back into
plaintext using a cipher and a key
 Cryptanalysis - the study of principles and methods of transforming
an unintelligible message back into an intelligible message without
knowledge of the key. Also called code breaking.
 Authentication - Process of proving one’s identity.

10. Cryptography- Basic Concepts
Plaintext Cipher Text
PlaintextCipher Text
KeyEncrypt Decrypt

11. Cryptographic systems - classification
Cryptographic systems are classified along three dimensions,
1) The type of operations used for transforming plaintext to cipher text
 Substitution
 Transposition
2) The number of keys used
 Single key, symmetric, secret key, conventional
 Two keys, asymmetric, public key
3) The way in which plaintext is processed
 Block cipher
 Stream cipher

12. Encryption and Decryption
 Encryption is the science of changing data so that it is
unrecognizable and useless to an unauthorized person.
 Decryption is changing it back to its original form.
Hello @!*w9
Plain text
Encrypted data

13. Encryption and Decryption
Data
(“Morpheus”)
Encryption
Encrypted Data
(“3*:~>@!w9”)
Key

14. Private Key
 The most secure techniques use a mathematical algorithm and a
variable value known as a 'key'.
 The selected key (often any random character string) is input on
encryption and is integral to the changing of the data. The EXACT
same key MUST be input to enable decryption of the data.
 This is the basis of the protection.... if the key (sometimes called a
password) is only known by authorized individual(s), the data cannot
be exposed to other parties.
 Only those who know the key can decrypt it. This is known as 'private
key' cryptography, which is the most well known form.

15. Cryptographic Methods
 Cryptographic Algorithms generally fall into one of two different
categories, or are a combination of both.
Symmetric1
Asymmetric2
Asymmetric + Symmetric3

16. Cryptographic Methods
Symmetric
 Fast
 Only provides confidentiality
 Need secure channel for key distribution
 Key management headaches from large number of key pairs to
maintain N(N1)/2
 Examples: DES, AES, Blowfish, RC4, RC5

17. Cryptographic Methods
Asymmetric
 Large mathematical operations make it slower than symmetric
algorithms
 No need for out of band key distribution (public keys are
public!)
 Scales better since only a single key pair needed per individual
 Can provide authentication and no repudiation
 Examples: RSA, El Gamal, ECC, Diffie-Hellman

18. Applications of Cryptography
 In particular, the secure exchange
of computer data is of great
importance to banking,
government, and commercial
communications.
 The principles of cryptography
are today applied to the
encryption of fax, television, and
computer network
communications.
Username
Password
Mr. Alex
xxxxxxxxxx

19. ATM and Debit cards
DEBIT CARD
9875 XXXX XXXX XXXX
Mr. Robert
12345
Exp
12/75
The Personal Identity number or PIN that is entered by the
Card owner to perform transactions, along with the card is a
form of cryptography.
The original PIN in plain text format may be with the
owner or can be encrypted on the card itself (cipher text
format).
The PIN is also present in the Bank computers, but is in
cipher text format.
This allows only the user to receive unrestricted access to
his/her bank account, for performing transactions.

20. ATM and Debit cards
Similarly, the communication between the ATM machine, and the
bank’s central computer, is encrypted to prevent anyone from
tapping into the phone lines and recording the signals sent to the
ATM to authorize the dispensing of cash in response to a legitimate
user request and then later feeding the same signals to the ATM
repeatedly to deceive it into dispensing money illegitimately.

21. Lottery Tickets
 Lottery tickets are simply printed on
pasteboard and hence are easily
counterfeited if one knows what to
print on the ticket.
 Each ticket, however, has two
numbers printed on it- one being the
identifying number that will be
announced when a winner is selected
and the other being an encrypted
version of this number.
 Thus, when the winning number is
made known, the would-be
counterfeiter is unable to print an
acceptable encrypted code.
National Lottery
1001 XXXX 0000
XX009 5321 WQRTU
A 123456789
B 987654321
C 000000000
D 999999999
E XXXXXXX
Rs. 100000
Rs. 50000
Rs. 20000

22. Credit Cards
 The Credit Cards have a small
microprocessor built into the card
itself.
 The card and the card reader execute a
sequence of encrypted sign-
/countersign-like exchanges to verify
that each is dealing with a legitimate
counterpart.
 Once this is done, the transaction is
carried out in an encrypted format to
prevent any including the cardholder
or the merchant whose card reader is
involved, from eavesdropping on the
exchange and then later impersonating
either party to defraud the system.
9875 XXXX XXXX XXXX
12345
Exp
12/75
VISACREDIT CARD

23. E-mail
 Email encryption can rely on
public-key cryptography, in
which users can each publish a
public key that others can use to
encrypt messages to them, while
keeping secret a private key
they can use to decrypt such
messages or to digitally encrypt
and sign messages they send.
@

24. E-mail
 Because encryption can be difficult for users, security and
compliance managers at companies and government agencies
automate the process for employees and executives by using
encryption appliances and services that automate encryption.
 Instead overflying on voluntary cooperation, automated
encryption, based undefined policies, takes the decision and the
process out of the users 'hands.
 Emails are routed through a gate way appliance that has been
configured to ensure compliance with regulatory and security
policies.
 Emails that require it are automatically encrypted and sent.