The document discusses encryption, detailing its definition, history, types, and importance in data security. It covers symmetric (private-key) and asymmetric (public-key) cryptography, along with key concepts like hashing and Feistel cipher structures. It emphasizes the necessity of encryption methods to ensure the confidentiality and integrity of transmitted information.

2.  WHAT IS ENCRYPTION :-
 Encryption (Round) (cont.) :-
 HISTORY OF DE :-
 TYPES OF DATA ENCRYPTION :-
 Decryption :-
 Security And Cryptanalysis :-
 KEY OF DATA ENCRYPTION:-

3.  Encryption is a technique for transforming
information on a computer in such a way that it
becomes unreadable.
 Encryption is the process of obscuring
information to make it unreadable without
special knowledge.
 A secure computing environment would not be
complete without consideration of encryption
technology.

6.  DEs was the result of research project set up by
International Business Machines (IBM).
 corporation in the late 1960’s which resulted in
a cipher know as LUCIFR in the early it was
decided to commercialise LUCIFER and a
number of significant. Changes were
introduced.
 Published in 1977, standardized in 1979.
 Key: 64 bit quantity=8-bit parity+56-bit key
 In 1971, IBM developed an algorithm, named
which operates on a block of using a key.

7.  In 1971, IBM developed an algorithm, named
which operates on a block of 64 using a key
 Walter Tuchman, an IBM researcher, refined
LUCIFER and reduced the key size to ,fit on a
chip.
 In 1977, the results of Tuchman’s project of
IBM was adopted as the by NSA (NIST).

8.  DES (and most of the other major symmetric
cipher) is based on cipher know as the festal
block cipher.
 This was block cipher developed by the IBM
cryptography research Horst feistily in the
early 70’s. it consists of a number rounds
where each round contains bit-suffering, non-
linear substitution (s-boxe) and exclusive or
operation.
 Most symmetric encryption schemes today are
based on this structure knows as a feistily
network.

9.  Once a plain-text message is received to be
encrypt.
 it is arranged into 64 bit blocks required for
input if the number.
 In this the message of bits in the message is
not evenly dividable by 64 then the last block.
 will be padded multiple permutation and
substitutions are incorporated throughout in
order to increase the difficulty of performing a
cryptanalyst is on the cipher.
 However it is generally accepted that the initial
and final permutation offer title or no
contribution to the security of DES and in fact
some software unit implementation then
although strictly speaking these are not DES as

10.  Hashing creates a unique, fixed-length
signature for a message or data set.
 Each “hash” is unique to a specific message, so
minor changes to that message would be easy
to track.
 Once data is encrypted using hashing, it cannot
be reversed or deciphered.
 Hashing, then, though not technically an
encryption method as such, is still useful for
proving data hasn’t been tampered with.

11.  Symmetric encryption is also known as
private-key cryptography, and is called so
because the key used to encrypt and decrypt.
 the message must remain secure, because
anyone with access to it can decrypt the data.
 Using this method, a sender encrypts the data
with one key, sends the data (the cipher text)
and then the receiver uses the key to decrypt
the data.

12.  Asymmetric encryption, or public-key
cryptography, is different than the previous method
because.
 it uses two keys for encryption or decryption (it has
the potential to sec such).
 With this method, a public key is freely available to
everyone and is used to encrypt messages, and a
different, private key is used by the recipient to
decrypt messages.
 Any of these methods would likely prove sufficient
for proper data security, and a quick Google search
will reveal the multitude of software available for
data encryption.

13.  .Data encryption is a necessity (both for legal reasons
and otherwise) when transmitting information like
PHI, so no matter what method you choose, make
sure you’re doing everything you can to protect data.
 Asymmetric encryption is most commonly used
to secure physically separate end points.
Examples include:
 Web browser and web server (HTTPS).
 VPN client and server.
 Secure FTP (SSL encrypted connection).

14.  The same algorithm as encryption. Asymmetric
encryption, or public-key cryptography,.
 Is different than the previous method because it
uses two keys for encryption or decryption (it
has the potential to be more secure as such).
 With this method, a public key is freely
available to everyone and is used to encrypt
messages, and a different, private key is used
by the recipient to decrypt messages.
 . Data encryption is a necessity (both for legal
reasons and otherwise) when transmitting
information like PHI, so no matter what
method you choose, make sure you’re doing
everything you can to protect data.

16.  Feistily cipher implements Shannon’s S-P
network concept.
based on invertible product cipher
 Process through multiple rounds which
 partitions input block into two halves
 perform a substitution on left data half
 based on round function of right half & sub key
 then have permutation swapping halves
 Feistel cipher implements Shannon’s S-P network
concept
 Achieve diffusion and confusion

18.  Although more information has been on the
Cryptanalysis of dfs than any other block
cipher while having a theoretical complicity
less than a brute force attack.
 The most practical attack to date is still abrate
foree approach .the length of the key
determines the number of possible.
 Differential cryptanalysis has been proposed
since 1990 to break block cipher such as DES
and while successful for breaking LUCIFER

19.  A signal round DES encryption let ^x represent the
difference of the two known and chosen plaintexts
x1 and x2
 ^x = x1&

20.  A mentioned earlier there are two main types
of cryptography in use today secret key or
Private key cryptography and public key
cryptography key cryptography
 the oldest type wheres asymmetric
cryptography is only being used publicly since
the late 1970’s asymmetric.
 The was major milestone in the search for a
perfect encryption scheme.
 There are two types of Key Private Key &
public key.

21.  Private Key also called as the secret key.
 This cryptography goes back to least encryption
times and is of Concern
 here it involves the use of only one key which is
used for both encryption and decryption (hence the
use of the term symmetries).
 It is necessary for security purpose that the secret
key never be revaluated.

22. SECRE
T KEY
E{p.k}
D{C,K}
CIPHERTEXT(C)
SECRET
KEY
SECRET KEY

23.  Private/secret/single key cryptography uses
one key .
 Shared by both sender and receiver.
 If this key is disclosed communications are
compromised .
 Also is symmetric, parties are equal .
 Hence does not protect sender from receiver
forging a message & claiming is sent by sender

24.  It also referred as a symmetric encryption. It
two gets in that security key private key or yes
and public key.
 Sender user a security key to enciphers
message and sends to receiver when the
recipient get the message .
 he uses public key of sender to descript the
message it is most secure message than
sematic one because sender need not discover
this private key .

25. A public-key, which may be known by
anybody, and can be used to encrypt
messages, and verify signatures
a private-key, known only to the recipient,
used to decrypt messages, and sign (create)
signatures
Asymmetric because those who encrypt
messages or verify signatures cannot
decrypt messages or create signatures
Probably most significant advance in the
3000 year history of cryptography

26.  Public-Key algorithms rely on two keys with
the characteristics that it is:
 Computationally infeasible to find decryption
key knowing only algorithm & encryption key
 Computationally easy to en/decrypt messages
when the relevant (en/decrypt) key is known
 Either of the two related keys can be used for
encryption, with the other used for decryption
(in some schemes)

27. FIG : public key

28.  William Stallings, Cryptography and
Network Security, 1999.
 https: www.google.com
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