WHAT IS ENCRYPTION :-

Encryption (Round) (cont.) :-

HISTORY OF DE :-

TYPES OF DATA ENCRYPTION :-

Decryption :-

Security And Cryptanalysis :-

KEY OF DATA ENCRYPTION:-

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.

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.

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).

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.

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

they do not adhere to.

Hashing creates a unique, fixed-lengthsignature for a message or data set.

Each “hash” is unique to a specific message, sominor changes to that message would be easyto track.

Once data is encrypted using hashing, it cannotbe reversed or deciphered.

Hashing, then, though not technically anencryption method as such, is still useful forproving data hasn’t been tampered with.

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.

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.

.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).

The same algorithm as encryption. Asymmetricencryption, or public-key cryptography,.

Is different than the previous method because ituses two keys for encryption or decryption (ithas the potential to be more secure as such).

With this method, a public key is freelyavailable to everyone and is used to encryptmessages, and a different, private key is usedby the recipient to decrypt messages.

. Data encryption is a necessity (both for legalreasons and otherwise) when transmittinginformation like PHI, so no matter whatmethod you choose, make sure you’re doingeverything you can to protect data.

Feistily cipher implements Shannon’s S-Pnetwork 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 networkconcept

Achieve diffusion and confusion

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

A signal round DES encryption let ^x represent the

difference of the two known and chosen plaintexts

x1 and x2

^x = x1&

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.

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.

SECRE

T KEY

E{p.k}D{C,K}

CIPHERTEXT(C)

SECRET

KEY

SECRET KEY

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

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 .

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

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)

FIG : public key

William Stallings, Cryptography and

Network Security, 1999.

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