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Data Encryption Tayyab Arif Allama Iqbal Open Unviersity Pakistan Book: Telecommunication Primer BS(cs) 7 th Semster Mob: 00923445064252
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Data encryption, Description, DES

Dec 21, 2014

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Mohammad Tayyab

Telecommuncations Primer Signals, Building Blocks and Networks.
Data Encryption & Description, DES, Single and Two key Concept
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Page 1: Data encryption, Description, DES

Data Encryption

Tayyab ArifAllama Iqbal Open Unviersity PakistanBook: Telecommunication PrimerBS(cs) 7th SemsterMob: 00923445064252

Page 2: Data encryption, Description, DES

Encryption Definition: The action of disguising information so that

it can be recovered easily by the persons who have the key, but is highly resistant to recovery by persons who do not have the key.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 3: Data encryption, Description, DES

A message is cleartext (plaintext) is encrypted (disguised) through the use of an encryption key to create a Ciphertext.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 4: Data encryption, Description, DES

The encryption key may be changed from time to time to make an intruder’s task more difficult.

Restoration of a ciphertext to cleartext is achieved by the action of decryption using a decryption key.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 5: Data encryption, Description, DES

In symmetric (Single key):The encryption and decryption keys are the

same.

In asymmetric (two keys):The encryption and decryption keys are

different.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 6: Data encryption, Description, DES

Encryption Methods: Encryption is accomplished by scrambling

the bits, characters, words, or phrases in the original message. Scrambling involves two activities:

Transposition Substitution

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 7: Data encryption, Description, DES

Transposition: In which the order of the bits patterns,

characters, words or phrases is rearranged.

Substitution: In which new bit patterns, characters, words,

or phrases are substituted for the originals without changing their order.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 8: Data encryption, Description, DES

Data Encryption Standard (DES):Most widely used algorithmPioneered by IBM It is symmetric cryptosystemDeveloped to protect sensitive, unclassified,

US government, Computer data.Used to provide authentication of electronic

funds transfer messages.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 9: Data encryption, Description, DES

DES Algorithm:

The algorithm accepts plaintext, P, and performs an initial permutation, IP, on P producing P0, The block is then broken into left and right halves, the Left (L0) being the first 32 bits of P0 and the right (R0) being the last 32 bits of P0.

With L0 and R0, 16 rounds are performed until L16 and R16 are generated.

The inverse permutation, IP-1, is applied to L16R16 to produce ciphertext C.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 10: Data encryption, Description, DES

Public Key Cryptosystem It is an asymmetric cryptosystem. First announced in 1976. Offer a radically different approach to

encryption. The idea depends on the use of a pair of keys

that differ in a complementary way. Several algorithms are proposed RSA algorithm is considered to be highly

secure.

Tayyab Arif 00923445064252, Allama Iqbal Open University

Page 11: Data encryption, Description, DES

Public key encryption can achieved:

PrivacyAuthentication

Page 12: Data encryption, Description, DES

Tayyab Arif

Allama Iqbal Open Unviersity PakistanBook: Telecommunication Primer

BS(cs) 7th SemsterMob: [email protected]

www.youtube.com/tayyab8632