network security using des algorithem
DESCRIPTION
network security algorithemTRANSCRIPT
Network Security With
DES Algorithm
Submitted By:Drashti Vadaviya
(201304101510011)M.Tech 1st SEM
CGPIT
Submitted To:Prof. Trunal Patel
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Security
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Symmetric key algorithms
The first class of encryption algorithm is Symmetric Key Algorithm because they use the same key for encryption and decryption.
Cryptographic algorithms can be implemented in either hardware (for speed) or in software (for flexibility).
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Example
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Data Encryption Standards
In January 1977, the U.S. Government adopted a product cipher developed by IBM as its official standard for unclassified information. This cipher, DES (Data Encryption Standard), was widely adopted by the industry for use in security products. It is no longer secure in its original form, but in a modified form it is still useful.
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Data Encryption Standards
The algorithm, which is parameterized by a 56-bit key has 19 distinct stages.The first stage is a key-independent transposition on the 64-bit plaintext. The last stage is the exact inverse of this transposition. The stage prior to the last one exchanges the leftmost 32 bits with the rightmost 32 bits. The remaining 16 stages are functionally identical but are parameterized by different functions of the key.
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Shift
The operation of one of these intermediate stages is illustrated in Fig. Each stage takes two 32-bit inputs and produces two 32-bit outputs. The left output is simply a copy of the right input. The right output is the bitwise XOR of the left input and a function of the right input and the key for this stage, Ki.
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Key Generation
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F(Ri,Ki)
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Limitation
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Triple DES
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Conclusion
DES key size is too short for proper security.
Also , DES uses 64-bit blocks, Which raises some potential issues when encryption several GB of data with the same key.
3DES is a trick to reuse implementations, by cascading three instances of DES(with distinct keys).
3DES is believed to be secure, but it is slow.
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References
[1] Andrew S. Tannenbaum, “computer networks” Fourth Edition.[p.780]
[2] Behrouz A. Forouzan, “Data Communication and Networking” Fourth Edition.[p.935]
[3] Hasan Mathkour , “ A secured cryptographic messaging system” , International conference on machine Lerning and computing,2011.
[4] Dr. Brain Gladman, “ A Specification For Rijndael, the AES Algorithm”, v3.1, 3rd march 2001.
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