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Cryptography and Network Security by S. Bose, Ajay Kumar

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Chapter 5

Secure Block Cipher and Stream Cipher Technique

5.1 Need for Double DES and Triple DES

As per DES algorithm, the key size is constrained to only 56-bit thereby brute-force attack can be easily performed in a simple manner. Moreover, linear and differential cryptanalysis illustrates that DES is not an efficient algorithm in terms of providing security to the given plaintext. Therefore, an efficient algorithm was required in compensation with DES algorithm at that point of time to serve many secure Internet protocols. To handle this type of scenario, double DES was introduced by the national institute of standards and technology (NIST). In double DES, two symmetric keys were used for encryption and decryption, however double DES also ...

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