**Post: #1**

Abstract

To encrypt a text _le and to decrypt the encrypted form of the _le to get the original input text _le. This encryption and decryption is done using the most widely used private key encryption scheme based on data encryption standard (DES) adopted in 1977 by National Bureau of Standards.It was designed by IBM based on their own Luci_er cipher and input from NSA.For DES, data are encrypted in 64-bit blocks using a 56-bit key. The algorithm transforms 64-bit input in series of steps into a 64-bit output of cipher text. The same steps, with the same key, are used to reverse the encryption ie. for decryption. Implementation of the algorithm is done using C language.

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