Unit 3-Symmetric Key Crypto_Part14

Unit 3-Symmetric Key Crypto_Part14 - (NBS) The National...

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Unit 3 - 27 Feistel Cipher To decrypt run the process backward. For i = n, n − 1 , . . . , 1, the decryption rule is The final result is the original plaintext: Any round function F will work in a Feistel cipher, provided that the output of F produces the correct number of bits. But only secure for certain functions F R i −1 = L i L i −1 = R i F(R i −1 , K i ) P = (L 0 , R 0 )
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Unit 3 - 28 Data Encryption Standard In the mid- 70’s the US government decided that a powerful standard cipher system was necessary.
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Unformatted text preview: (NBS) The National Bureau of Standards put out a request for the development of such a cipher. Several companies went to work and submitted proposals. The winner was IBM with their cipher system called Lucifer. With some modifications suggested by (NSA) the National Security Agency, in 1977, Lucifer became known as the Data Encryption Standard or DES. It has since been replaced by the Advanced Encryption Standard (AES)...
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Unit 3-Symmetric Key Crypto_Part14 - (NBS) The National...

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