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Practical 2

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Bhavik Sanghar
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24 views3 pages

Practical 2

Uploaded by

Bhavik Sanghar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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240280723022 AC&NS

Practical – 2
Objective: Creating the 16-round keys for the DES (Data
Encryption Standard) encryption algorithm

Steps to Generate the 16 Round Keys for DES:

1. Start with a 64-bit key:


The DES algorithm begins with a 64-bit key, but only 56 bits
are used (the remaining 8 bits are used for parity checking
and are ignored in key generation).
2. Apply the Permuted Choice 1 (PC-1):
 From the 64-bit key, a permutation is applied using
the PC-1 table. This reduces the 64-bit key to a 56-bit
key.
3. Split into Left and Right halves:
 Divide the 56-bit key into two halves: C (28 bits) and D
(28 bits).
4. Generate 16 subkeys:
 For each of the 16 rounds:
1. Left circular shift (LSH): The left and right
halves are shifted by 1 or 2 positions depending on
the round.
2. Apply Permuted Choice 2 (PC-2): The shifted halves
are combined (56 bits) and permuted again using
the PC-2 table to generate a 48-bit subkey.
5. Print keys:
Each of the 16 keys is in 48-bit format and used in the
corresponding DES encryption/decryption round.

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240280723022 AC&NS

Code : Github :)

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240280723022 AC&NS

OUTPUT:

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