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I'm trying to write a code to perform encryption and decryption of 64-bit DES but I'm having a problem in verifying that my code is working correctly. My graduation project is about DES crypt-analysis so I'm trying to implement DES to generate the pairs used in the attack.

Can anyone give me an example on encryption of DES with all stages?

For instance, I would like to see the key schedule and the values of all 16 round keys generated by the input key.

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    $\begingroup$ Just download a working DES code and check with it? $\endgroup$
    – kelalaka
    Commented Dec 19, 2018 at 19:22
  • $\begingroup$ @siba36 Note that DES has a 56-bit key, not 64-bits. The LSB in each byte is not part of the key. $\endgroup$
    – zaph
    Commented Dec 26, 2018 at 17:13

3 Answers 3

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Might I suggest the "DES cipher internals in Excel" page by Nayuki? Because everything's in Excel, all the internal values are openly displayed.

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There's also Eugene Styer's Javascript DES Example (mirror of university course, original is down) which can be (re-)modified to allow using any key:

623c623
<         <td><input name="key" value="0000000000000000" size="25" type="text"></td>
---
>         <td><input name="key" value="3b3898371520f75e" readonly="readonly" size="25" type="text"></td>
627c627
<         <td><input name="keyb" value="0000000000000000" size="25" type="text"></td>
---
>         <td><input name="keyb" value="922fb510c71f436e" readonly="readonly" size="25" type="text"></td>

by removing the readonly attribute (also shows the default keys set to all zeros, supports triple DES as well). You'd save the page and make the above modifications then open the saved page JS-DES.html in a browser.

A copy of the original code allowing the keys to be set can be extracted from the google code dpades source architecture.

The code is found from the decompressed archive by path dpades/trunk/simu_js, extracting JS-DES.html and collocated image directory JS-DES_fichiers. JS-DES.html can be opened in a browser. (The entire archive is 37 MB, Google quit showing the expanded code trees when google code was archived.)

It seems a bit of lesson plan laziness using a fixed key to prevent students from 'cheating' on assignments.

There's also a set of DES validation triplets derived from FIPS Special Pub 500-20 Appendix B: The DES Test Set (Also found on the Internet Archive.)

The triplets are available on github. There may be a single key parity error, I don't recall if I left it corrected. I used the triplets to verify the original libcrypt DES implementation in the early '90s and modified that code to output all the round values. Using JS-DES.html is a bit more convenient (and it passes the validate test set as well).

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The example plaintext given in Handbook of Applied Cryptography is the ascii bytes of "Now is the time for all ". Here's a trace through the first block of that, 4E6F772069732074. The key is 0123456789ABCDEF and expected ciphertext 3FA40E8A984D4815:

     input: 4E6F7720-69732074
after perm: B7A48736-00FE1327
==== Round 01/16
  using subkey: 0B02679B49A5
     after xor: 8B159B9120AB
    after sbox: 1B7A1DBA
       after P: 7E4B644F
      xor with: B7A48736
    xor result: C9EFE379
         final: 00FE1327-C9EFE379
==== Round 02/16
  using subkey: 69A659256A26
     after xor: 8C9906D501D5
    after sbox: CF430076
       after P: C2DBC430
      xor with: 00FE1327
    xor result: C225D717
         final: C9EFE379-C225D717
==== Round 03/16
  using subkey: 45D48AB428D2
     after xor: A595815EC07D
    after sbox: 467DACD6
       after P: D71390FD
      xor with: C9EFE379
    xor result: 1EFC7384
         final: C225D717-1EFC7384
==== Round 04/16
  using subkey: 7289D2A58257
     after xor: 7D5E2A9FFE5F
    after sbox: 815B7DE2
       after P: B4D764C9
      xor with: C225D717
    xor result: 76F2B3DE
         final: 1EFC7384-76F2B3DE
==== Round 05/16
  using subkey: 3CE80317A6C2
     after xor: 063FA64DD83E
    after sbox: 08700318
       after P: 0E292004
      xor with: 1EFC7384
    xor result: 10D55380
         final: 76F2B3DE-10D55380
==== Round 06/16
  using subkey: 23251E3C8545
     after xor: 2933B496F945
    after sbox: F053CADD
       after P: 9FF58A23
      xor with: 76F2B3DE
    xor result: E90739FD
         final: 10D55380-E90739FD
==== Round 07/16
  using subkey: 6C04950AE4C6
     after xor: 992C9B95DB3D
    after sbox: 871AC376
       after P: 47F66470
      xor with: 10D55380
    xor result: 572337F0
         final: E90739FD-572337F0
==== Round 08/16
  using subkey: 5788386CE581
     after xor: 7D613EF61A21
    after sbox: 8D9454C2
       after P: 249E5119
      xor with: E90739FD
    xor result: CD9968E4
         final: 572337F0-CD9968E4
==== Round 09/16
  using subkey: C0C9E926B839
     after xor: A5751B93AF30
    after sbox: 4ACA1D90
       after P: 7249A149
      xor with: 572337F0
    xor result: 256A96B9
         final: CD9968E4-256A96B9
==== Round 10/16
  using subkey: 91E307631D72
     after xor: 01485229C880
    after sbox: E212A54D
       after P: 4DD0AAA8
      xor with: CD9968E4
    xor result: 8049C24C
         final: 256A96B9-8049C24C
==== Round 11/16
  using subkey: 211F830D893A
     after xor: 611DD0EDCB63
    after sbox: 5C3145A1
       after P: 840CAC1F
      xor with: 256A96B9
    xor result: A1663AA6
         final: 8049C24C-A1663AA6
==== Round 12/16
  using subkey: 7130E5455C54
     after xor: 211BE95A0959
    after sbox: 2C7AF9D0
       after P: 375D22D5
      xor with: 8049C24C
    xor result: B714E099
         final: A1663AA6-B714E099
==== Round 13/16
  using subkey: 91C4D04980FC
     after xor: 4B2C7939940F
    after sbox: A84C6034
       after P: 028D16E0
      xor with: A1663AA6
    xor result: A3EB2C46
         final: B714E099-A3EB2C46
==== Round 14/16
  using subkey: 5443B681DC8D
     after xor: 043CE0145E80
    after sbox: 0DFA245D
       after P: 0E5949FC
      xor with: B714E099
    xor result: B94DA965
         final: A3EB2C46-B94DA965
==== Round 15/16
  using subkey: B691050A16B5
     after xor: 69BB5EDF3DBE
    after sbox: 998F9E88
       after P: B9E8514B
      xor with: A3EB2C46
    xor result: 1A037D0D
         final: B94DA965-1A037D0D
==== Round 16/16
  using subkey: CA3D03B87032
     after xor: 457D0507D868
    after sbox: AA2BE869
       after P: D9DC0EC4
      xor with: B94DA965
    xor result: 6091A7A1
         final: 1A037D0D-6091A7A1
after perm: 3FA40E8A-984D4815
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  • $\begingroup$ Hey Andrew and welcome. Thanks for taking the time to post that! $\endgroup$
    – Maarten Bodewes
    Commented Mar 13 at 14:27

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