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Tutorial B5-2 Breaking DES (Straightforward)

858 bytes added, 18:45, 1 May 2018
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{{Warningbox|This tutorial has been updated for ChipWhisperer 4.0.0 release. If you are using 3.x.x see the "V3" link in the sidebar.}}
 
{{Infobox tutorial
|name = B5-2: Breaking DES (Straightforward)
|image =
|caption =
|software versions =
|capture hardware = CW-Lite, CW-Lite 2-Part, CW-Pro
|Target Device =
|Target Architecture = XMEGA
|Hardware Crypto = No
|Purchase Hardware =
}}
 
 
Follow the same procedure as in : [[Tutorial B5 Breaking AES (Straightforward)]], but:
* # Flashing the DES firmware to the target device (i.e.g. chipwhisperer/hardware/victims/firmware/simpleserial-des/simpleserial-des-xmega.hex), instead;# Setting an appropriate 'Total Samples' (e.g. 3500) and 'Offset' (e.g. 15500) in the ''Scope Settings'';# Setting the 'Key Length (Bytes)', 'Input Length (Bytes)' and 'Output Length (Bytes)' to 8 bytes in the ''Target Settings'';# Setting an appropriate 8 bytes Key in the ''Generic Settings (e.g. 2B 7E 15 16 28 AE D2 A6)''. * Or, alternatively, execute the script "setup_cwlite_xmega_des.py" to perform steps 2-4 (you still need to perform step 1 yourself). In the Analyzer, you'll need to modify the script to call the DES model instead of the AES model. This will mean: <pre>from chipwhisperer.analyzer.attacks.models.DES import DES, SBox_output</pre> And setting: <pre>leak_model = DES(SBox_output)</pre> See the example analyzer script for a complete listing of the required commands.
and:* Setting an appropriate 'Total Samples' and 'Offset' in Note that the ''Scope Settings'';* Setting attack attemps to recover the 'Key Length [[wikipedia:File:DES-key-schedule.png|first round key]], which only has 48bits (Bytes[[wikipedia:File:DES-f-function.png|8 s-boxes x 6 bits each]])', 'Input Length while the original key has 56 significative bits (Bytes64 if we count the parity bits that are irrelevant)' and 'Output Length (Bytes)' . So, if we map the first round key, obtained after the attack, to 8 bytes in the ''Target Settings'';* Setting an appropriate 8 bytes Key in original key (you can use the ''Generic Settings''provided DES Key Schedule Tool to do it), there will still be 8 bits missing (256 combinations).
* Or, alternatively, execute the script "ChipWhisperer-Lite[[File: DES SimpleSerial on XMEGA" to do the above steps automatically in this platformdeskeyschedulecalc.png]]
In the Analyzerthis example, it matches the only difference is to set the 'Crypto Algorithm' to DES in the ''Attack Settings''.original key that was:
[[File:breaking_deskey_des.png|896x896px801x801px]]
Note that the attack attemps to recover the [[wikipedia:File:DES-key-schedule.png|first round key]], which only has 48bits ([[wikipedia:File:DES-f-function.png|8 s-box x 6 bits each]]), while the original key has 56 significant bits (64 if we count the parity bits that are irrelevant). So, if we map the first round key, obtained after the attack, to the original key (you can use the provided DES Key Schedule Tool to do it), there will still be 8 bits missing (256 combinations).== Links ==
{{Template:Tutorials}}[[FileCategory:deskeyschedulecalc.png|800x800pxTutorials]]