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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">A este doplnim:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Ak si budete drzat databazu privatnych klucov u seba a viete skotrolovat<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">duplikovane zariadenia v sieti, jedine co bude moct attaker urobit je, ze nahradi<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">uz dodane zariadenie svojim. Kluce by mali byt samozrejme generovane nahodne<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">a dostatocne velke aby sa nedali uhadnut.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">j.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Hw-list [mailto:hw-list-bounces@list.hw.cz]
<b>On Behalf Of </b>Zuffa Jan<br>
<b>Sent:</b> Monday, September 25, 2017 3:07 PM<br>
<b>To:</b> HW-news<br>
<b>Subject:</b> RE: Elektronicke autorizace zarizeni - algoritmy<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Dobry den,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Okremtoho, ze pouzijete nejaky chalenge – response algoritmus, minimalne by bolo vhode zabezpecit<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">aby kazde zo zariadeni malo svoj privatny kluc. Najjednoduchsie ma napada ze bude korelovat so seriovym cislom zariadenia.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Teda pre vas to bude znamenat ze na zaciatku si vyziadate seriove cislo, nasledne poslete chalenge a vycitate response.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Alebo si budete drzat databazu privatnych klucov u seba.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">j.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Hw-list [<a href="mailto:hw-list-bounces@list.hw.cz">mailto:hw-list-bounces@list.hw.cz</a>]
<b>On Behalf Of </b>Karel M<br>
<b>Sent:</b> Monday, September 25, 2017 2:48 PM<br>
<b>To:</b> HW-news<br>
<b>Subject:</b> Elektronicke autorizace zarizeni - algoritmy<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Pekny den, mam zarizeni, ktere ma v sobe MCU s vnitrni EEPROM, kde jsou ulozeny parametry zarizeni, komunikace s vnejskem je po RS485. Zarizeni neni trvale napajeno a jde tedy resetovat, nema informaci o datu a case.<o:p></o:p></p>
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<p class="MsoNormal">Co bych potreboval nove udelat, je nejaky sikovny algoritmus pro autentizaci tohoto zarizeni, tedy ze se v nem nachazi nami vyrobena elektronika. Predstava je takova, ze se posle nejaky paket s pseudonahodnym slozenim, zarizeni to pomoci
nejakeho algoritmu prepocte a posle zpet.<o:p></o:p></p>
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<p class="MsoNormal">Zajima me priklad nejakeho algoritmu vhodneho pro MCU a jak osetrit utok hrubou silou, kdyz zarizeni jde resetovat, nepamatuje si tedy v case chybne pokusy.
<o:p></o:p></p>
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<p class="MsoNormal">Samozrejme je tu jeste priklad, kdy zarizeni bude kopie a paralelne k nemu na RS485 elektronika z naseho zarizeni (treba ze starsiho jinak zniceneho), to ale asi osetrit nejde.<o:p></o:p></p>
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<p class="MsoNormal">za tipy diky<o:p></o:p></p>
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<p class="MsoNormal">Karel<o:p></o:p></p>
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