// #eevblog — 2021-07-08
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00:12:24 <EEVBot> [Twitter] - eevblog - OMG this is EPIC level BULLSHIT! https://t.co/uLECT8bC9L https://t.co/SnChqlyWOC https://t.co/uiGnZIFDBP
00:14:48 <hsn> https://www.knowlescapacitors.com/getattachment/f15ce7eb-e225-4ef9-936c-2c4ea683a3f2/Border-Cap.aspx
00:15:01 <hsn> thats the capacitor i want to use
00:15:19 <hsn> +-20% @ 10pF value
00:16:27 <K> wth is that
00:16:41 <K> how does it get soldered, actually
00:16:54 <electrohead> very carefully
00:16:56 <electrohead> lol
00:20:42 <hsn> K, Benefits
00:20:51 <hsn> Tighter control on dimensions
00:20:58 <hsn> Facilitates pick and place – thus reducing handling damage
00:21:39 <K> (mumbles something uninteligable)
00:22:17 <hsn> it comes from know less dielectric labs
00:22:35 <hsn> knowlescapacitors.com
00:22:36 <hsn> xD
00:23:42 <hsn> look at their catalogue page c2
00:23:43 <hsn> https://media.digikey.com/pdf/Data%20Sheets/Knowles%20Dielectric%20Labs%20PDFs/SLC_Caps_Cat_2018.pdf
00:25:35 <K> to solder these you need some extra step for wire bonding too?
00:26:01 <K> or this is some joke i am not smart enough to follow
00:29:19 <hsn> i dont know .. im afraid to make jokes when its for high specialized application that im zilch at
00:29:20 <hsn> :D
00:36:03 Join: TheDude ([email protected]) to #EEVblog
00:39:11 <TheDude> \o
00:40:01 * Ampera hugs TheDude
00:40:03 <Ampera> how are you?
00:40:13 <TheDude> hey
00:40:15 <TheDude> doing alright
00:40:35 <TheDude> managed to code AES-128 in octave today at work :D
00:40:46 <Ampera> That's uh
00:40:48 <Ampera> ah thing
00:40:54 <TheDude> :D
00:41:02 <electrohead> o/
00:41:07 <Ampera> I'm implementing all of ArcGIS in C#
00:41:25 * Ampera hugs electrohead
00:41:27 <Ampera> how are you?
00:41:29 <TheDude> we need encryption for seed&key for UDS communication over CAN
00:41:39 <Ampera> yeah but why make your own implementation
00:41:46 <Ampera> when someone else's is going to be less of a risk
00:41:53 * electrohead hugs Ampera
00:41:55 <TheDude> the libraries that can be found online want a fair chunk of the stack
00:41:55 <electrohead> good man, you?
00:42:09 <TheDude> because expanding the key is usually done all at once
00:42:19 <TheDude> and stack is scarce on the embedded platform that we have
00:42:30 <TheDude> so I studied the algorithm and am now implementing my own
00:42:32 <Ampera> At least you have a practical reason
00:42:44 <TheDude> first step to try and understand it was to knock it out in octave
00:42:52 <TheDude> now I'm writing it in C
00:43:27 <Ampera> Surely there's a lightweight AES implementation in C
00:43:33 <TheDude> I'm sure there is
00:43:42 <TheDude> but my main goal is to learn something, not just get it done
00:43:52 <Ampera> I'd seek one out, because rolling your own encryption is very risky
00:44:04 <TheDude> nah
00:44:23 <TheDude> it'll be fine
00:44:37 <K> sure
00:44:38 <Ampera> Yes. Geniuses who think they know everything do that in a lot of consumer shit, and it's one great way how data breaches happen.
00:44:45 <K> how bad an in be?
00:44:53 <TheDude> not very bad
00:45:13 <Ampera> It all depends on how bad the consequence of it being breached is, paired with the likelihood that someone will do so
00:45:14 <TheDude> like I said, this is just to give access to the configuration of the motor controller
00:45:19 <K> it is not like he is implmeneting his own algo
00:45:49 <TheDude> also you can test the algorithm fairly thoroughly on a PC
00:45:50 <K> with propper test suite the code itself will be fine, probably
00:46:07 <TheDude> feed it a shitton of random plaintexts
00:46:09 <Ampera> why are you encrypting it over CAN though
00:46:24 <TheDude> and run the same thing on the microshaft library and compare
00:46:37 <Ampera> That's testing to work, not testing to be secure.
00:46:47 <K> i think there are semi-official test data sets
00:46:51 <Ampera> Bigger giants have made larger mistakes.
00:46:59 <TheDude> okay so UDS is the protocol used on automotive shit
00:47:16 <Ampera> yeah, but if it's a vehicle who cares about encryption
00:47:31 <TheDude> we use it to configure our motor controllers
00:47:47 <TheDude> so in order to be able to actually configure something, you need to enter a diagnostic session
00:48:01 <TheDude> and you do that by requesting a seed from the server (motor controller)
00:48:12 <TheDude> it gives you a pseudorandom number
00:48:26 <TheDude> you do encryption on that and send the cipher back
00:48:37 <Ampera> but why
00:48:38 <TheDude> if it matches the one calculated inside, you get access to that session
00:48:59 <TheDude> because you don't want random people to fuck around with the controller configuration duh
00:49:01 <Ampera> I'm not saying you shouldn't, I'm wondering why you deem it necessary
00:49:14 <Ampera> no I'm saying I'm lacking context here
00:49:17 <TheDude> the stakeholder specification
00:49:28 <Ampera> if it's all self contained inside a vehicle, the only person who can fuck with it to that level is probably the owner
00:49:29 <TheDude> that's what they're asking for, that's what we're implementing
00:49:36 <Ampera> alright
00:49:43 <TheDude> we have different access levels, actually
00:49:59 <Ampera> then the reason is external, no problem
00:50:13 <TheDude> we're providing the manufacturer their access level
00:50:30 <TheDude> and we have one for ourselves which is unlocked further
00:51:05 <TheDude> also you have things like the ignition timer and the odometer in the motor controller
00:51:38 <TheDude> a shady owner might try to knock those down in order to obtain a better resale value, for example
00:51:50 <Ampera> that's the case on any car
00:51:55 <TheDude> right
00:52:03 <TheDude> and that's why those access levels are locked by default
00:52:18 <Ampera> someone could easily fuck with the display, do something else, there's ways around that
00:52:32 <TheDude> ofc
00:52:42 <TheDude> we're just covering our part of the system
00:53:43 <TheDude> anyhow
00:54:10 <TheDude> I only need to implement the encryption, not decryption
00:54:20 <TheDude> as the thing is only ever going to be used one way
01:46:39 * T3sl4 ciphers TheDude
01:51:00 Join: Kuschelpony ([email protected]) to #EEVblog
01:52:49 * electrohead films
01:59:48 * rust_collector falmpfs
02:07:34 <Ampera> Funniest clip ever: https://youtu.be/nsU-FNO_p7w?t=475
02:07:34 <EEVBot> [Title] - Youtube: Idiots In Cars 29
02:12:57 Join: arch ([email protected]) to #EEVblog
02:30:06 Join: DogWomble_ ([email protected]) to #EEVblog
02:31:21 Quit: DogWomble ([email protected]) Ping timeout: 121 seconds
02:55:06 Join: DogWomble ([email protected]) to #EEVblog
02:56:08 Quit: DogWomble_ ([email protected]) Ping timeout: 121 seconds
03:20:18 Join: modrobert ([email protected]) to #EEVblog
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03:31:30 Quit: Ysjoelfir_BNC ([email protected]) Ping timeout: 121 seconds
03:32:57 <arch> can i buy shit directly from TI? fucking digikey is price gouging like crazy
03:33:06 <arch> that's my waifu they're holding hostage
03:34:04 <rust_collector> sure you can
03:35:05 <arch> like 80% of the ICs i get are TI, so i want to get them directly and save money. the rest i can get from Arrow or digikey (less preferable)
03:37:33 <rust_collector> just register, and buy stuff
03:38:23 <arch> goddamn, only 2 ics available in stock. wtf.
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