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NYarvin's profile
Norman Yarvin
Norman Yarvin
Norman Yarvin
@NYarvin

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Norman Yarvin

@NYarvin

yarchive.net/blog
Joined April 2013

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    1. Matthew Green‏ @matthew_d_green 20 Mar 2018
      • Report Tweet
      • Report NetzDG Violation

      Good morning Twitter. This post about Ledger cryptocurrency hardware wallet vulnerabilities is extremely cool, and not just for cryptocurrency people. Let me talk a bit about it. 1/https://saleemrashid.com/2018/03/20/breaking-ledger-security-model/ …

      29 replies 810 retweets 1,507 likes
      Show this thread
    2. Matthew Green‏ @matthew_d_green 20 Mar 2018
      • Report Tweet
      • Report NetzDG Violation

      There is a common architectural theme in certain embedded devices: they incorporate a secure processor (or processor component) to protect critical secrets or ensure correct behavior. I’ve seen this in all kinds of devices, not just cryptocurrency wallets. 2/

      1 reply 9 retweets 47 likes
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    3. Matthew Green‏ @matthew_d_green 20 Mar 2018
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      (For an obvious example, every recent iPhone has a Secure Enclave processor that stores your fingerprint data and cryptographic keys. But these devices are used elsewhere as well. https://www.theiphonewiki.com/wiki/Secure_Enclave …) 3/

      1 reply 6 retweets 44 likes
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    4. Matthew Green‏ @matthew_d_green 20 Mar 2018
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      Secure co-processors typically incorporate some kind of tamper-resistant physical casing as well as a limited interface to protect secret data. They often have some crypto functions on board, and can “attest” (prove to remote parties) that they’re running the right software. 4/

      1 reply 6 retweets 42 likes
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    5. Matthew Green‏ @matthew_d_green 20 Mar 2018
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      None of these processors can withstand all attacks. But let’s ignore that part and assume they can, for the moment. This still leaves a huge gaping hole in many devices. 5/

      1 reply 4 retweets 37 likes
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    6. Matthew Green‏ @matthew_d_green 20 Mar 2018
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      You see, the typical “secure element” isn’t powerful enough to drive your entire device (including the pretty GUI and peripherals and network communication if that’s available). So most devices have a second “insecure” processor to do all that stuff. 6/

      3 replies 8 retweets 41 likes
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      Norman Yarvin‏ @NYarvin 20 Mar 2018
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      Replying to @matthew_d_green

      You're being too kind to them. Driving the display and buttons is the only really critical feature, and for the sort of tiny display on a Ledger, you can do that even from the wimpiest Arduino. Not using the secure CPU for that is just being lazy.

      12:20 PM - 20 Mar 2018
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      0 replies 0 retweets 1 like

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