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A comment on Show HN: The SC4-HSM, a fully open USB hardware secure module. Parent comment

Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo... by Karunamon on Friday July 08, 2016 @11:54AM (#12056382)
I thought that the whole point of a smartcard is that your keys, once loaded, can never be extracted again, even by the host. Rather than passing secrets to the host directly, there's a miniature PKI that does request/signature, secured by a password, using a hardware pinpad if you're very serious.

Little window for error too, since screwing up the password some small number of times results in the card being blocked, and in some cases, destroyed.

Even if the host is running hostile code, the worst it could do is forge signing requests?

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Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo... by lisper on Friday July 08, 2016 @12:05PM (#12056491)
> screwing up the password

If the host machine is pwned then it's not hard to steal your password.

> the worst it could do is forge signing requests

Well yeah, that's true. But if the card is protecting a really sensitive asset (like your bitcoin account) then a single forged request can do an awful lot of damage.

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Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo... by Karunamon on Friday July 08, 2016 @12:17PM (#12056622)
The point being that the malware either has to horn in on a legitimate request (and I'm not sure if that's possible or not given how PKI), or issue its own request, which the user has to authorize with password, ideally out of band using a hardware pinpad.
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Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo... by lisper on Friday July 08, 2016 @12:30PM (#12056727)
> ideally out of band using a hardware pinpad

Not "ideally". Critically. Without an out-of-band PIN the card is easy to compromise. And most cards don't have input devices.

And even with a secure PIN entry, without a display you can't actually know what transaction you are authorizing. So yes, the malware would have to "horn in" on a legitimate request. But if your machine is pwned that's not hard.

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