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Tomu, a tiny ARM microprocessor which fits in your USB port

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Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#51

Post by dtornabene »

lisper wrote: post #21
dtornabene wrote: post #3

Earlier quoted context omitted.

thats ultimately the intent, to build a Yubikey-like security key, with everything open down through the firmare to the details of the soc

You should check out: https://sc4.us/hsm/index.html (Disclosure: this is my project.)

this is really cool! thanks for sharing it here, I'll definitely dig in deeper on it. I've been following Tomu development for over a year now (two?) I've got one on desk right now, the ideas that mithro cares about, the open hardware, are very important to me and I'm glad to see as much development in the space as possible.

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#53

Post by ZiiS »

ecesena wrote: post #44
dtornabene wrote: post #3

Earlier quoted context omitted.

thats ultimately the intent, to build a Yubikey-like security key, with everything open down through the firmare to the details of the soc

If size doesn't matter, U2F Zero [1] is an open u2f security key. And we're about to unveil the upgrade to fido2... Edit: added link [1] https://u2fzero.com

Here is my more compact layout [1]. Twice the Tomu, but at a certain point that just makes it easier to extract. The big advantage of tomu's size is you can leave it in a laptop port, but that is the last thing you want to do with a security device.

[1] https://github.com/BarnabyShearer/u2f-zero

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#55

Post by vardump »

pkaye wrote: post #30
askvictor wrote: post #10

Earlier quoted context omitted.

One key (pardon the pun) requirement of a 2FA key is that it can't be cloned - how would this be prevented? Can the microprocessor be locked to prevent reading its flash memory?

Years back I used to work for a company that built 8051 clones. It was possible to prevent the microprocessor from reading the flash memory because the 8051 has a separate program memory and data memory space.

I don't understand how that helps to prevent reading anything.

8051 can read data from both CODE and XDATA memory spaces.

See: http://www.keil.com/support/man/docs/is51/is51_movc.htm

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#56

Post by sametmax »

askvictor wrote: post #10
dtornabene wrote: post #3

Earlier quoted context omitted.

thats ultimately the intent, to build a Yubikey-like security key, with everything open down through the firmare to the details of the soc

One key (pardon the pun) requirement of a 2FA key is that it can't be cloned - how would this be prevented? Can the microprocessor be locked to prevent reading its flash memory?

Genuine question: if you can't clone your 2FA, how do you make spares like a house key ? If there is way to get a spare, what's the way to deal with key loss or shared access ?

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#57

Post by jon-wood »

sametmax wrote: post #56
askvictor wrote: post #10

Earlier quoted context omitted.

One key (pardon the pun) requirement of a 2FA key is that it can't be cloned - how would this be prevented? Can the microprocessor be locked to prevent reading its flash memory?

Genuine question: if you can't clone your 2FA, how do you make spares like a house key ? If there is way to get a spare, what's the way to deal with key loss or shared access ?

You don’t make a copy, you add an extra key. (Almost?) all services that support 2FA keys allow you to add multiple keys.

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#58

Post by dspillett »

sametmax wrote: post #56
askvictor wrote: post #10

Earlier quoted context omitted.

One key (pardon the pun) requirement of a 2FA key is that it can't be cloned - how would this be prevented? Can the microprocessor be locked to prevent reading its flash memory?

Genuine question: if you can't clone your 2FA, how do you make spares like a house key ? If there is way to get a spare, what's the way to deal with key loss or shared access ?

Essentially you have a to configure the account/device you are authenticating with to accept multiple keys permanently (so you can have spares) or temporarily (replacing a key by registering a new one then revoking the old).

In the case of key loss on a properly secure service registering a new key could be problematical if you don't have any other key that is still appropriately registered - you might be permanently locked out unless there is an admin function who has a key registered so can do it for you.

Look at multi-key options for encrypted filesystem for one way that this can work. Often the filesystem or block device has a symmetric key that is in turn encrypted by each of the keys that you wish to be able to open it. It is the same symetric key every time, though you can't unlock my copy of it with your key nor can I unlock your's. Once unlocked we could both add a third user by encrypting the base key with their public key (PKI is not required, but is not uncommon).

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#59

Post by PinguTS »

bsder wrote: post #15
askvictor wrote: post #10

Earlier quoted context omitted.

One key (pardon the pun) requirement of a 2FA key is that it can't be cloned - how would this be prevented? Can the microprocessor be locked to prevent reading its flash memory?

Newer microcontrollers like the Microchip(nee Atmel) SAM-L11 are implementing ARM TrustZone with hardware security features.

Secure as in CLKSREW?

Re: Tomu, a tiny ARM microprocessor which fits in your USB port

#60

Post by boomlinde »

CoolGuySteve wrote: post #40
utopcell wrote: post #2

Neat little device, looks like a Yubikey clone. One could get a similar device by hacking a Logitech unifying receiver, which contains a ..16MHz 8051 clone in it, and a radio to spare.

I feel old knowing my Logitech USB receiver is roughly as powerful as the Gameboy Advance I bought in college.

At roughly the same clock speed I think the 32-bit ARM7 in the Gameboy would actually run laps around an 8-bit 8051.
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