Quote from: shorena on November 08, 2014, 04:18:27 PM

Quote from: KidPoker on November 08, 2014, 03:35:05 PM

-snip-

So if your private keys are air gapped and if even using a usb to sign transactions isn't 100% safe, what is the alternative to signing transactions from an offline computer?

#1 QR Code, e.g. the bither app uses them
#2 sound [1]
#3 type the TX by hand, which is IMHO the safest way, unless your brain was hacked [3]. That level of security is almost never needed. On the other hand its not that hard unless you create a TX with 100 outputs/inputs. The nasty part would be the signed TX, which is just hex code and typos can happen easily.
#4 floppy [2]
#5 CD/DVD which is costly and has the similar problems USB has

Edit: In case this wasnt clear, I think for the majority of bitcoin users an USB stick is fine to transport data from cold to hot wallet. Not everyone needs/has a tinfoil hat.

[1] https://bitcointalk.org/index.php?topic=735111.0
[2] https://bitcointalk.org/index.php?topic=813295.0
[3] http://www.turnkeylinux.org/files/images/blog/i-know-kung-fu.jpg

What a fantastic post. The sound option is fascinating to read about. Thanks a lot!