Auditing an offline wallet

[Roy Badami]

Well, firstly, the ways of verifying that an address is correct have been much discussed, but this doesn't help me much retrospectively.  I can't see any way of determining that I haven't been subject to such an attack in the past, except to audit my balance.

Secondly, for a savings wallet in which I pay small amounts in on a regular basis, the risk is that in 10 years time I will discover that the small amount of coins I thought I was paying into my savings wallet every month aren't there.

If I don't discover such an attack for 3 months, I really haven't lost much in the way of savings.  So a regular audit woudl work for me.  Sure, for someone who regularly receives payments of large numbers of coins, additional precautions are necessary.  But that's a very small minority of users.

[Roy Badami]

To say, you shouldn't care what your balance is as long as you can convince yourself that you haven't been the subject of the particular attacks you think likely is, well bizarre.

That is a mischaracterization.  Have fun.

Well, I realise I must be misunderstanding your position.  But you seemed to be repeatedly telling me that I shouldn't want to verify my balance.  I'm sorry but I want to verify my balance.  It's not the only thing I want, but it is one of the things I want.

[tl121]

If you want to know your balance you can get it from a computer that you trust. You input your public seed to "recover" your wallet.  It would have to run the appropriate bitcoin software for your wallet.  In addition to trusting the bitcoin software, you would have to trust the operating system, the CPU, the memory,  the BIOS, most of the peripherals, etc...  If you read and understood all the source code for all of this software you still wouldn't be safe.  You would need to trust the compiler used to compile this source code and the compiler used to compile the compiler, etc.  There is simply no way of getting around this situation. To do any kind of secure computation, you have to have a "trusted computing base". 

http://en.wikipedia.org/wiki/Trusted_computing_base

From a practical perspective your best bet is a clean install of all of the software and then running that, reacquiring the complete block chain, etc.   If you are worried about this machine being hacked, you can build an operating system that boots from DVDrom and includes all of the necessary software, starting over each time you want to check.  But even then you will need to trust that your hardware (and BIOS) have not been hacked, not to mention the possibility that someone managed to get into your safe and swap the DVD ROM.

There is no limit to the amount of time one can waste worrying about these questions if computer security is one's vocation or avocation. Come to think of it, this time may not be wasted if one has a sufficient number of bitcoins. :-)

[Brangdon]

You can get the cold wallet to display its addresses. Type those addresses into a block-chain explorer via a browser on a machine that isn't compromised. Probably a random cyber-cafe machine would do. This is more practical if you are willing to reuse the same address, so you only have one to check.