[messaging] Peerio

[Maxwell Krohn]

On Sat, Feb 28, 2015 at 2:46 PM, Trevor Perrin <trevp at trevp.net> wrote:

>
> Back of envelope:
>
> The peerio scrypt parameters (N=2^14, r=8) have been estimated to take
> < 100 milliseconds on a single core of a 2009 Intel processor [1].
> Assuming I can rent cores at ~$0.04/hr [2] = $1/day, that means:
>  - about $1 per 2^20 (~1 million) guesses
>  - about $1K per 2^30 guesses
>  - about $1M per 2^40 guesses
>
>
These costs are probably overestimates, since it's way cheaper
to compute scrypt on GPUs.  I'd recommend using the current litecoin
hashing power / exchange rate to get a decent estimate as to how much
an scrypt guess costs.  The litecoin parameters use
N=2^10,r=1,p=1 [1], so let's say computing Peerio keys is ~64x the price.

But still, trying the math:

According to bitcoinwisdom.com [2], the current litecoin value is 1.79481
USD.
With the current difficulty of 41264, that means you can
expect to make $1.823 an hour if you had a GH/s of hashing power.  So
therefore, you
can expect to make 1.826/(3600)/10^9 dollars per hash, which is about
5.0 *10^{-13} dollars per scrypt.  That's also a reasonable estimate of how
much an scrypt costs on the open market.   Peerio is 64x harder, meaning
each Peerio guess costs about 3.25*10^{-11} dollars.  So if you wanted to
crack a passphrase with 40 bits of entropy, it would cost about $35.69.

These estimates aren't entirely fair, since you probably can't use Litecoin
ASIC
miners to solve Peerio's scrypt.  But still, the CPU-estimates Trevor gave
are likely
off by orders of magnitude.

Sorry in advance for any arithmetic errors.

[1] https://litecoin.info/Block_hashing_algorithm
[2] https://bitcoinwisdom.com/litecoin/difficulty
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