[tahoe-dev] "Elk Point" design for mutable, add-only, and immutable files

[David-Sarah Hopwood]

David-Sarah Hopwood wrote:
> I've designed a new version of the cap protocol I posted a few days
> ago, that addresses Brian's comments about roadblock attacks.
[...]
> A conservative choice of parameters might be
> 
>   immutable: n = 128, t = 128, ell = 160, m = 160.
>              read caps 256 bits, verify caps 320 bits, read/verify 228 bits.

I meant: read/verify caps 288 bits.

>              2^128 confidentiality and collision resistance; roadblock
>              attacks are effectively impossible.
> 
>   mutable:   n = 128, t = 50,  ell = 160, m = 160.
>              read caps 178 bits, verify caps 320 bits, read/verify 228 bits.

Same here: read/verify caps 288 bits.

>              2^128 confidentiality; collision resistance not relevant.
>              Resistance to roadblock attacks is sufficient provided
>              strategy 2 described below is used.

-- 
David-Sarah Hopwood  ⚥  http://davidsarah.livejournal.com