Re: [9fans] thoughs about venti+fossil - Plan9

This is a discussion on Re: [9fans] thoughs about venti+fossil - Plan9 ; On Mar 4, 2008, at 8:00 PM, Enrico Weigelt wrote: > some thoughts about venti that go around in my mind: > > 1. how stable is the keying ? sha-1 has only 160 bits, while > data blocks may ...

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Thread: Re: [9fans] thoughs about venti+fossil

  1. Re: [9fans] thoughs about venti+fossil

    On Mar 4, 2008, at 8:00 PM, Enrico Weigelt wrote:
    > some thoughts about venti that go around in my mind:
    >
    > 1. how stable is the keying ? sha-1 has only 160 bits, while
    > data blocks may be up to 56k long. so, the mapping is only
    > unique into one direction (not one-to-one). how can we be
    > *really sure*, that - even on very large storages (TB or
    > even PB) - data to each key is alway (one-to-one) unique ?


    http://www.nmt.edu/~val/review/hash/index.html

    Not that this analysis is without flaws, though.

    Thanks,
    Roman.


  2. Re: [9fans] thoughs about venti+fossil

    > On Mar 4, 2008, at 8:00 PM, Enrico Weigelt wrote:
    > > some thoughts about venti that go around in my mind:
    > >
    > > 1. how stable is the keying ? sha-1 has only 160 bits, while
    > > data blocks may be up to 56k long. so, the mapping is only
    > > unique into one direction (not one-to-one). how can we be
    > > *really sure*, that - even on very large storages (TB or
    > > even PB) - data to each key is alway (one-to-one) unique ?

    >
    > http://www.nmt.edu/~val/review/hash/index.html
    >
    > Not that this analysis is without flaws, though.


    have you invented the 9fans.net effect?

    this link may or may not be similar. but it is on point:
    http://www.valhenson.org/review/hash.pdf

    do you care to elaborate on the flaws of this analysis?

    - erik

  3. Re: [9fans] thoughs about venti+fossil

    On Mar 4, 2008, at 8:43 PM, erik quanstrom wrote:

    >> On Mar 4, 2008, at 8:00 PM, Enrico Weigelt wrote:
    >>> some thoughts about venti that go around in my mind:
    >>>
    >>> 1. how stable is the keying ? sha-1 has only 160 bits, while
    >>> data blocks may be up to 56k long. so, the mapping is only
    >>> unique into one direction (not one-to-one). how can we be
    >>> *really sure*, that - even on very large storages (TB or
    >>> even PB) - data to each key is alway (one-to-one) unique ?

    >>
    >> http://www.nmt.edu/~val/review/hash/index.html
    >>
    >> Not that this analysis is without flaws, though.

    >
    > have you invented the 9fans.net effect?


    Meaning? I guess the reference went over my head.

    > this link may or may not be similar. but it is on point:
    > http://www.valhenson.org/review/hash.pdf


    I believe it to be exactly the same paper.

    > do you care to elaborate on the flaws of this analysis?


    I tend to agree with counter arguments published here:
    http://monotone.ca/docs/Hash-Integrity.html
    I'm not an expert in this field (although I dabbled
    in cryptograhy somewhat given my math background) and
    thus I would love if somebody can show that the
    counter arguments don't stand.

    Thanks,
    Roman.

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