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*To*: tor-talk@xxxxxxxxxxxxxxxxxxxx*Subject*: Re: [tor-talk] NSA supercomputer*From*: Seth David Schoen <schoen@xxxxxxx>*Date*: Fri, 5 Apr 2013 14:57:20 -0700*Delivered-to*: archiver@xxxxxxxx*Delivery-date*: Fri, 05 Apr 2013 17:57:37 -0400*Dkim-signature*: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=eff.org; s=mail2; h=In-Reply-To:Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID:Subject:To:From:Date; bh=M4FhBC+US4VFWYv+OvpM7GMuaiRK4VUlPTMLY5F8vnQ=; b=FEq6Ofd6W3J5NcgcjQF27gjcrwaaGdajgIyLyKkaxqcw/MUH485iyn18c/h082OU0AXDJLBsmNWiTCC8nweW3aXkoaWQgBDRx0rUKkO1xjeBslnDnR+2OhdsVxK/H1rP;*In-reply-to*: <CAMnnSdjGHqrsnL3u+TkSPPyAbhzes+cmh+NGanbW_p2g2a2Jhw@xxxxxxxxxxxxxx>*List-archive*: <http://lists.torproject.org/pipermail/tor-talk>*List-help*: <mailto:tor-talk-request@lists.torproject.org?subject=help>*List-id*: "all discussion about theory, design, and development of Onion Routing" <tor-talk.lists.torproject.org>*List-post*: <mailto:tor-talk@lists.torproject.org>*List-subscribe*: <https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk>, <mailto:tor-talk-request@lists.torproject.org?subject=subscribe>*List-unsubscribe*: <https://lists.torproject.org/cgi-bin/mailman/options/tor-talk>, <mailto:tor-talk-request@lists.torproject.org?subject=unsubscribe>*References*: <CAB0qP14kjvxhy0D0+vqbK6J1xMDy_gA9nKe9JfHgxLmiO9Fnnw@xxxxxxxxxxxxxx> <CABbQNJoSi6Xx=q5+5Ue979Yn=YtfMV9hPDP3mJkUHKDJg9aOLw@xxxxxxxxxxxxxx> <515E75FC.3040204@xxxxxxxxx> <CAL3oi7auEh=MxEJ9=C=BTxxD1GrjTTUbZurwL6r0N01w67y9bA@xxxxxxxxxxxxxx> <CAD2Ti2-M2D545FAy2mxTioCT7gNt=G-o9RLDZF5Kxd5=GRc+TA@xxxxxxxxxxxxxx> <CACotuh4GE5FSQVX+iY-+=M5BbFJQH2xoSax+GCwqPU8JiS3zpw@xxxxxxxxxxxxxx> <20130405080046.GT6172@xxxxxxxxx> <CAMnnSdiWTKKmby_dtgbi2QbWQto3AJT41a69DLA-mVKi6nnTHA@xxxxxxxxxxxxxx> <CAAS2fgTyE-MNd5k4m6Vh7=y48MHNRBpQHZTaLVwFiFsKVFuZFg@xxxxxxxxxxxxxx> <CAMnnSdjGHqrsnL3u+TkSPPyAbhzes+cmh+NGanbW_p2g2a2Jhw@xxxxxxxxxxxxxx>*Reply-to*: tor-talk@xxxxxxxxxxxxxxxxxxxx*Sender*: tor-talk-bounces@xxxxxxxxxxxxxxxxxxxx*User-agent*: Mutt/1.5.21 (2010-09-15)

Andrew F writes: > So lets look at this from another view. How fast does a computer have to > be to fully bruit force a 64,128,256 key? ZettaFlops? YottaFlops? > http://en.wikipedia.org/wiki/Flops Lets assume a classical > computer. > > George, crankup that abacus of yours and let us know. I for one would be > very interested. > Or anyone else with big fat calculator? My is the wimpy drugstore kind... As Gregory pointed out, "flops" is not the right measurement here because cryptographic operations are not floating-point operations. Checking a candidate key doesn't involve any floating-point math, but rather something like a block cipher decryption, which is a different sort of computation. The calculations to figure out brute-force speeds are really about simple multiplication and division. Just as the distance traveled by a moving object is given by distance = speed Ã elapsed time the number of decryptions attempted by a brute force search is given by decryptions = speed Ã elapsed time For example, if you have a 128-bit symmetric key, and you want to talk about a situation in which every possible key value has been checked, the relationship is 2ÂÂâ = speed Ã elapsed time or, if you prefer, 340282366920938463463374607431768211456 = speed Ã elapsed time If you want the time, just divide 2ÂÂâ by the speed. If you want the requisite speed to finish in a specified time, just divide 2ÂÂâ by that time. You just need to use consistent units, like measuring speed in trial decryptions per second and measuring elapsed time in seconds. In 1998 EFF built a brute-force cracking machine https://en.wikipedia.org/wiki/EFF_DES_cracker which "was capable of testing over 90 billion keys per second", against the DES system which used 56-bit keys. To find the time it would take that machine to be sure of testing every possible key, just divide 2ââ by 90 billion; the answer is given in seconds. (To convert seconds to days, divide by 86400.) -- Seth Schoen <schoen@xxxxxxx> Senior Staff Technologist https://www.eff.org/ Electronic Frontier Foundation https://www.eff.org/join 815 Eddy Street, San Francisco, CA 94109 +1 415 436 9333 x107 _______________________________________________ tor-talk mailing list tor-talk@xxxxxxxxxxxxxxxxxxxx https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk

**Follow-Ups**:**Re: [tor-talk] NSA supercomputer***From:*Seth David Schoen

**References**:**Re: [tor-talk] NSA supercomputer***From:*George Torwell

**Re: [tor-talk] NSA supercomputer***From:*george torwell

**Re: [tor-talk] NSA supercomputer***From:*Alexandre Guillioud

**Re: [tor-talk] NSA supercomputer***From:*grarpamp

**Re: [tor-talk] NSA supercomputer***From:*Gregory Disney

**Re: [tor-talk] NSA supercomputer***From:*Eugen Leitl

**Re: [tor-talk] NSA supercomputer***From:*Andrew F

**Re: [tor-talk] NSA supercomputer***From:*Gregory Maxwell

**Re: [tor-talk] NSA supercomputer***From:*Andrew F

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