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zmanian/bn.magma

Created September 25, 2016 19:21
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bn.magma
/**
* Compute the apparent security level of BN curves,
* according to Kim-Barbaulecu "Extended Tower Number Field Sieve:
* A New Complexity for the Medium Prime Case" -- CRYPTO 2016.
*/
function ApparentSecLevel(n,c)
k:= 12; //embedding degree of BN Curve
ln_m := k*n*Log(2); ln_ln_m := Log(ln_m);
return Log(2, Exp(c*(ln_m*ln_ln_m^2)^(1/3))); // section 4.1
end function;
c_old := (64/9)^(1/3);
c_new := (32/9)^(1/3);
ApparentSecLevel(256, c_old);
ApparentSecLevel(256, c_new);
ApparentSecLevel(384, c_old);
ApparentSecLevel(384, c_new);
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zmanian commented Sep 25, 2016

Source: https://twitter.com/pbarreto/status/779852921135476738

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