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Small-factor IFP

Finding small prime factors

Find a prime divisor p of an integer N; running time can depend on p independently of the bitlength of N.

Heuristic · dependence on smallest factor

Expected small-factor cost, including polynomial arithmetic overhead in log N

1 results · 1 papers
Classical randomizedHeuristicN with smallest prime divisor pLp[1/2,c] · poly(log N)
#PUBLICATION / AUTHORSDATETIME BOUNDSPACE BOUNDEVIDENCE
1Factoring integers with elliptic curvesHendrik W. Lenstra Jr.Annals of Mathematics 1987SourceBibTeX / detailsNov 1987Lp[1/2, sqrt(2)] (log N)2Not extracted from the sourcePublishedSource checked
Comparison definition & assumptions
Regime
Expected small-factor cost, including polynomial arithmetic overhead in log N
Computation
Classical randomized
Rigor
Heuristic
Instances
N with smallest prime divisor p
Cost scale
L_p[1/2,c] · poly(log N)
Parameter
p
Description
Expected cost is parameterised by the least prime factor p, not by N. Here L_X[α,c] = exp((c+o(1))(ln X)^α(ln ln X)^(1−α)); all logarithms in this definition are natural.
Comparison rules
Expected cost is parameterised by the least prime factor p, not by N. Here L_X[α,c] = exp((c+o(1))(ln X)^α(ln ln X)^(1−α)); all logarithms in this definition are natural. Only compare entries with this cost scale, input domain and computational model. Polynomial and quasi-polynomial expressions without an extracted scalar are not ranked.
Tags
elliptic curve method, small prime factors, heuristic