Let q be a generator of a cyclic group = {1, 2, …, p − 1} of order p − 1 and y = q^{x} (modulo p).
Proposition 14.5 (The IndexCalculus Algorithm): Initialization: Select a factor base = {p_{1}, p_{2}, …, p_{s}} consisting of elements of . is chosen so that a significant proportion of the elements of can be expressed in the form with n_{i} ≥ 0.
14.5a  Select a random k with 0 ≤ k < n and compute q^{k} (modulo p). 
14.5b 
Try to write q^{k} (modulo p) as a product with c_{i}, ≥ 0:

14.5c  Repeat Steps 14.5a–b until a sufficient number of linear relations as above are found in order to solve the system of equations to determine ... 
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