I implemented the algorithm published in ECC Brainpool to generate
random elliptic curves.
http://tools.ietf.org/html/draft-lochter-pkix-brainpool-ecc-02#page-21

Need to calculate an optimal way to solve in sage de point 4 and 8 of
the algorithm

   The following procedure is used to generate the parameters A and B
of
   a suitable elliptic curve over GF(p) and a base point G from a
prime
   p of bit length L and a 160 bit seed s.

   1.   Set A = find_integer_2(s).

   2.   Convert h to an integer A.

   3.   If - 3 = A* Z^4 is not solvable, then set s = update_seed(s)
and
        goto Step 1.

   4.   Compute one solution Z of - 3 = A* Z^4.

   5.   Set s = update_seed(s).

   6.   Set B = find_integer_2(s).

   7.   If B is a square mod p, then set s = update_seed(s) and goto
        step 6.

   8.   If 4*A^3 + 27*B^2 = 0, then set s = update_seed(s) and goto
Step
        1.


Thanks.

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