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Get bit representation of an elliptic curve group element

asked 2018-12-03 11:38:55 +0200

panther gravatar image

updated 2018-12-16 18:40:52 +0200

FrédéricC gravatar image

I can define an elliptic curve using

E = EllipticCurve(GF(97), [2,3])

I can then compute a group on E using

G = E.abelian_group()

I can then sample a random element in the group using

R = G.random_element()

Is there a way I can get a bit string representation of this group element R? Actually, I am implementing a pseudo-random generator scheme, which finally outputs a group element on elliptic curve. I need to convert it to a bit string.

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FrédéricC gravatar imageFrédéricC ( 2018-12-03 21:22:56 +0200 )edit

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answered 2018-12-11 02:10:42 +0200

dan_fulea gravatar image

I tried:

sage: E = EllipticCurve(GF(97), [2,3])
sage: P = E.random_point()
sage: P
(22 : 5 : 1)
sage: x, y, z = P
sage: x, y, z
(22, 5, 1)
sage: bin(x), bin(y), bin(z)
('0b10110', '0b101', '0b1')
sage: ZZ(x).binary(), ZZ(y).binary(), ZZ(z).binary()
('10110', '101', '1')

Note that since $97$ is not a power of two, there is no structural path from the random point (components) to the binaries... It is just a way to "(en)code" the data.

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Asked: 2018-12-03 11:38:55 +0200

Seen: 485 times

Last updated: Dec 11 '18