Use num_traits::pow to efficiently compute random mu_k values for prover #27
Description
As of #26, the prover tediously computes the mu_l exponent for each index l in his proof. This could be optimized in future work to use a more efficient exponentiation algorithm (e.g. square and add), compute each mu_l in a single iterative computation, or both.
As it happens, num_traits::pow exists for just this purpose, and would be the ideal solution to this problem. Unfortunately, curve25519-dalek does not implement the necessary num_traits::identities traits. The ideal solution to this problem, would involve implementing num_traits for curve25519-dalek and submitting a patch upstream.
Alternatively, I could consider wrapping the Scalar type into a local Wscalar type, and implement the traits locally. This is not ideal, but may be quicker than pushing changes upstream.