I want to see if a technique like Dixon's method for integer factorization would work for discrete logs. If the base is 2 (which could be generalized), to find the log of r, set up equations like the following (in which the first 7 primes are the factor base):
rAi12Ai23Ai35Ai47Ai511Ai613Ai717Ai8≡1 mod p
Then use row operations on the rows of the matrix A to find a linear combination of these rows with 0s in every entry other than the first two. This gives an equation of the form rx2y≡1 mod p, from which it's easy to obtain the log of r base 2.
The question I have is, whether the row operations can be performed so x and y are non-zero mod p−1. I don't have much idea how to guarantee this, and there is a strong tendency to get 0s. For example, I picked p=4327 and r=1277, and generated a matrix A in which each row satisfies
1277Ai12Ai23Ai35Ai47Ai511Ai613Ai717Ai8≡1 mod 4327
A=[1−1−11−30001−3−210−110111−1001−11−10−1002001−150−10−1−112030−1−1−11320−1−1−1111−2−220−11]
Lo and behold, the determinant of A is 0 mod p−1 (-4326 to be exact). Had this not been the case, an absurd result would have ensued: We could have shown that 1277x2y≡1 mod p for any ratio x/y of our choosing, by inverting A. So the determinant is bound to be 0 mod p−1.
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