The prime q.
The prime q is the base field size of the curve E_{BLS}.
q is computed from the parameter x: q = (x - 1)^{2}r/3 + x where r = x^4 - x^2 + 1 .
Figure 16 of the Zexe paper lists its value in hexadecimal:
0x1ae3a4617c510eac63b05c06ca1493b1a22d9f300f5138f1ef3622fba094800170b5d44300000008508c00000000001
