Source code for sigma1

'''
**Sigma Protocol 1 (Sigma1)**

*Authors:* Charm Developers

| **Notes:** Sigma protocol for proving knowledge in pairing-based settings

.. rubric:: Scheme Properties

* **Type:** sigma protocol (zero-knowledge proof)
* **Setting:** bilinear groups (pairing-based)
* **Assumption:** DL

.. rubric:: Implementation

:Authors: J. Ayo Akinyele
:Date: 2/2012
'''


from charm.toolbox.sigmaprotocol import Sigma
from charm.toolbox.pairinggroup import ZR,G2,pair


[docs]
class SigmaProtocol1(Sigma):
    def __init__(self, groupObj, common_input=None):
        Sigma.__init__(self, groupObj, common_input)


[docs]
    def prover_state1(self):
        (g, h, H) = Sigma.get(self, ['g', 'h', 'H'])
        r = self.group.random(G2)
        a = pair(g, r)
        Sigma.setState(self, 3)
        return { 'r':r, 'a':a, 'g':g, 'h':h, 'H':H }



[docs]
    def prover_state3(self, input):
        (r, h, c) = Sigma.get(self, ['r','h','c'])
        z = r * (h ** -c)
        Sigma.setState(self, 5)
        return {'z':z }



[docs]
    def prover_state5(self, input):
        Sigma.setState(self, None)
        Sigma.setErrorCode(self, input)
        return None



[docs]
    def verifier_state2(self, input):
        c = self.group.random(ZR)
        Sigma.setState(self, 4)
        return {'c':c }



[docs]
    def verifier_state4(self, input):
        (g, H, a, c, z) = Sigma.get(self, ['g','H','a','c','z'])
        if a == (pair(g,z) * (H ** c)):
            print("SUCCESS!!!!!!!"); result = 'OK'
        else:
            print("Failed!!!"); result = 'FAIL'
        Sigma.setState(self, 6)
        Sigma.setErrorCode(self, result)
        return result



[docs]
    def verifier_state6(self, input):
        Sigma.setState(self, None)
        return None