implemented VerifySort and new testcases and codecleanup

Utility.py

@@ -24,14 +24,10 @@ def genratePublicPrivateKey():
 
     pass
 
-def VRF(sk,seed,rolecount,w,badaW,pk):
+def VRF(sk,seed,pk):
     '''
-
     :param sk: secrete key
     :param seed:
-    :param rolecount:
-    :param w: users stake or weight
-    :param badaW: total stake in game i.e. sum of wi
     :param pk:  public key of user
     :return: (bytes array of signature may not b of fixed length | public key as a proof)
     '''
@@ -51,20 +47,21 @@ def verifyVRF(pk,hash,proof,seed):
     return True
 
 
-def sortition(sk,seed,rolecount,w,badaW,pk):
+def sortition(sk,seed,rolecount,role,w,badaW,pk):
     '''
     :param sk: secrete key
     :param seed:
-    :param rolecount:
+    :param rolecount: tou
+    :param role:
     :param w: users stake or weight
     :param badaW: total stake in game i.e. sum of wi
     :param pk:  public key of user
     :return: (bytes array of signature may not b of fixed length | public key as a proof)
     '''
 
-    newseed = (seed,rolecount)
-    hash,proof = VRF(sk, newseed, 3, w, badaW, pk)
-    p = w/badaW
+    newseed = (seed,role)
+    hash,proof = VRF(sk, newseed, pk)
+    p = rolecount/badaW
     j=0
 
     #simplifying the computation : hash/(2**hashlen)
@@ -91,6 +88,51 @@ def sortition(sk,seed,rolecount,w,badaW,pk):
 
     return (hash,proof,j)
 
+
+def verifySort(pk,hash,proof,seed,rolecount,role,w,badaW):
+    '''
+    :param pk: public key of user
+    :param hash:
+    :param proof:
+    :param seed:
+    :param rolecount: tou
+    :param role:
+    :param w: users stake or weight
+    :param badaW: total stake in game i.e. sum of wi
+    :return: number of selected users in commity for the user with pk
+    '''
+
+    newseed = (seed,role)
+    if not verifyVRF(pk,hash,proof,newseed):
+        return 0;
+
+    p = rolecount/badaW
+    j=0
+
+    #simplifying the computation : hash/(2**hashlen)
+    tempHash = bytes_to_int(hash[:32])  # converting first 32 bytes to integer i.e 32*8 bits ie 256 bits
+    x = tempHash / (2 ** 256)
+
+    # print(x)
+
+    lastValue = 0;
+    # print("probability : ",p)
+
+
+    flag = True
+    while(flag):
+        lastValue = lastValue + stats.binom.pmf(j, w, p)
+        nextvalue = lastValue + stats.binom.pmf(j + 1, w, p)
+        # print(lastValue,nextvalue)
+        if (((lastValue<=x) and (nextvalue>x))):
+            break
+        if j == w+1:
+            j=0
+            break
+        j = j+1
+
+    return j
+
 def computeRange():
     badaW=10
     lastValue = 0;
@@ -125,7 +167,7 @@ def testingBinom():
 def testHashlen():
     keypair = genratePublicPrivateKey()
     seed = ("a", 1, 2)
-    x = VRF(keypair[0], seed, 3, 5, 30, keypair[1])
+    x = VRF(keypair[0], seed,  keypair[1])
     print(len(binascii.hexlify(x[0])))
     print(len(x[0]))
     temp = bytes_to_int(x[0][:32])  # converting first 32 bytes to integer i.e 32*8 bits ie 256 bits
@@ -135,25 +177,62 @@ def testHashlen():
 def testSortition():
     sk,pk = genratePublicPrivateKey()
     seed = ("a",1,2)
-    rolecount = 1
+    roleCount = 26
+    role = "LEAD"
+    w = 20
+    badaW = 100
+    hash,proof,j = sortition(sk,seed,roleCount,role,w,badaW,pk)
+    # print(hash) #this is a real content of hash it should be used as final thing and not hexlify
+    print(binascii.hexlify(hash))
+    print(proof)
+    print(j)
+
+def testVerifySort():
+    sk, pk = genratePublicPrivateKey()
+    seed = ("a", 1, 2)
+    roleCount = 26
+    role = "LEAD"
     w = 20
     badaW = 100
-    hash,proof,j = sortition(sk,seed,rolecount,w,badaW,pk)
+    hash, proof, j = sortition(sk, seed, roleCount, role, w, badaW, pk)
     # print(hash) #this is a real content of hash it should be used as final thing and not hexlify
+    print("-----sortition output -----------")
     print(binascii.hexlify(hash))
     print(proof)
     print(j)
+    print("----------------------------------")
+
+    seed2 = ("a", 1, 2)
+    roleCount2 = 26
+    role2 = "LEAD"
+    w2 = 20
+    badaW = 100
+    y = verifySort(pk,hash,proof, seed2, roleCount2, role2, w2, badaW)
+    print(y)
+    assert (j==y),"Test VerifySort failed : "
+
+
+    seed3 = ("a", 1, 2)
+    roleCount3 = 26
+    role3 = "Commitee"
+    w3 = 20
+    badaW = 100
+    y = verifySort(pk,hash,proof, seed3, roleCount3, role3, w3, badaW)
+    print(y)
+    assert (y==0),"Test Verify sort failed : change of seed not detected"
+
 
 def testVerifyVRF():
     sk,pk = genratePublicPrivateKey()
     seed = ("a",1,2)
-    hash,proof= VRF(sk,seed,3,2,30,pk)
+    hash,proof= VRF(sk,seed,pk)
     seed2 = ("a", 1, 2)
     status = verifyVRF(pk,hash,proof,seed2)
     print(status)
 
 
 if __name__ == '__main__':
-    testSortition()
+    # testSortition()
     # testVerifyVRF()
+    testVerifySort()