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Task/Modular-exponentiation/Visual-Basic-.NET/modular-exponentiation.vb

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+' Modular exponentiation - VB.Net - 21/01/2019
+    Imports System.Numerics
+
+    Private Sub Main()
+        Dim a, b, m, x As BigInteger
+        a = BigInteger.Parse("2988348162058574136915891421498819466320163312926952423791023078876139")
+        b = BigInteger.Parse("2351399303373464486466122544523690094744975233415544072992656881240319")
+        m = BigInteger.Pow(10, 40)   '=10^40
+        x = ModPowBig(a, b, m)
+        Debug.Print("x=" & x.ToString)
+    End Sub 'Main
+
+    Function ModPowBig(ByVal base As BigInteger, ByVal exponent As BigInteger, ByVal modulus As BigInteger) As BigInteger
+        Dim result As BigInteger
+        result = 1
+        Do While exponent > 0
+            If (exponent Mod 2) = 1 Then
+                result = (result * base) Mod modulus
+            End If
+            exponent = exponent / 2
+            base = (base * base) Mod modulus
+        Loop
+        Return result
+    End Function 'ModPowBig