remove the use of math.Pow

Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

Author: adecaro

token/core/zkatdlog/crypto/rp/bulletproof_test.go

@@ -7,7 +7,6 @@ SPDX-License-Identifier: Apache-2.0
 package rp_test
 
 import (
-	math2 "math"
 	"strconv"
 
 	math "github.com/IBM/mathlib"
@@ -23,7 +22,7 @@ var _ = Describe("Range Proof", func() {
 			It("Succeeds", func() {
 				curve := math.Curves[1]
 				nr := uint64(3)
-				l := uint64(math2.Pow(2, float64(nr)))
+				l := uint64(1 << nr)
 				leftGens := make([]*math.G1, l)
 				rightGens := make([]*math.G1, l)
 

token/core/zkatdlog/crypto/rp/ipa_test.go

@@ -6,7 +6,6 @@ SPDX-License-Identifier: Apache-2.0
 package rp_test
 
 import (
-	math2 "math"
 	"strconv"
 
 	math "github.com/IBM/mathlib"
@@ -22,7 +21,7 @@ var _ = Describe("Inner Product Argument", func() {
 			It("Succeeds", func() {
 				curve := math.Curves[0]
 				nr := uint64(6)
-				l := uint64(math2.Pow(2, float64(nr)))
+				l := uint64(1 << nr)
 				leftGens := make([]*math.G1, l)
 				rightGens := make([]*math.G1, l)
 				left := make([]*math.Zr, l)

token/core/zkatdlog/crypto/setup.go

@@ -39,8 +39,11 @@ func (rpp *RangeProofParams) Validate() error {
 	if rpp.NumberOfRounds == 0 {
 		return errors.New("invalid range proof parameters: number of rounds is zero")
 	}
-	if rpp.BitLength != uint64(math.Pow(2, float64(rpp.NumberOfRounds))) {
-		return errors.Errorf("invalid range proof parameters: bit length should be %d\n", int(math.Pow(2, float64(rpp.NumberOfRounds))))
+	if rpp.NumberOfRounds > 64 {
+		return errors.New("invalid range proof parameters: number of rounds must be smaller or equal to 64")
+	}
+	if rpp.BitLength != uint64(1<<rpp.NumberOfRounds) {
+		return errors.Errorf("invalid range proof parameters: bit length should be %d\n", uint64(1<<rpp.NumberOfRounds))
 	}
 	if len(rpp.LeftGenerators) != len(rpp.RightGenerators) {
 		return errors.Errorf("invalid range proof parameters: the size of the left generators does not match the size of the right generators [%d vs, %d]", len(rpp.LeftGenerators), len(rpp.RightGenerators))