add NewZrFromUInt64 to instantiate a new Zr directly from a uint64

driver/amcl/fp256bn.go

@@ -235,7 +235,7 @@ func (b *fp256bnG1) String() string {
 }
 
 func (e *fp256bnG1) Neg() {
-	res := e.Mul(NewFp256bn().NewZrFromInt(-1))
+	res := e.Mul(NewFp256bn().NewZrFromInt64(-1))
 	e.ECP = res.(*fp256bnG1).ECP
 }
 

driver/common/curve.go

@@ -61,10 +61,14 @@ func (c *CurveBase) NewZrFromBytes(b []byte) driver.Zr {
 	return res
 }
 
-func (c *CurveBase) NewZrFromInt(i int64) driver.Zr {
+func (c *CurveBase) NewZrFromInt64(i int64) driver.Zr {
 	return &BaseZr{Int: *big.NewInt(i), Modulus: c.Modulus}
 }
 
+func (c *CurveBase) NewZrFromUint64(i uint64) driver.Zr {
+	return &BaseZr{Int: *new(big.Int).SetUint64(i), Modulus: c.Modulus}
+}
+
 func (c *CurveBase) NewRandomZr(rng io.Reader) driver.Zr {
 	bi, err := rand.Int(rng, &c.Modulus)
 	if err != nil {

driver/math.go

@@ -29,7 +29,8 @@ type Curve interface {
 	NewG1() G1
 	NewG2() G2
 	NewZrFromBytes(b []byte) Zr
-	NewZrFromInt(i int64) Zr
+	NewZrFromInt64(i int64) Zr
+	NewZrFromUint64(i uint64) Zr
 	NewG1FromBytes(b []byte) G1
 	NewG1FromCompressed(b []byte) G1
 	NewG2FromBytes(b []byte) G2

math.go

@@ -480,7 +480,11 @@ func (c *Curve) NewGtFromBytes(b []byte) (p *Gt, err error) {
 }
 
 func (c *Curve) NewZrFromInt(i int64) *Zr {
-	return &Zr{zr: c.c.NewZrFromInt(i), curveID: c.curveID}
+	return &Zr{zr: c.c.NewZrFromInt64(i), curveID: c.curveID}
+}
+
+func (c *Curve) NewZrFromUint64(i uint64) *Zr {
+	return &Zr{zr: c.c.NewZrFromUint64(i), curveID: c.curveID}
 }
 
 func (c *Curve) NewG2() *G2 {

math_test.go

@@ -124,6 +124,11 @@ func runZrTest(t *testing.T, c *Curve) {
 	rng, err := c.Rand()
 	assert.NoError(t, err)
 
+	maxint64 := c.NewZrFromInt(math.MaxInt64)
+	maxuint64 := c.NewZrFromUint64(math.MaxUint64)
+	assert.Equal(t, fmt.Sprintf("%x", math.MaxInt64), maxint64.String())
+	assert.Equal(t, fmt.Sprintf("%x", uint64(math.MaxUint64)), maxuint64.String())
+
 	// serialising and deserialising negative numbers
 	rr := c.NewRandomZr(rng)
 	rr1 := rr.Copy()