secp256k1: catch curve parameter parse errors

This commit ensures that errors are caught if the format for
specifying the curve parameters ever changes. Before, errors were
silently ignored.

crypto/secp256k1/curve.go

@@ -290,11 +290,11 @@ func init() {
 	// See SEC 2 section 2.7.1
 	// curve parameters taken from:
 	// http://www.secg.org/collateral/sec2_final.pdf
-	theCurve.P, _ = new(big.Int).SetString("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F", 16)
-	theCurve.N, _ = new(big.Int).SetString("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16)
-	theCurve.B, _ = new(big.Int).SetString("0000000000000000000000000000000000000000000000000000000000000007", 16)
-	theCurve.Gx, _ = new(big.Int).SetString("79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798", 16)
-	theCurve.Gy, _ = new(big.Int).SetString("483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8", 16)
+	theCurve.P = math.MustParseBig256("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F")
+	theCurve.N = math.MustParseBig256("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141")
+	theCurve.B = math.MustParseBig256("0x0000000000000000000000000000000000000000000000000000000000000007")
+	theCurve.Gx = math.MustParseBig256("0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798")
+	theCurve.Gy = math.MustParseBig256("0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8")
 	theCurve.BitSize = 256
 }