ofdReader, err :=NewOFDReader(testpath, WithValidator(XXValidator{}))
if err != nil {
	t.Logf("%s", err)
}
defer ofdReader.Close()

package ofd

import (
	"crypto/ecdsa"
	std "encoding/asn1"
	"math/big"

	"github.com/emmansun/gmsm/sm2"
	"github.com/emmansun/gmsm/sm3"
	"github.com/emmansun/gmsm/smx509"
)

type OtherValidator struct {
}


func (gm *OtherValidator) Digest(msg []byte) []byte {
	h := sm3.New()
	h.Write(msg)
	dataDash := h.Sum(nil)
	return dataDash

}
func (gm *OtherValidator) Verify(cert []byte, msg []byte, signature []byte) (bool, error) {
	certificate, err := smx509.ParseCertificate(cert)
	if err != nil {
		return false, err
	}
	pk := certificate.PublicKey.(*ecdsa.PublicKey)
	if len(signature) == 64 {
		r := new(big.Int).SetBytes(signature[0:32])
		s := new(big.Int).SetBytes(signature[32:64])

		result := sm2.VerifyWithSM2(pk, nil, msg, r, s)
		return result, nil
	} else {
		type Sign struct {
			R *big.Int
			S *big.Int
		}
		var sign Sign
		if _, err := std.Unmarshal(signature, &sign); err != nil {
			return false, err
		} else {
			ff, _ := new(big.Int).SetString(MAX, 16)
			if sign.R.Sign() == -1 {
				sign.R.And(sign.R, ff)
			}
			if sign.S.Sign() == -1 {
				sign.S.And(sign.S, ff)
			}
			result := sm2.VerifyWithSM2(pk, nil, msg, sign.R, sign.S)
			return result, nil
		}
	}
}