func ParseECPrivateKey(der []byte) (*ecdsa.PrivateKey, error) {
	return parseECPrivateKey(nil, der)
}
ParseECPrivateKey parses an EC private key in SEC 1, ASN.1 DER form.

This kind of key is commonly encoded in PEM blocks of type "EC PRIVATE KEY".
package x509
import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"errors"
	"fmt"
	"math/big"
	"github.com/google/certificate-transparency-go/asn1"
)
const ecPrivKeyVersion = 1
type ecPrivateKey struct {
	Version       int
	PrivateKey    []byte
	NamedCurveOID asn1.ObjectIdentifier `asn1:"optional,explicit,tag:0"`
	PublicKey     asn1.BitString        `asn1:"optional,explicit,tag:1"`
}