Search for shards for encode ecdsa private key to PEM format

It hard to describe this issue, maybe show golang code for explain is more clear.

	// MarshalECPrivateKey converts an EC private key to SEC 1, ASN.1 DER form.
	// This kind of key is commonly encoded in PEM blocks of type "EC PRIVATE KEY".
	// For a more flexible key format which is not EC specific, use
	// MarshalPKCS8PrivateKey.
	func MarshalECPrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
		oid, ok := oidFromNamedCurve(key.Curve)
		if !ok {
			return nil, errors.New("x509: unknown elliptic curve")

		return marshalECPrivateKeyWithOID(key, oid)
	// code start from here

	keyData, err := x509.MarshalECPrivateKey(privKey)
	if err != nil {
	buf := &bytes.Buffer{}
	// Encode writes the PEM encoding of pem.Block to buf.
	err = pem.Encode(buf, &pem.Block{
		Type:  "ECDSA Private Key",
		Bytes: keyData,
	return buf

Both of x509.MarshalECPrivateKey and pem.Encode come from go standard library.

the input privKey was generated like this ecdsa.GenerateKey(elliptic.P256(), bytes.NewBuffer(seed)) use standard library too.
the output should be a string like following:

ā€œ-----BEGIN ECDSA Private Key-----\nMHcCAQEEIEnwfSZLjxS1LbO2EszEgtz75i2dhu63Fr0ZRIFzMSB8oAoGCCqGSM49\nAwEHoUQDQgAE3hQPJEBL/7wSqDeuAdSJYYK2U65AqcZl7z/xEk5SYB0DjnnA0b98\n/igatsDrN75hfsnXdGxsASeFnY3uyBq/Bg==\n-----END ECDSA Private Key-----\nā€

I spent hours for search shards works like this on and, but no luck.

Thank you.