SHA256WithRSA签名算法(golang实现)

func Sha256WithRsa(privateRaw string, msg string) (string, error) {
	privateRaw = strings.Trim(privateRaw, "\n")
	if !strings.HasPrefix(privateRaw, "-----BEGIN RSA PRIVATE KEY-----") {
		privateRaw = fmt.Sprintf("%s\n%s\n%s", "-----BEGIN RSA PRIVATE KEY-----", privateRaw, "-----END RSA PRIVATE KEY-----")
	}

	blockPri, _ := pem.Decode([]byte(privateRaw))
	if blockPri == nil {
		return "", fmt.Errorf("blockPri is nil")
	}

	rsaPri, e := genPriKey(blockPri.Bytes, PKCS8)
	if e != nil {
		panic(e)
	}

	h := sha256.New()
	h.Write([]byte(msg))
	d := h.Sum(nil)

	signature, err := rsa.SignPKCS1v15(rand.Reader, rsaPri, crypto.SHA256, d)
	if err != nil {
		return "", errorx.Wrap(err)
	}
	encodedSig := base64.StdEncoding.EncodeToString(signature)
	return encodedSig, nil
}

const (
	PKCS1 int64 = iota
	PKCS8
)

func genPriKey(privateKey []byt