在golang中crypto.subtle.exportKey的替代方案是什么

package main

import (
    "crypto/rand"
    "crypto/rsa"
    "crypto/x509"
    "encoding/pem"
    "fmt"
    "os"
)

func main() {
    // 生成RSA私钥
    privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
    if err != nil {
        fmt.Println("Failed to generate private key:", err)
        return
    }

    // 将私钥编码为PKCS#8格式的DER编码字节切片
    privateKeyBytes, err := x509.MarshalPKCS8PrivateKey(privateKey)
    if err != nil {
        fmt.Println("Failed to marshal private key:", err)
        return
    }

    // 将私钥字节切片写入文件
    file, err := os.Create("private_key.pem")
    if err != nil {
        fmt.Println("Failed to create file:", err)
        return
    }
    defer file.Close()

    pemBlock := &pem.Block{
        Type:  "PRIVATE KEY",
        Bytes: privateKeyBytes,
    }

    err = pem.Encode(file, pemBlock)
    if err != nil {
        fmt.Println("Failed to write private key to file:", err)
        return
    }

    fmt.Println("Private key exported successfully.")
}