RSA 공용 키 파일 생성 코드 구현

package main

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

func main() {
    var bits int
    flag.IntVar(&bits, "b", 1024, " ， 1024")
    flag.Parse()

    if GenRsaKey(bits) != nil {
        log.Fatalln(" ！")
    }
    log.Println(" ！")
}

func GenRsaKey(bits int) error {
    //  
    privateKey, err := rsa.GenerateKey(rand.Reader, bits)
    if err != nil {
        return nil
    }
    derStream := x509.MarshalPKCS1PrivateKey(privateKey)
    /*   */
    block := &pem.Block{
        Type:"PRIVATE KEY",
        Bytes:derStream,
    }
    fi, err := os.Create("private.pem")
    if err != nil {
        return err
    }
    err = pem.Encode(fi, block)
    if err != nil {
        return err
    }
    /*   */
    //  
    publicKey := &privateKey.PublicKey
    derPkix, err := x509.MarshalPKIXPublicKey(publicKey)
    if err != nil {
        return err
    }
    /*   */
    block = &pem.Block{
        Type:"PUBLIC KEY",
        Bytes:derPkix,
    }
    fi, err = os.Create("public.pem")
    if err != nil {
        return err
    }
    err = pem.Encode(fi, block)
    /*   */
    return err
}

package main

import (
    "io/ioutil"
    "log"
    "github.com/syndtr/goleveldb/leveldb/errors"
    "encoding/pem"
    "crypto/x509"
    "crypto/rsa"
    "fmt"
)

//  
var privateKey, publicKey []byte

func init() {
    var err error
    publicKey, err = ioutil.ReadFile("public.pem")
    if err != nil {
        log.Fatalln(err)
    }
    privateKey, err = ioutil.ReadFile("private.pem")
    if err != nil {
        log.Fatalln(err)
    }
}
/**
 *  ： RSA 
 *  ：public
 *  ：  RSA  ，  error  
 */
func GetPubKeyLen(pubKey []byte) (int, error) {
    if pubKey == nil {
        return 0, errors.New("input arguments error")
    }
    block, _ := pem.Decode(publicKey)
    if block == nil {
        return 0, errors.New("public rsaKey error")
    }
    pubInterface, err := x509.ParsePKIXPublicKey(block.Bytes)
    if err != nil {
        return 0, err
    }
    pub := pubInterface.(*rsa.PublicKey)
    return pub.N.BitLen(), nil
}
/*
     RSA 
    PriKey
      RSA  ， error
 */
func GetPriKeyLen(priKey []byte) (int, error) {
    if priKey == nil {
        return 0, errors.New("input arguments error")
    }
    block, _ := pem.Decode(priKey)
    if block == nil {
        return 0, errors.New("private rsaKey error")
    }
    priv, err := x509.ParsePKCS1PrivateKey(block.Bytes)
    if err != nil {
        return 0, err
    }
    return priv.N.BitLen(), nil
}

func main() {
    //  rsa  
    pubKeyLen, _ := GetPubKeyLen(publicKey)
    fmt.Println(pubKeyLen)

    //  rsa  
    privateLen, _ := GetPriKeyLen(privateKey)
    fmt.Println(privateLen)
}