HTTPS（全称：Hyper Text Transfer Protocol over Secure Socket Layer），是以安全为目标的HTTP通道，简单讲是HTTP的安全版。即HTTP下加入SSL层，HTTPS的安全基础是SSL，因此加密的详细内容就需要SSL。 它是一个URI scheme（抽象标识符体系），句法类同http:体系。用于安全的HTTP数据传输。https:URL表明它使用了HTTP，但HTTPS存在不同于HTTP的默认端口及一个加密/身份验证层（在HTTP与TCP之间）。

package main

import (
    "crypto/rand"
    "crypto/rsa"
    "crypto/x509"
    "crypto/x509/pkix"
    "encoding/pem"
    "io/ioutil"
    "math/big"
    "os"
    "time"
)

func main() {
    info := CertInformation{Country: []string{"中国"}, Organization: []string{"游戏蜗牛"},
        OrganizationalUnit: []string{"blog.csdn.net/fyxichen"}, EmailAddress: []string{"czxichen@163.com"},
        StreetAddress: []string{"中心大道西171"}, Province: []string{"江苏省·工业园区"}, SubjectKeyId: []byte{1, 2, 3, 4, 5, 6},
        Certificate: "client.crt", PrivateKey: "client.key", ROOTCertificate: "server.pem", ROOTPrivateKey: "server.key"}
    err := CreateCerts(info)
    if err != nil {
        println(err.Error())
    }
}

type CertInformation struct {
    Country            []string
    Organization       []string
    OrganizationalUnit []string
    EmailAddress       []string
    Province           []string
    StreetAddress      []string
    SubjectKeyId       []byte
    Certificate        string
    PrivateKey         string
    ROOTCertificate    string
    ROOTPrivateKey     string
}

func CreateCerts(info CertInformation) error {

    var rootPrivateKey *rsa.PrivateKey
    var rootcertificate *x509.Certificate
    var err error
    ca := newCertificate(info)
    priv, _ := rsa.GenerateKey(rand.Reader, 2048)

    //读取根证书
    if info.Certificate != "" && info.PrivateKey != "" {
        rootcertificate, rootPrivateKey, err = parseCerts(info.ROOTCertificate, info.ROOTPrivateKey)
        if os.IsNotExist(err) {
            rootPrivateKey, _ = rsa.GenerateKey(rand.Reader, 2048)
            rootcertificate = ca
            ca_b, err := x509.CreateCertificate(rand.Reader, rootcertificate, rootcertificate, &rootPrivateKey.PublicKey, rootPrivateKey)
            if err != nil {
                return err
            }
            err = write(info.ROOTCertificate, "CERTIFICATE", ca_b)
            if err != nil {
                return err
            }
            priv_b := x509.MarshalPKCS1PrivateKey(rootPrivateKey)
            err = write(info.ROOTPrivateKey, "PRIVATE KEY", priv_b)
            if err != nil {
                return err
            }
        } else if err != nil {
            return err
        }
    } else {
        rootcertificate = ca
        rootPrivateKey = priv
    }

    ca_b, err := x509.CreateCertificate(rand.Reader, ca, rootcertificate, &priv.PublicKey, rootPrivateKey)
    if err != nil {
        return err
    }
    err = write(info.Certificate, "CERTIFICATE", ca_b)
    if err != nil {
        return err
    }

    priv_b := x509.MarshalPKCS1PrivateKey(priv)
    err = write(info.PrivateKey, "PRIVATE KEY", priv_b)
    if err != nil {
        return err
    }

    return nil
}

func write(filename, Type string, p []byte) error {
    File, err := os.Create(filename)
    defer File.Close()
    if err != nil {
        return err
    }
    var b *pem.Block = &pem.Block{Bytes: p, Type: Type}
    err = pem.Encode(File, b)
    if err != nil {
        return err
    }
    return nil
}

func parseCerts(ROOTCertificate, ROOTPrivateKey string) (*x509.Certificate, *rsa.PrivateKey, error) {
    var rootPrivateKey *rsa.PrivateKey
    var rootcertificate *x509.Certificate

    buf, err := ioutil.ReadFile(ROOTCertificate)
    if err != nil {
        return nil, nil, err
    }
    p := &pem.Block{}
    p, buf = pem.Decode(buf)
    rootcertificate, err = x509.ParseCertificate(p.Bytes)
    if err != nil {
        return nil, nil, err
    }
    buf, err = ioutil.ReadFile(ROOTPrivateKey)
    if err != nil {
        return nil, nil, err
    }
    p, buf = pem.Decode(buf)
    rootPrivateKey, err = x509.ParsePKCS1PrivateKey(p.Bytes)
    if err != nil {
        return nil, nil, err
    }
    return rootcertificate, rootPrivateKey, nil
}

func newCertificate(info CertInformation) *x509.Certificate {
    return &x509.Certificate{
        SerialNumber: big.NewInt(1653),
        Subject: pkix.Name{
            Country:            info.Country,
            Organization:       info.Organization,
            OrganizationalUnit: info.OrganizationalUnit,
            Province:           info.Province,
            StreetAddress:      info.StreetAddress,
        },
        NotBefore:             time.Now(),
        NotAfter:              time.Now().AddDate(10, 0, 0),
        SubjectKeyId:          info.SubjectKeyId,
        BasicConstraintsValid: true,
        IsCA:           true,
        ExtKeyUsage:    []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
        KeyUsage:       x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
        EmailAddresses: info.EmailAddress,
    }
}