Skip to content

Instantly share code, notes, and snippets.

@NHAS
Forked from shaneutt/LICENSE
Created February 20, 2024 20:23
Show Gist options
  • Save NHAS/874fccca5651eb73506a4033cd848b3d to your computer and use it in GitHub Desktop.
Save NHAS/874fccca5651eb73506a4033cd848b3d to your computer and use it in GitHub Desktop.
Golang: Demonstrate creating a CA Certificate, and Creating and Signing Certs with the CA
package main
import (
"bytes"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"io/ioutil"
"math/big"
"net"
"net/http"
"net/http/httptest"
"strings"
"time"
)
func main() {
// get our ca and server certificate
serverTLSConf, clientTLSConf, err := certsetup()
if err != nil {
panic(err)
}
// set up the httptest.Server using our certificate signed by our CA
server := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "success!")
}))
server.TLS = serverTLSConf
server.StartTLS()
defer server.Close()
// communicate with the server using an http.Client configured to trust our CA
transport := &http.Transport{
TLSClientConfig: clientTLSConf,
}
http := http.Client{
Transport: transport,
}
resp, err := http.Get(server.URL)
if err != nil {
panic(err)
}
// verify the response
respBodyBytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
panic(err)
}
body := strings.TrimSpace(string(respBodyBytes[:]))
if body == "success!" {
fmt.Println(body)
} else {
panic("not successful!")
}
}
func certsetup() (serverTLSConf *tls.Config, clientTLSConf *tls.Config, err error) {
// set up our CA certificate
ca := &x509.Certificate{
SerialNumber: big.NewInt(2019),
Subject: pkix.Name{
Organization: []string{"Company, INC."},
Country: []string{"US"},
Province: []string{""},
Locality: []string{"San Francisco"},
StreetAddress: []string{"Golden Gate Bridge"},
PostalCode: []string{"94016"},
},
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(10, 0, 0),
IsCA: true,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
BasicConstraintsValid: true,
}
// create our private and public key
caPrivKey, err := rsa.GenerateKey(rand.Reader, 4096)
if err != nil {
return nil, nil, err
}
// create the CA
caBytes, err := x509.CreateCertificate(rand.Reader, ca, ca, &caPrivKey.PublicKey, caPrivKey)
if err != nil {
return nil, nil, err
}
// pem encode
caPEM := new(bytes.Buffer)
pem.Encode(caPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: caBytes,
})
caPrivKeyPEM := new(bytes.Buffer)
pem.Encode(caPrivKeyPEM, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(caPrivKey),
})
// set up our server certificate
cert := &x509.Certificate{
SerialNumber: big.NewInt(2019),
Subject: pkix.Name{
Organization: []string{"Company, INC."},
Country: []string{"US"},
Province: []string{""},
Locality: []string{"San Francisco"},
StreetAddress: []string{"Golden Gate Bridge"},
PostalCode: []string{"94016"},
},
IPAddresses: []net.IP{net.IPv4(127, 0, 0, 1), net.IPv6loopback},
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(10, 0, 0),
SubjectKeyId: []byte{1, 2, 3, 4, 6},
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature,
}
certPrivKey, err := rsa.GenerateKey(rand.Reader, 4096)
if err != nil {
return nil, nil, err
}
certBytes, err := x509.CreateCertificate(rand.Reader, cert, ca, &certPrivKey.PublicKey, caPrivKey)
if err != nil {
return nil, nil, err
}
certPEM := new(bytes.Buffer)
pem.Encode(certPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: certBytes,
})
certPrivKeyPEM := new(bytes.Buffer)
pem.Encode(certPrivKeyPEM, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(certPrivKey),
})
serverCert, err := tls.X509KeyPair(certPEM.Bytes(), certPrivKeyPEM.Bytes())
if err != nil {
return nil, nil, err
}
serverTLSConf = &tls.Config{
Certificates: []tls.Certificate{serverCert},
}
certpool := x509.NewCertPool()
certpool.AppendCertsFromPEM(caPEM.Bytes())
clientTLSConf = &tls.Config{
RootCAs: certpool,
}
return
}
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.
In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
For more information, please refer to <https://unlicense.org>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment