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ergo/irc/mkcerts/certs.go
Shivaram Lingamneni f2da69d49f fix #898
2020-03-22 18:18:48 -04:00

103 lines
3.0 KiB
Go

// Copyright (c) 2016 Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license
package mkcerts
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"math/big"
"net"
"os"
"time"
)
// CreateCertBytes creates a testing ECDSA certificate, returning the cert and key bytes.
func CreateCertBytes(orgName string, host string) (certBytes []byte, keyBytes []byte, err error) {
validFrom := time.Now()
validFor := 365 * 24 * time.Hour
notAfter := validFrom.Add(validFor)
priv, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return
}
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return nil, nil, fmt.Errorf("failed to generate serial number: %s", err)
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{orgName},
},
NotBefore: validFrom,
NotAfter: notAfter,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
// TODO: allow explicitly listing allowed addresses/names
template.IPAddresses = append(template.IPAddresses, net.ParseIP("127.0.0.1"))
template.IPAddresses = append(template.IPAddresses, net.ParseIP("::1"))
if host != "" {
template.DNSNames = append(template.DNSNames, host)
}
template.DNSNames = append(template.DNSNames, "localhost")
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
if err != nil {
return nil, nil, fmt.Errorf("Failed to create certificate: %s", err.Error())
}
certBytes = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
b, err := x509.MarshalPKCS8PrivateKey(priv)
if err != nil {
return nil, nil, fmt.Errorf("Unable to marshal private key: %v", err.Error())
}
pemBlock := pem.Block{Type: "PRIVATE KEY", Bytes: b}
keyBytes = pem.EncodeToMemory(&pemBlock)
return certBytes, keyBytes, nil
}
// CreateCert creates a testing ECDSA certificate, outputting the cert and key at the given filenames.
func CreateCert(orgName string, host string, certFilename string, keyFilename string) error {
certBytes, keyBytes, err := CreateCertBytes(orgName, host)
if err != nil {
return err
}
certOut, err := os.Create(certFilename)
if err != nil {
return fmt.Errorf("failed to open %s for writing: %s", certFilename, err.Error())
}
defer certOut.Close()
_, err = certOut.Write(certBytes)
if err != nil {
return fmt.Errorf("failed to write out cert file %s: %s", certFilename, err.Error())
}
keyOut, err := os.OpenFile(keyFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return fmt.Errorf("failed to open %s for writing: %s", keyFilename, err.Error())
}
defer keyOut.Close()
_, err = keyOut.Write(keyBytes)
if err != nil {
return fmt.Errorf("failed to write out key file %s: %s", keyFilename, err.Error())
}
return nil
}