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package libtrust
import (
"crypto/rand"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"io/ioutil"
"math/big"
"net"
"time"
)
type certTemplateInfo struct {
commonName string
domains []string
ipAddresses []net.IP
isCA bool
clientAuth bool
serverAuth bool
}
func generateCertTemplate(info *certTemplateInfo) *x509.Certificate {
// Generate a certificate template which is valid from the past week to
// 10 years from now. The usage of the certificate depends on the
// specified fields in the given certTempInfo object.
var (
keyUsage x509.KeyUsage
extKeyUsage []x509.ExtKeyUsage
)
if info.isCA {
keyUsage = x509.KeyUsageCertSign
}
if info.clientAuth {
extKeyUsage = append(extKeyUsage, x509.ExtKeyUsageClientAuth)
}
if info.serverAuth {
extKeyUsage = append(extKeyUsage, x509.ExtKeyUsageServerAuth)
}
return &x509.Certificate{
SerialNumber: big.NewInt(0),
Subject: pkix.Name{
CommonName: info.commonName,
},
NotBefore: time.Now().Add(-time.Hour * 24 * 7),
NotAfter: time.Now().Add(time.Hour * 24 * 365 * 10),
DNSNames: info.domains,
IPAddresses: info.ipAddresses,
IsCA: info.isCA,
KeyUsage: keyUsage,
ExtKeyUsage: extKeyUsage,
BasicConstraintsValid: info.isCA,
}
}
func generateCert(pub PublicKey, priv PrivateKey, subInfo, issInfo *certTemplateInfo) (cert *x509.Certificate, err error) {
pubCertTemplate := generateCertTemplate(subInfo)
privCertTemplate := generateCertTemplate(issInfo)
certDER, err := x509.CreateCertificate(
rand.Reader, pubCertTemplate, privCertTemplate,
pub.CryptoPublicKey(), priv.CryptoPrivateKey(),
)
if err != nil {
return nil, fmt.Errorf("failed to create certificate: %s", err)
}
cert, err = x509.ParseCertificate(certDER)
if err != nil {
return nil, fmt.Errorf("failed to parse certificate: %s", err)
}
return
}
// GenerateSelfSignedServerCert creates a self-signed certificate for the
// given key which is to be used for TLS servers with the given domains and
// IP addresses.
func GenerateSelfSignedServerCert(key PrivateKey, domains []string, ipAddresses []net.IP) (*x509.Certificate, error) {
info := &certTemplateInfo{
commonName: key.KeyID(),
domains: domains,
ipAddresses: ipAddresses,
serverAuth: true,
}
return generateCert(key.PublicKey(), key, info, info)
}
// GenerateSelfSignedClientCert creates a self-signed certificate for the
// given key which is to be used for TLS clients.
func GenerateSelfSignedClientCert(key PrivateKey) (*x509.Certificate, error) {
info := &certTemplateInfo{
commonName: key.KeyID(),
clientAuth: true,
}
return generateCert(key.PublicKey(), key, info, info)
}
// GenerateCACert creates a certificate which can be used as a trusted
// certificate authority.
func GenerateCACert(signer PrivateKey, trustedKey PublicKey) (*x509.Certificate, error) {
subjectInfo := &certTemplateInfo{
commonName: trustedKey.KeyID(),
isCA: true,
}
issuerInfo := &certTemplateInfo{
commonName: signer.KeyID(),
}
return generateCert(trustedKey, signer, subjectInfo, issuerInfo)
}
// GenerateCACertPool creates a certificate authority pool to be used for a
// TLS configuration. Any self-signed certificates issued by the specified
// trusted keys will be verified during a TLS handshake
func GenerateCACertPool(signer PrivateKey, trustedKeys []PublicKey) (*x509.CertPool, error) {
certPool := x509.NewCertPool()
for _, trustedKey := range trustedKeys {
cert, err := GenerateCACert(signer, trustedKey)
if err != nil {
return nil, fmt.Errorf("failed to generate CA certificate: %s", err)
}
certPool.AddCert(cert)
}
return certPool, nil
}
// LoadCertificateBundle loads certificates from the given file. The file should be pem encoded
// containing one or more certificates. The expected pem type is "CERTIFICATE".
func LoadCertificateBundle(filename string) ([]*x509.Certificate, error) {
b, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
certificates := []*x509.Certificate{}
var block *pem.Block
block, b = pem.Decode(b)
for ; block != nil; block, b = pem.Decode(b) {
if block.Type == "CERTIFICATE" {
cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
return nil, err
}
certificates = append(certificates, cert)
} else {
return nil, fmt.Errorf("invalid pem block type: %s", block.Type)
}
}
return certificates, nil
}
// LoadCertificatePool loads a CA pool from the given file. The file should be pem encoded
// containing one or more certificates. The expected pem type is "CERTIFICATE".
func LoadCertificatePool(filename string) (*x509.CertPool, error) {
certs, err := LoadCertificateBundle(filename)
if err != nil {
return nil, err
}
pool := x509.NewCertPool()
for _, cert := range certs {
pool.AddCert(cert)
}
return pool, nil
}
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