Move handlers into separate package

handlers/index.go

@@ -0,0 +1,98 @@
+package handlers
+
+import (
+	"html/template"
+	"net/http"
+
+	"github.com/gorilla/csrf"
+	"github.com/nicksnyder/go-i18n/v2/i18n"
+	log "github.com/sirupsen/logrus"
+)
+
+type IndexHandler struct {
+	bundle *i18n.Bundle
+}
+
+func NewIndexHandler(bundle *i18n.Bundle) *IndexHandler {
+	return &IndexHandler{bundle: bundle}
+}
+
+func (i *IndexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	localizer := i18n.NewLocalizer(i.bundle, r.Header.Get("Accept-Language"))
+	csrGenTitle := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "CSRGenTitle",
+		Other: "CSR generation in browser",
+	}})
+	nameLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "NameLabel",
+		Other: "Your name",
+	}})
+	nameHelpText := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "NameHelpText",
+		Other: "Please input your name as it should be added to your certificate",
+	}})
+	passwordLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "PasswordLabel",
+		Other: "Password for your client certificate",
+	}})
+	rsaKeySizeLegend := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "RSAKeySizeLabel",
+		Other: "RSA Key Size",
+	}})
+	rsa3072Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "RSA3072Label",
+		Other: "3072 Bit",
+	}})
+	rsa2048Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "RSA2048Label",
+		Other: "2048 Bit (not recommended)",
+	}})
+	rsa4096Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "RSA4096Label",
+		Other: "4096 Bit",
+	}})
+	rsaHelpText := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID: "RSAHelpText",
+		Other: "An RSA key pair will be generated in your browser. Longer key" +
+			" sizes provide better security but take longer to generate.",
+	}})
+	csrButtonLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "CSRButtonLabel",
+		Other: "Generate signing request",
+	}})
+	statusLoading := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "StatusLoading",
+		Other: "Loading ...",
+	}})
+	downloadLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "DownloadLabel",
+		Other: "Download",
+	}})
+	downloadDescription := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID: "DownloadDescription",
+		Other: "Your key material is ready for download. The downloadable file contains your private key and your" +
+			" certificate encrypted with your password. You can now use the file to install your certificate in your" +
+			" browser or other applications.",
+	}})
+
+	t := template.Must(template.ParseFiles("templates/index.html"))
+	err := t.Execute(w, map[string]interface{}{
+		"Title":               csrGenTitle,
+		"NameLabel":           nameLabel,
+		"NameHelpText":        nameHelpText,
+		"PasswordLabel":       passwordLabel,
+		"RSAKeySizeLegend":    rsaKeySizeLegend,
+		"RSA3072Label":        rsa3072Label,
+		"RSA2048Label":        rsa2048Label,
+		"RSA4096Label":        rsa4096Label,
+		"RSAHelpText":         rsaHelpText,
+		"CSRButtonLabel":      csrButtonLabel,
+		"StatusLoading":       statusLoading,
+		"DownloadDescription": downloadDescription,
+		"DownloadLabel":       downloadLabel,
+		csrf.TemplateTag:      csrf.TemplateField(r),
+	})
+	if err != nil {
+		log.Panic(err)
+	}
+}

handlers/jslocales.go

@@ -0,0 +1,55 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"github.com/nicksnyder/go-i18n/v2/i18n"
+)
+
+type JSLocalesHandler struct {
+	bundle *i18n.Bundle
+}
+
+func NewJSLocalesHandler(bundle *i18n.Bundle) *JSLocalesHandler {
+	return &JSLocalesHandler{bundle: bundle}
+}
+
+func (j *JSLocalesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	parts := strings.Split(r.URL.Path, "/")
+	if len(parts) != 4 {
+		http.Error(w, "Not found", http.StatusNotFound)
+		return
+	}
+	lang := parts[2]
+
+	localizer := i18n.NewLocalizer(j.bundle, lang)
+
+	type translationData struct {
+		Keygen struct {
+			Started   string `json:"started"`
+			Running   string `json:"running"`
+			Generated string `json:"generated"`
+		} `json:"keygen"`
+	}
+
+	translations := &translationData{}
+	translations.Keygen.Started = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "JavaScript.KeyGen.Started",
+		Other: "started key generation",
+	}})
+	translations.Keygen.Running = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "JavaScript.KeyGen.Running",
+		Other: "key generation running for __seconds__ seconds",
+	}})
+	translations.Keygen.Generated = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
+		ID:    "JavaScript.KeyGen.Generated",
+		Other: "key generated in __seconds__ seconds",
+	}})
+
+	encoder := json.NewEncoder(w)
+	if err := encoder.Encode(translations); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+}

handlers/signing.go

@@ -0,0 +1,171 @@
+package handlers
+
+import (
+	"bytes"
+	"crypto/x509"
+	"encoding/json"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"os/exec"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type CertificateSigningHandler struct {
+	caCertificates []*x509.Certificate
+	caChainMap     map[string][]string
+}
+
+func NewCertificateSigningHandler(caCertificates []*x509.Certificate) *CertificateSigningHandler {
+	return &CertificateSigningHandler{caCertificates: caCertificates, caChainMap: make(map[string][]string)}
+}
+
+func (h *CertificateSigningHandler) sign(csrPem string, commonName string) (certPem string, caChain []string, err error) {
+	log.Printf("received CSR for %s:\n\n%s", commonName, csrPem)
+	subjectDN := fmt.Sprintf("/CN=%s", commonName)
+	var csrFile *os.File
+	if csrFile, err = ioutil.TempFile("", "*.csr.pem"); err != nil {
+		log.Errorf("could not open temporary file: %s", err)
+		return
+	}
+	if _, err = csrFile.Write([]byte(csrPem)); err != nil {
+		log.Errorf("could not write CSR to file: %s", err)
+		return
+	}
+	if err = csrFile.Close(); err != nil {
+		log.Errorf("could not close CSR file: %s", err)
+		return
+	}
+	defer func(file *os.File) {
+		err = os.Remove(file.Name())
+		if err != nil {
+			log.Errorf("could not remove temporary file: %s", err)
+		}
+	}(csrFile)
+
+	opensslCommand := exec.Command(
+		"openssl", "ca", "-config", "ca.cnf",
+		"-policy", "policy_match", "-extensions", "client_ext",
+		"-batch", "-subj", subjectDN, "-utf8", "-rand_serial", "-in", "in.pem")
+	var out, cmdErr bytes.Buffer
+	opensslCommand.Stdout = &out
+	opensslCommand.Stderr = &cmdErr
+	err = opensslCommand.Run()
+	if err != nil {
+		log.Print(err)
+		log.Print(cmdErr.String())
+		return
+	}
+
+	var block *pem.Block
+	if block, _ = pem.Decode(out.Bytes()); block == nil {
+		err = fmt.Errorf("could not decode pem")
+		return
+	}
+	var certificate *x509.Certificate
+	if certificate, err = x509.ParseCertificate(block.Bytes); err != nil {
+		return
+	}
+
+	certPem = string(pem.EncodeToMemory(&pem.Block{
+		Type:  "CERTIFICATE",
+		Bytes: certificate.Raw,
+	}))
+
+	caChain, err = h.getCAChain(certificate)
+	return
+}
+
+func (h *CertificateSigningHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != "POST" {
+		http.Error(w, "Only POST requests support", http.StatusMethodNotAllowed)
+		return
+	}
+	if r.Header.Get("content-type") != "application/json" {
+		http.Error(w, "Only JSON content is accepted", http.StatusNotAcceptable)
+		return
+	}
+	var err error
+	var requestBody requestData
+	var responseData responseData
+
+	if err = json.NewDecoder(r.Body).Decode(&requestBody); err != nil {
+		log.Print(err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	responseData.Certificate, responseData.CAChain, err = h.sign(requestBody.Csr, requestBody.CommonName)
+	if err != nil {
+		http.Error(w, "Could not sign certificate", http.StatusInternalServerError)
+		return
+	}
+
+	var jsonBytes []byte
+	if jsonBytes, err = json.Marshal(&responseData); err != nil {
+		log.Print(err)
+	}
+
+	if _, err = w.Write(jsonBytes); err != nil {
+		log.Print(err)
+	}
+}
+
+type requestData struct {
+	Csr        string `json:"csr"`
+	CommonName string `json:"commonName"`
+}
+
+type responseData struct {
+	Certificate string   `json:"certificate"`
+	CAChain     []string `json:"ca_chain"`
+}
+
+func (h *CertificateSigningHandler) getCAChain(certificate *x509.Certificate) ([]string, error) {
+	issuerString := string(certificate.RawIssuer)
+
+	if value, exists := h.caChainMap[issuerString]; exists {
+		return value, nil
+	}
+
+	result := make([]string, 0)
+
+	appendCert := func(cert *x509.Certificate) {
+		result = append(
+			result,
+			string(pem.EncodeToMemory(&pem.Block{Bytes: cert.Raw, Type: "CERTIFICATE"})))
+		log.Debugf("added %s to cachain", result[len(result)-1])
+	}
+
+	var previous *x509.Certificate
+	var count = 0
+	for {
+		if len(h.caCertificates) == 0 {
+			return nil, errors.New("no CA certificates loaded")
+		}
+		if count > len(h.caCertificates) {
+			return nil, errors.New("could not construct certificate chain")
+		}
+		for _, caCert := range h.caCertificates {
+			if previous == nil {
+				if bytes.Equal(caCert.RawSubject, certificate.RawIssuer) {
+					previous = caCert
+					appendCert(caCert)
+				}
+			} else if bytes.Equal(previous.RawSubject, previous.RawIssuer) {
+				h.caChainMap[issuerString] = result
+				return result, nil
+			} else if bytes.Equal(caCert.RawSubject, previous.RawIssuer) {
+				previous = caCert
+				appendCert(caCert)
+			} else {
+				log.Debugf("skipped certificate %s", caCert.Subject)
+			}
+		}
+		count++
+	}
+}

main.go

@@ -1,19 +1,15 @@
 package main
 
 import (
-	"bytes"
 	"crypto/rand"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/base64"
-	"encoding/json"
 	"encoding/pem"
 	"fmt"
-	"html/template"
 	"io/ioutil"
 	"net/http"
 	"os"
-	"os/exec"
 	"os/signal"
 	"strings"
 	"syscall"
@@ -24,346 +20,33 @@ import (
 	"github.com/nicksnyder/go-i18n/v2/i18n"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/text/language"
+
+	"git.dittberner.info/jan/browser_csr_generation/handlers"
 )
 
-type signCertificate struct{}
-
-type requestData struct {
-	Csr        string `json:"csr"`
-	CommonName string `json:"commonName"`
-}
-
-type responseData struct {
-	Certificate string   `json:"certificate"`
-	CAChain     []string `json:"ca_chain"`
-}
-
-var caCertificates []*x509.Certificate
-
-func (h *signCertificate) sign(csrPem string, commonName string) (certPem string, caChain []string, err error) {
-	log.Printf("received CSR for %s:\n\n%s", commonName, csrPem)
-	subjectDN := fmt.Sprintf("/CN=%s", commonName)
-	var csrFile *os.File
-	if csrFile, err = ioutil.TempFile("", "*.csr.pem"); err != nil {
-		log.Errorf("could not open temporary file: %s", err)
-		return
-	}
-	if _, err = csrFile.Write([]byte(csrPem)); err != nil {
-		log.Errorf("could not write CSR to file: %s", err)
-		return
-	}
-	if err = csrFile.Close(); err != nil {
-		log.Errorf("could not close CSR file: %s", err)
-		return
-	}
-	defer func(file *os.File) {
-		err = os.Remove(file.Name())
-		if err != nil {
-			log.Errorf("could not remove temporary file: %s", err)
-		}
-	}(csrFile)
-
-	opensslCommand := exec.Command(
-		"openssl", "ca", "-config", "ca.cnf",
-		"-policy", "policy_match", "-extensions", "client_ext",
-		"-batch", "-subj", subjectDN, "-utf8", "-rand_serial", "-in", "in.pem")
-	var out, cmdErr bytes.Buffer
-	opensslCommand.Stdout = &out
-	opensslCommand.Stderr = &cmdErr
-	err = opensslCommand.Run()
-	if err != nil {
-		log.Print(err)
-		log.Print(cmdErr.String())
-		return
-	}
-
-	var block *pem.Block
-	if block, _ = pem.Decode(out.Bytes()); block == nil {
-		err = fmt.Errorf("could not decode pem")
-		return
-	}
-	var certificate *x509.Certificate
-	if certificate, err = x509.ParseCertificate(block.Bytes); err != nil {
-		return
-	}
-
-	certPem = string(pem.EncodeToMemory(&pem.Block{
-		Type:  "CERTIFICATE",
-		Bytes: certificate.Raw,
-	}))
-
-	caChain, err = h.getCAChain(certificate)
-	return
-}
-
-func (h *signCertificate) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if r.Method != "POST" {
-		http.Error(w, "Only POST requests support", http.StatusMethodNotAllowed)
-		return
-	}
-	if r.Header.Get("content-type") != "application/json" {
-		http.Error(w, "Only JSON content is accepted", http.StatusNotAcceptable)
-		return
-	}
-	var err error
-	var requestBody requestData
-
-	var responseData responseData
-
-	if err = json.NewDecoder(r.Body).Decode(&requestBody); err != nil {
-		log.Print(err)
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
-	}
-
-	responseData.Certificate, responseData.CAChain, err = h.sign(requestBody.Csr, requestBody.CommonName)
-	if err != nil {
-		http.Error(w, "Could not sign certificate", http.StatusInternalServerError)
-		return
-	}
-
-	var jsonBytes []byte
-	if jsonBytes, err = json.Marshal(&responseData); err != nil {
-		log.Print(err)
-	}
-
-	if _, err = w.Write(jsonBytes); err != nil {
-		log.Print(err)
-	}
-}
-
-func (*signCertificate) getCAChain(certificate *x509.Certificate) ([]string, error) {
-	result := make([]string, 0)
-
-	appendCert := func(cert *x509.Certificate) {
-		result = append(
-			result,
-			string(pem.EncodeToMemory(&pem.Block{Bytes: cert.Raw, Type: "CERTIFICATE"})))
-		log.Debugf("added %s to cachain", result[len(result)-1])
-	}
-
-	var previous *x509.Certificate
-	for {
-		if len(caCertificates) == 0 {
-			return result, nil
-		}
-		for _, caCert := range caCertificates {
-			if previous == nil {
-				if bytes.Equal(caCert.RawSubject, certificate.RawIssuer) {
-					previous = caCert
-					appendCert(caCert)
-				}
-			} else if bytes.Equal(previous.RawSubject, previous.RawIssuer) {
-				return result, nil
-			} else if bytes.Equal(caCert.RawSubject, previous.RawIssuer) {
-				previous = caCert
-				appendCert(caCert)
-			} else {
-				log.Debugf("skipped certificate %s", caCert.Subject)
-			}
-		}
-	}
-}
-
-type indexHandler struct {
-	Bundle *i18n.Bundle
-}
-
-func (i *indexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	localizer := i18n.NewLocalizer(i.Bundle, r.Header.Get("Accept-Language"))
-	csrGenTitle := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "CSRGenTitle",
-		Other: "CSR generation in browser",
-	}})
-	nameLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "NameLabel",
-		Other: "Your name",
-	}})
-	nameHelpText := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "NameHelpText",
-		Other: "Please input your name as it should be added to your certificate",
-	}})
-	passwordLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "PasswordLabel",
-		Other: "Password for your client certificate",
-	}})
-	rsaKeySizeLegend := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "RSAKeySizeLabel",
-		Other: "RSA Key Size",
-	}})
-	rsa3072Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "RSA3072Label",
-		Other: "3072 Bit",
-	}})
-	rsa2048Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "RSA2048Label",
-		Other: "2048 Bit (not recommended)",
-	}})
-	rsa4096Label := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "RSA4096Label",
-		Other: "4096 Bit",
-	}})
-	rsaHelpText := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID: "RSAHelpText",
-		Other: "An RSA key pair will be generated in your browser. Longer key" +
-			" sizes provide better security but take longer to generate.",
-	}})
-	csrButtonLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "CSRButtonLabel",
-		Other: "Generate signing request",
-	}})
-	statusLoading := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "StatusLoading",
-		Other: "Loading ...",
-	}})
-	downloadLabel := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "DownloadLabel",
-		Other: "Download",
-	}})
-	downloadDescription := localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID: "DownloadDescription",
-		Other: "Your key material is ready for download. The downloadable file contains your private key and your" +
-			" certificate encrypted with your password. You can now use the file to install your certificate in your" +
-			" browser or other applications.",
-	}})
-
-	t := template.Must(template.ParseFiles("templates/index.html"))
-	err := t.Execute(w, map[string]interface{}{
-		"Title":               csrGenTitle,
-		"NameLabel":           nameLabel,
-		"NameHelpText":        nameHelpText,
-		"PasswordLabel":       passwordLabel,
-		"RSAKeySizeLegend":    rsaKeySizeLegend,
-		"RSA3072Label":        rsa3072Label,
-		"RSA2048Label":        rsa2048Label,
-		"RSA4096Label":        rsa4096Label,
-		"RSAHelpText":         rsaHelpText,
-		"CSRButtonLabel":      csrButtonLabel,
-		"StatusLoading":       statusLoading,
-		"DownloadDescription": downloadDescription,
-		"DownloadLabel":       downloadLabel,
-		csrf.TemplateTag:      csrf.TemplateField(r),
-	})
-	if err != nil {
-		log.Panic(err)
-	}
-}
-
-type jsLocalesHandler struct {
-	Bundle *i18n.Bundle
-}
-
-func (j *jsLocalesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	parts := strings.Split(r.URL.Path, "/")
-	if len(parts) != 4 {
-		http.Error(w, "Not found", http.StatusNotFound)
-		return
-	}
-	lang := parts[2]
-
-	localizer := i18n.NewLocalizer(j.Bundle, lang)
-
-	type translationData struct {
-		Keygen struct {
-			Started   string `json:"started"`
-			Running   string `json:"running"`
-			Generated string `json:"generated"`
-		} `json:"keygen"`
-	}
-
-	translations := &translationData{}
-	translations.Keygen.Started = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "JavaScript.KeyGen.Started",
-		Other: "started key generation",
-	}})
-	translations.Keygen.Running = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "JavaScript.KeyGen.Running",
-		Other: "key generation running for __seconds__ seconds",
-	}})
-	translations.Keygen.Generated = localizer.MustLocalize(&i18n.LocalizeConfig{DefaultMessage: &i18n.Message{
-		ID:    "JavaScript.KeyGen.Generated",
-		Other: "key generated in __seconds__ seconds",
-	}})
-
-	encoder := json.NewEncoder(w)
-	if err := encoder.Encode(translations); err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-	}
-}
-
-func generateRandomBytes(count int) []byte {
-	randomBytes := make([]byte, count)
-
-	_, err := rand.Read(randomBytes)
-	if err != nil {
-		log.Fatalf("could not read random bytes: %v", err)
-		return nil
-	}
-
-	return randomBytes
-}
-
-func init() {
-	var err error
-	caCertificates = make([]*x509.Certificate, 2)
-	for index, certFile := range []string{"example_ca/sub/ca.crt.pem", "example_ca/root/ca.crt.pem"} {
-		var certBytes []byte
-		if certBytes, err = ioutil.ReadFile(certFile); err != nil {
-			log.Panic(err)
-		}
-		var block *pem.Block
-		if block, _ = pem.Decode(certBytes); block == nil {
-			log.Panicf("no PEM data found in %s", certFile)
-			return
-		}
-		if caCertificates[index], err = x509.ParseCertificate(block.Bytes); err != nil {
-			log.Panic(err)
-		}
-	}
-	log.Infof("read %d CA certificates", len(caCertificates))
-}
-
 func main() {
 	tlsConfig := &tls.Config{
 		CipherSuites: []uint16{
 			tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
 			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 		},
 		NextProtos:               []string{"h2"},
 		PreferServerCipherSuites: true,
 		MinVersion:               tls.VersionTLS12,
 	}
 
-	bundle := i18n.NewBundle(language.English)
+	bundle := loadI18nBundle()
-	bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
-	for _, lang := range []string{"en-US", "de-DE"} {
-		if _, err := bundle.LoadMessageFile(fmt.Sprintf("active.%s.toml", lang)); err != nil {
-			log.Panic(err)
-		}
-	}
-
 	mux := http.NewServeMux()
 
-	var csrfKey []byte = nil
+	csrfKey := initCSRFKey()
 
-	if csrfB64, exists := os.LookupEnv("CSRF_KEY"); exists {
+	mux.Handle("/sign/", handlers.NewCertificateSigningHandler(loadCACertificates()))
-		csrfKey, _ = base64.RawStdEncoding.DecodeString(csrfB64)
+	mux.Handle("/", handlers.NewIndexHandler(bundle))
-		log.Info("read CSRF key from environment variable")
-	}
-	if csrfKey == nil {
-		csrfKey = generateRandomBytes(32)
-		log.Infof(
-			"generated new random CSRF key, set environment variable CSRF_KEY to %s to "+
-				"keep the same key for new sessions",
-			base64.RawStdEncoding.EncodeToString(csrfKey))
-	}
-
-	mux.Handle("/sign/", &signCertificate{})
-	mux.Handle("/", &indexHandler{Bundle: bundle})
 	fileServer := http.FileServer(http.Dir("./public"))
 	mux.Handle("/css/", fileServer)
 	mux.Handle("/js/", fileServer)
-	mux.Handle("/locales/", &jsLocalesHandler{Bundle: bundle})
+	mux.Handle("/locales/", handlers.NewJSLocalesHandler(bundle))
 	server := http.Server{
 		Addr:              ":8000",
 		Handler:           csrf.Protect(csrfKey, csrf.FieldName("csrfToken"), csrf.RequestHeader("X-CSRF-Token"))(mux),
@@ -392,3 +75,64 @@ func main() {
 	log.Infof("received %s, shutting down", s)
 	_ = server.Close()
 }
+
+func loadI18nBundle() *i18n.Bundle {
+	bundle := i18n.NewBundle(language.English)
+	bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
+	for _, lang := range []string{"en-US", "de-DE"} {
+		if _, err := bundle.LoadMessageFile(fmt.Sprintf("active.%s.toml", lang)); err != nil {
+			log.Panic(err)
+		}
+	}
+	return bundle
+}
+
+func initCSRFKey() []byte {
+	var csrfKey []byte = nil
+
+	if csrfB64, exists := os.LookupEnv("CSRF_KEY"); exists {
+		csrfKey, _ = base64.RawStdEncoding.DecodeString(csrfB64)
+		log.Info("read CSRF key from environment variable")
+	}
+	if csrfKey == nil {
+		csrfKey = generateRandomBytes(32)
+		log.Infof(
+			"generated new random CSRF key, set environment variable CSRF_KEY to %s to "+
+				"keep the same key for new sessions",
+			base64.RawStdEncoding.EncodeToString(csrfKey))
+	}
+	return csrfKey
+}
+
+func generateRandomBytes(count int) []byte {
+	randomBytes := make([]byte, count)
+
+	_, err := rand.Read(randomBytes)
+	if err != nil {
+		log.Fatalf("could not read random bytes: %v", err)
+		return nil
+	}
+
+	return randomBytes
+}
+
+func loadCACertificates() (caCertificates []*x509.Certificate) {
+	var err error
+	caCertificates = make([]*x509.Certificate, 2)
+	for index, certFile := range []string{"example_ca/sub/ca.crt.pem", "example_ca/root/ca.crt.pem"} {
+		var certBytes []byte
+		if certBytes, err = ioutil.ReadFile(certFile); err != nil {
+			log.Panic(err)
+		}
+		var block *pem.Block
+		if block, _ = pem.Decode(certBytes); block == nil {
+			log.Panicf("no PEM data found in %s", certFile)
+			return
+		}
+		if caCertificates[index], err = x509.ParseCertificate(block.Bytes); err != nil {
+			log.Panic(err)
+		}
+	}
+	log.Infof("read %d CA certificates", len(caCertificates))
+	return
+}