From d4fe1400d20900c6e4e761c13fce61d6fa0ecca1 Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@nym.se>
Date: Tue, 7 Jan 2014 22:04:23 +0100
Subject: [PATCH] Longer RSA key and stronger node ID hash (ref #23)

---
 tls.go | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/tls.go b/tls.go
index e0e5a486..a8a0e12a 100644
--- a/tls.go
+++ b/tls.go
@@ -3,7 +3,7 @@ package main
 import (
 	"crypto/rand"
 	"crypto/rsa"
-	"crypto/sha1"
+	"crypto/sha256"
 	"crypto/tls"
 	"crypto/x509"
 	"crypto/x509/pkix"
@@ -12,11 +12,12 @@ import (
 	"math/big"
 	"os"
 	"path"
+	"strings"
 	"time"
 )
 
 const (
-	tlsRSABits = 2048
+	tlsRSABits = 3072
 	tlsName    = "syncthing"
 )
 
@@ -25,13 +26,15 @@ func loadCert(dir string) (tls.Certificate, error) {
 }
 
 func certId(bs []byte) string {
-	hf := sha1.New()
+	hf := sha256.New()
 	hf.Write(bs)
 	id := hf.Sum(nil)
-	return base32.StdEncoding.EncodeToString(id)
+	return strings.Trim(base32.StdEncoding.EncodeToString(id), "=")
 }
 
 func newCertificate(dir string) {
+	infoln("Generating RSA certificate and key...")
+
 	priv, err := rsa.GenerateKey(rand.Reader, tlsRSABits)
 	fatalErr(err)
 
@@ -47,7 +50,7 @@ func newCertificate(dir string) {
 		NotAfter:  notAfter,
 
 		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
-		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
 		BasicConstraintsValid: true,
 	}
 
@@ -58,11 +61,11 @@ func newCertificate(dir string) {
 	fatalErr(err)
 	pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
 	certOut.Close()
-	okln("Created TLS certificate file")
+	okln("Created RSA certificate file")
 
 	keyOut, err := os.OpenFile(path.Join(dir, "key.pem"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	fatalErr(err)
 	pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
 	keyOut.Close()
-	okln("Created TLS key file")
+	okln("Created RSA key file")
 }