Merge pull request #98 from NickPresta/decrypt-key

Add support for password-encrypted keys.

auth.go

@@ -17,6 +17,15 @@ type Auth struct {
 	sync.RWMutex
 }
 
+// NewAuth creates a new default Auth.
+func NewAuth() Auth {
+	return Auth{
+		whitelist: make(map[string]struct{}),
+		banned:    make(map[string]struct{}),
+		ops:       make(map[string]struct{}),
+	}
+}
+
 // AllowAnonymous determines if anonymous users are permitted.
 func (a Auth) AllowAnonymous() bool {
 	a.RLock()

cmd.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"bufio"
+	"crypto/x509"
+	"encoding/pem"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -14,6 +16,7 @@ import (
 	"github.com/alexcesaro/log/golog"
 	"github.com/jessevdk/go-flags"
 	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/terminal"
 
 	"github.com/shazow/ssh-chat/chat"
 	"github.com/shazow/ssh-chat/sshd"
@@ -80,21 +83,19 @@ func main() {
 		}
 	}
 
-	privateKey, err := ioutil.ReadFile(privateKeyPath)
+	privateKey, err := readPrivateKey(privateKeyPath)
 	if err != nil {
-		logger.Errorf("Failed to load identity: %v", err)
+		logger.Errorf("Couldn't read private key: %v", err)
 		os.Exit(2)
-		return
 	}
 
 	signer, err := ssh.ParsePrivateKey(privateKey)
 	if err != nil {
 		logger.Errorf("Failed to parse key: %v", err)
 		os.Exit(3)
-		return
 	}
 
-	auth := Auth{}
+	auth := NewAuth()
 	config := sshd.MakeAuth(auth)
 	config.AddHostKey(signer)
 
@@ -102,7 +103,6 @@ func main() {
 	if err != nil {
 		logger.Errorf("Failed to listen on socket: %v", err)
 		os.Exit(4)
-		return
 	}
 	defer s.Close()
 
@@ -150,3 +150,43 @@ func main() {
 	logger.Warningf("Interrupt signal detected, shutting down.")
 	os.Exit(0)
 }
+
+// readPrivateKey attempts to read your private key and possibly decrypt it if it
+// requires a passphrase.
+// This function will prompt for a passphrase on STDIN if the environment variable (`IDENTITY_PASSPHRASE`),
+// is not set.
+func readPrivateKey(privateKeyPath string) ([]byte, error) {
+	privateKey, err := ioutil.ReadFile(privateKeyPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load identity: %v", err)
+	}
+
+	block, rest := pem.Decode(privateKey)
+	if len(rest) > 0 {
+		return nil, fmt.Errorf("extra data when decoding private key")
+	}
+	if !x509.IsEncryptedPEMBlock(block) {
+		return privateKey, nil
+	}
+
+	passphrase := []byte(os.Getenv("IDENTITY_PASSPHRASE"))
+	if len(passphrase) == 0 {
+		fmt.Printf("Enter passphrase: ")
+		passphrase, err = terminal.ReadPassword(int(os.Stdin.Fd()))
+		if err != nil {
+			return nil, fmt.Errorf("couldn't read passphrase: %v", err)
+		}
+		fmt.Println()
+	}
+	der, err := x509.DecryptPEMBlock(block, passphrase)
+	if err != nil {
+		return nil, fmt.Errorf("decrypt failed: %v", err)
+	}
+
+	privateKey = pem.EncodeToMemory(&pem.Block{
+		Type:  block.Type,
+		Bytes: der,
+	})
+
+	return privateKey, nil
+}