Merge pull request #227 from jehiah/base64_cookie_encoding_227

Cookie secret encoding?

cookie/cookies.go

@@ -85,8 +85,8 @@ type Cipher struct {
 }
 
 // NewCipher returns a new aes Cipher for encrypting cookie values
-func NewCipher(secret string) (*Cipher, error) {
-	c, err := aes.NewCipher([]byte(secret))
+func NewCipher(secret []byte) (*Cipher, error) {
+	c, err := aes.NewCipher(secret)
 	if err != nil {
 		return nil, err
 	}

cookie/cookies_test.go

@@ -1,6 +1,7 @@
 package cookie
 
 import (
+	"encoding/base64"
 	"testing"
 
 	"github.com/bmizerany/assert"
@@ -9,7 +10,25 @@ import (
 func TestEncodeAndDecodeAccessToken(t *testing.T) {
 	const secret = "0123456789abcdefghijklmnopqrstuv"
 	const token = "my access token"
-	c, err := NewCipher(secret)
+	c, err := NewCipher([]byte(secret))
+	assert.Equal(t, nil, err)
+
+	encoded, err := c.Encrypt(token)
+	assert.Equal(t, nil, err)
+
+	decoded, err := c.Decrypt(encoded)
+	assert.Equal(t, nil, err)
+
+	assert.NotEqual(t, token, encoded)
+	assert.Equal(t, token, decoded)
+}
+
+func TestEncodeAndDecodeAccessTokenB64(t *testing.T) {
+	const secret_b64 = "A3Xbr6fu6Al0HkgrP1ztjb-mYiwmxgNPP-XbNsz1WBk="
+	const token = "my access token"
+
+	secret, err := base64.URLEncoding.DecodeString(secret_b64)
+	c, err := NewCipher([]byte(secret))
 	assert.Equal(t, nil, err)
 
 	encoded, err := c.Encrypt(token)

main.go

@@ -55,7 +55,7 @@ func main() {
 	flagSet.String("proxy-prefix", "/oauth2", "the url root path that this proxy should be nested under (e.g. /<oauth2>/sign_in)")
 
 	flagSet.String("cookie-name", "_oauth2_proxy", "the name of the cookie that the oauth_proxy creates")
-	flagSet.String("cookie-secret", "", "the seed string for secure cookies")
+	flagSet.String("cookie-secret", "", "the seed string for secure cookies (optionally base64 encoded)")
 	flagSet.String("cookie-domain", "", "an optional cookie domain to force cookies to (ie: .yourcompany.com)*")
 	flagSet.Duration("cookie-expire", time.Duration(168)*time.Hour, "expire timeframe for cookie")
 	flagSet.Duration("cookie-refresh", time.Duration(0), "refresh the cookie after this duration; 0 to disable")

oauthproxy.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"encoding/base64"
+	b64 "encoding/base64"
 	"errors"
 	"fmt"
 	"html/template"
@@ -164,10 +164,9 @@ func NewOAuthProxy(opts *Options, validator func(string) bool) *OAuthProxy {
 	var cipher *cookie.Cipher
 	if opts.PassAccessToken || (opts.CookieRefresh != time.Duration(0)) {
 		var err error
-		cipher, err = cookie.NewCipher(opts.CookieSecret)
+		cipher, err = cookie.NewCipher(secretBytes(opts.CookieSecret))
 		if err != nil {
-			log.Fatal("error creating AES cipher with "+
-				"cookie-secret ", opts.CookieSecret, ": ", err)
+			log.Fatal("cookie-secret error: ", err)
 		}
 	}
 
@@ -626,7 +625,7 @@ func (p *OAuthProxy) CheckBasicAuth(req *http.Request) (*providers.SessionState,
 	if len(s) != 2 || s[0] != "Basic" {
 		return nil, fmt.Errorf("invalid Authorization header %s", req.Header.Get("Authorization"))
 	}
-	b, err := base64.StdEncoding.DecodeString(s[1])
+	b, err := b64.StdEncoding.DecodeString(s[1])
 	if err != nil {
 		return nil, err
 	}

oauthproxy_test.go

@@ -427,7 +427,7 @@ func NewProcessCookieTest(opts ProcessCookieTestOpts) *ProcessCookieTest {
 	pc_test.opts = NewOptions()
 	pc_test.opts.ClientID = "bazquux"
 	pc_test.opts.ClientSecret = "xyzzyplugh"
-	pc_test.opts.CookieSecret = "0123456789abcdef"
+	pc_test.opts.CookieSecret = "0123456789abcdefabcd"
 	// First, set the CookieRefresh option so proxy.AesCipher is created,
 	// needed to encrypt the access_token.
 	pc_test.opts.CookieRefresh = time.Hour

options.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"crypto"
+	"encoding/base64"
 	"fmt"
 	"net/url"
 	"os"
@@ -156,17 +157,25 @@ func (o *Options) Validate() error {
 	if o.PassAccessToken || (o.CookieRefresh != time.Duration(0)) {
 		valid_cookie_secret_size := false
 		for _, i := range []int{16, 24, 32} {
-			if len(o.CookieSecret) == i {
+			if len(secretBytes(o.CookieSecret)) == i {
 				valid_cookie_secret_size = true
 			}
 		}
+		var decoded bool
+		if string(secretBytes(o.CookieSecret)) != o.CookieSecret {
+			decoded = true
+		}
 		if valid_cookie_secret_size == false {
+			var suffix string
+			if decoded {
+				suffix = fmt.Sprintf(" note: cookie secret was base64 decoded from %q", o.CookieSecret)
+			}
 			msgs = append(msgs, fmt.Sprintf(
 				"cookie_secret must be 16, 24, or 32 bytes "+
 					"to create an AES cipher when "+
 					"pass_access_token == true or "+
-					"cookie_refresh != 0, but is %d bytes",
-				len(o.CookieSecret)))
+					"cookie_refresh != 0, but is %d bytes.%s",
+				len(secretBytes(o.CookieSecret)), suffix))
 		}
 	}
 
@@ -251,3 +260,26 @@ func parseSignatureKey(o *Options, msgs []string) []string {
 	}
 	return msgs
 }
+
+func addPadding(secret string) string {
+	padding := len(secret) % 4
+	switch padding {
+	case 1:
+		return secret + "==="
+	case 2:
+		return secret + "=="
+	case 3:
+		return secret + "="
+	default:
+		return secret
+	}
+}
+
+// secretBytes attempts to base64 decode the secret, if that fails it treats the secret as binary
+func secretBytes(secret string) []byte {
+	b, err := base64.URLEncoding.DecodeString(addPadding(secret))
+	if err == nil {
+		return []byte(addPadding(string(b)))
+	}
+	return []byte(secret)
+}

options_test.go

@@ -160,7 +160,7 @@ func TestCookieRefreshMustBeLessThanCookieExpire(t *testing.T) {
 	o := testOptions()
 	assert.Equal(t, nil, o.Validate())
 
-	o.CookieSecret = "0123456789abcdef"
+	o.CookieSecret = "0123456789abcdefabcd"
 	o.CookieRefresh = o.CookieExpire
 	assert.NotEqual(t, nil, o.Validate())
 
@@ -168,6 +168,31 @@ func TestCookieRefreshMustBeLessThanCookieExpire(t *testing.T) {
 	assert.Equal(t, nil, o.Validate())
 }
 
+func TestBase64CookieSecret(t *testing.T) {
+	o := testOptions()
+	assert.Equal(t, nil, o.Validate())
+
+	// 32 byte, base64 (urlsafe) encoded key
+	o.CookieSecret = "yHBw2lh2Cvo6aI_jn_qMTr-pRAjtq0nzVgDJNb36jgQ="
+	assert.Equal(t, nil, o.Validate())
+
+	// 32 byte, base64 (urlsafe) encoded key, w/o padding
+	o.CookieSecret = "yHBw2lh2Cvo6aI_jn_qMTr-pRAjtq0nzVgDJNb36jgQ"
+	assert.Equal(t, nil, o.Validate())
+
+	// 24 byte, base64 (urlsafe) encoded key
+	o.CookieSecret = "Kp33Gj-GQmYtz4zZUyUDdqQKx5_Hgkv3"
+	assert.Equal(t, nil, o.Validate())
+
+	// 16 byte, base64 (urlsafe) encoded key
+	o.CookieSecret = "LFEqZYvYUwKwzn0tEuTpLA=="
+	assert.Equal(t, nil, o.Validate())
+
+	// 16 byte, base64 (urlsafe) encoded key, w/o padding
+	o.CookieSecret = "LFEqZYvYUwKwzn0tEuTpLA"
+	assert.Equal(t, nil, o.Validate())
+}
+
 func TestValidateSignatureKey(t *testing.T) {
 	o := testOptions()
 	o.SignatureKey = "sha1:secret"

providers/github.go

@@ -3,11 +3,11 @@ package providers
 import (
 	"encoding/json"
 	"fmt"
-	"strings"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"net/url"
+	"strings"
 )
 
 type GitHubProvider struct {

providers/session_state_test.go

@@ -13,9 +13,9 @@ const secret = "0123456789abcdefghijklmnopqrstuv"
 const altSecret = "0000000000abcdefghijklmnopqrstuv"
 
 func TestSessionStateSerialization(t *testing.T) {
-	c, err := cookie.NewCipher(secret)
+	c, err := cookie.NewCipher([]byte(secret))
 	assert.Equal(t, nil, err)
-	c2, err := cookie.NewCipher(altSecret)
+	c2, err := cookie.NewCipher([]byte(altSecret))
 	assert.Equal(t, nil, err)
 	s := &SessionState{
 		Email:        "user@domain.com",