use raw base64 as defined by rfc7515

encoding.go

@@ -0,0 +1,7 @@
+// Copyright (C) 2018 Marius Schellenberger
+
+package jwt
+
+import "encoding/base64"
+
+var enc = base64.RawURLEncoding

jwt.go

@@ -6,7 +6,6 @@ package jwt
 import (
 	"crypto/hmac"
 	"crypto/rand"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"io"
@@ -210,9 +209,9 @@ func (jwt *JWT) Sign(t *Token) (err error) {
 	if err != nil {
 		return
 	}
-	t.data = base64.URLEncoding.EncodeToString(head) + TokenSeparator + base64.URLEncoding.EncodeToString(claims)
+	t.data = enc.EncodeToString(head) + TokenSeparator + enc.EncodeToString(claims)
 	t.rawSignature = jwt.sum(t.data, h)
-	t.signature = base64.URLEncoding.EncodeToString(t.rawSignature)
+	t.signature = enc.EncodeToString(t.rawSignature)
 	t.raw = t.data + TokenSeparator + t.signature
 	return
 }

token.go

@@ -3,7 +3,6 @@
 package jwt
 
 import (
-	"encoding/base64"
 	"encoding/json"
 	"strings"
 )
@@ -75,7 +74,7 @@ func DecodeToken(token string) (t *Token, err error) {
 		}
 	}
 	t = new(Token)
-	header, err := base64.URLEncoding.DecodeString(parts[0])
+	header, err := enc.DecodeString(parts[0])
 	if err != nil {
 		return
 	}
@@ -83,7 +82,7 @@ func DecodeToken(token string) (t *Token, err error) {
 	if err != nil {
 		return
 	}
-	claims, err := base64.URLEncoding.DecodeString(parts[1])
+	claims, err := enc.DecodeString(parts[1])
 	if err != nil {
 		return
 	}
@@ -91,7 +90,7 @@ func DecodeToken(token string) (t *Token, err error) {
 	if err != nil {
 		return
 	}
-	t.rawSignature, err = base64.URLEncoding.DecodeString(parts[2])
+	t.rawSignature, err = enc.DecodeString(parts[2])
 	t.signature = parts[2]
 	t.data = parts[0] + TokenSeparator + parts[1]
 	t.raw = token