Adds JWS encode and decode

It also adds interfaces Signer and HS256 and RS256 implementation.

jwt/base64_test.go

@@ -1,6 +1,7 @@
 package jwt
 
 import (
+	"encoding/base64"
 	"testing"
 
 	. "gopkg.in/check.v1"
@@ -16,19 +17,20 @@ var _ = Suite(&Base64Suite{})
 
 type dataAndEncode struct {
 	data    []byte
-	encoded string
+	encoded []byte
 }
 
 func (s *Base64Suite) TestEncodeWithNoTrailing(c *C) {
 	data := []dataAndEncode{
-		{[]byte{0, 0, 0}, "AAAA"}, //With trailing Should be AAAA
-		{[]byte{0, 0}, "AAA"},     //With trailing Should be AAA=
-		{[]byte{0}, "AA"},         //With trailing Should be AA==
+		{[]byte{0, 0, 0}, []byte("AAAA")}, //With trailing Should be AAAA
+		{[]byte{0, 0}, []byte("AAA")},     //With trailing Should be AAA=
+		{[]byte{0}, []byte("AA")},         //With trailing Should be AA==
 	}
 
 	for _, d := range data {
-		res := Base64Encode(d.data)
-		c.Check(res, Equals, d.encoded)
+		res := make([]byte, Base64EncodedBufferLen(len(d.data)))
+		base64.URLEncoding.Encode(res, d.data)
+		c.Check(res[:Base64EncodedStrippedLen(len(d.data))], DeepEquals, d.encoded)
 	}
 
 }
@@ -41,11 +43,12 @@ func (s *Base64Suite) TestDecodeWithNoTrailing(c *C) {
 	}
 
 	for encoded, expected := range data {
-		res, err := Base64Decode(encoded)
+		res := make([]byte, Base64DecodedLenFromStripped(len(encoded)))
+		err := Base64Decode(res, []byte(encoded))
 		if c.Check(err, IsNil) == false {
 			continue
 		}
-		c.Check(res, DeepEquals, expected)
+		c.Check(res[:Base64DecodedStrippedLen(len(encoded))], DeepEquals, expected)
 	}
 }
 
@@ -56,8 +59,8 @@ func (s *Base64Suite) TestDetectBadFormat(c *C) {
 	}
 
 	for encoded, errorMatches := range data {
-		res, err := Base64Decode(encoded)
+		res := make([]byte, Base64DecodedLenFromStripped(len(encoded)))
+		err := Base64Decode(res, []byte(encoded))
 		c.Check(err, ErrorMatches, errorMatches)
-		c.Check(res, IsNil)
 	}
 }