Adds an internal library for JWS / JWT encoding

jwt/base64.go

@@ -0,0 +1,32 @@
+package jwt
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strings"
+)
+
+// Base64Encode encodes a payload of data as a string, like specified
+// in RFC 7515 (no trailing '='
+func Base64Encode(b []byte) string {
+	return strings.TrimRight(base64.URLEncoding.EncodeToString(b), "=")
+}
+
+// Base64Decode decodes a payload of data as a []byte, like specified
+// in RFC 7515 (no trailing '=')
+func Base64Decode(s string) ([]byte, error) {
+	switch len(s) % 4 {
+	case 2:
+		s += "=="
+	case 3:
+		s += "="
+	case 1:
+		return nil, fmt.Errorf("jwt: Invalid base64 string (length:%d %% 4 == 1): '%s'", len(s), s)
+	}
+	d, err := base64.URLEncoding.DecodeString(s)
+	if err != nil {
+		return nil, fmt.Errorf("jwt: %s", err)
+	}
+	return d, nil
+
+}