From dca408e85f0ae0b78c25661a594f1dabfb61f1c7 Mon Sep 17 00:00:00 2001
From: James Elliott <james-d-elliott@users.noreply.github.com>
Date: Sun, 29 Jan 2023 10:33:51 +1100
Subject: [PATCH] feat(protocol): ignore padding for base64 url encoding (#95)

This adds support to ignore the trailing padding of base64 URL encoded bytes.

Closes #93
---
 protocol/attestation_test.go | 6 +++---
 protocol/base64.go           | 5 +++++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/protocol/attestation_test.go b/protocol/attestation_test.go
index 2bee34d..cfe5e24 100644
--- a/protocol/attestation_test.go
+++ b/protocol/attestation_test.go
@@ -91,7 +91,7 @@ var testAttestationOptions = []string{
 		"user": {
 			"name": "self",
 			"displayName": "self",
-			"id": "2iEAAAAAAAAAAA"
+			"id": "2iEAAAAAAAAAAA=="
 		},
 		"pubKeyCredParams": [
 			{
@@ -116,7 +116,7 @@ var testAttestationOptions = []string{
 		"user": {
 			"name": "flort",
 			"displayName": "flort",
-			"id": "1DMAAAAAAAAAAA"
+			"id": "1DMAAAAAAAAAAA=="
 		},
 		"pubKeyCredParams": [
 			{
@@ -142,7 +142,7 @@ var testAttestationOptions = []string{
 		  "user": {
 			"name": "testuser1",
 			"displayName": "testuser1",
-			"id": "1zMAAAAAAAAAAA"
+			"id": "1zMAAAAAAAAAAA=="
 		  },
 		  "pubKeyCredParams": [
 			{
diff --git a/protocol/base64.go b/protocol/base64.go
index 99362b2..37a151b 100644
--- a/protocol/base64.go
+++ b/protocol/base64.go
@@ -22,8 +22,13 @@ func (e *URLEncodedBase64) UnmarshalJSON(data []byte) error {
 		return nil
 	}
 
+	// TODO: Investigate this line. It is commented as trimming the leading spaces but appears to trim the leading and trailing double quotes instead.
 	// Trim the leading spaces
 	data = bytes.Trim(data, "\"")
+
+	// Trim the trailing equal characters.
+	data = bytes.TrimRight(data, "=")
+
 	out := make([]byte, base64.RawURLEncoding.DecodedLen(len(data)))
 	n, err := base64.RawURLEncoding.Decode(out, data)
 	if err != nil {