1 files changed, 13 insertions, 0 deletions
diff --git a/packages/server/src/helpers/isBase64URLString.ts b/packages/server/src/helpers/isBase64URLString.ts
new file mode 100644
index 0000000..09a6404
--- /dev/null
+++ b/packages/server/src/helpers/isBase64URLString.ts
@@ -0,0 +1,13 @@
+// Base64URL, with optional padding
+const base64urlRegEx = /^([0-9a-zA-Z-_]{4})*(([0-9a-zA-Z-_]{2}(==)?)|([0-9a-zA-Z-_]{3}=?))?$/;
+
+/**
+ * Check to see if a string only contains valid Base64URL values
+ */
+export default function isBase64URLString(value: string): boolean {
+  if (!value) {
+    return false;
+  }
+
+  return base64urlRegEx.test(value);
+}