1 files changed, 17 insertions, 0 deletions
diff --git a/std/jwt/_algorithm.ts b/std/jwt/_algorithm.ts
new file mode 100644
index 000000000..c9c5257e1
--- /dev/null
+++ b/std/jwt/_algorithm.ts
@@ -0,0 +1,17 @@
+/*
+ * JSW §1: Cryptographic algorithms and identifiers for use with this specification
+ * are described in the separate JSON Web Algorithms (JWA) specification:
+ * https://www.rfc-editor.org/rfc/rfc7518
+ */
+export type Algorithm = "none" | "HS256" | "HS512";
+export type AlgorithmInput = Algorithm | Array<Exclude<Algorithm, "none">>;
+/**
+ * Verify the algorithm
+ * @param algorithm as string or multiple algorithms in an array excluding 'none'
+ * @param the algorithm from the jwt header
+ */
+export function verify(algorithm: AlgorithmInput, jwtAlg: string): boolean {
+  return Array.isArray(algorithm)
+    ? (algorithm as string[]).includes(jwtAlg)
+    : algorithm === jwtAlg;
+}