1 files changed, 31 insertions, 0 deletions
diff --git a/cli/js/get_random_values.ts b/cli/js/get_random_values.ts
new file mode 100644
index 000000000..e54f34785
--- /dev/null
+++ b/cli/js/get_random_values.ts
@@ -0,0 +1,31 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as dispatch from "./dispatch.ts";
+import { sendSync } from "./dispatch_json.ts";
+import { assert } from "./util.ts";
+
+/** Synchronously collects cryptographically secure random values. The
+ * underlying CSPRNG in use is Rust's `rand::rngs::ThreadRng`.
+ *
+ *       const arr = new Uint8Array(32);
+ *       crypto.getRandomValues(arr);
+ */
+export function getRandomValues<
+  T extends
+    | Int8Array
+    | Uint8Array
+    | Uint8ClampedArray
+    | Int16Array
+    | Uint16Array
+    | Int32Array
+    | Uint32Array
+>(typedArray: T): T {
+  assert(typedArray !== null, "Input must not be null");
+  assert(typedArray.length <= 65536, "Input must not be longer than 65536");
+  const ui8 = new Uint8Array(
+    typedArray.buffer,
+    typedArray.byteOffset,
+    typedArray.byteLength
+  );
+  sendSync(dispatch.OP_GET_RANDOM_VALUES, {}, ui8);
+  return typedArray;
+}