diff --git a/random-substitution-cipher/index.js b/random-substitution-cipher/index.js
new file mode 100644
index 0000000..6850b42
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+++ b/random-substitution-cipher/index.js
@@ -0,0 +1,7 @@
+// https://www.codewars.com/kata/random-substitution-cipher/javascript
+
+function randomSub() {
+  const alph = 'abcdefghijklmnopqrstuvwxyz'.split``;
+  const rnd = alph.slice().sort(() => Math.random()-0.5);
+  return alph.reduce((res, k, i) => (res[k] = rnd[i], res), {});
+}
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