wlib · June 12, 2025 03:08 · Jun 12, 2025
diff --git a/makeRandomPassword.ts b/makeRandomPassword.ts
@@ -0,0 +1,33 @@
+const basicLatin = String.fromCharCode(...range(32, 127))
+
+const makeRandomPassword = ({
+  length = 32,
+  characters = basicLatin
+}: {
+  /** Max 256 */
+  length?: number,
+  characters?: string | ReadonlyArray<string>
+} = {}) => {
+  const entropyPerCharacter = 8
+  const statesPerCharacter = 2 ** entropyPerCharacter
+
+  if (characters.length > statesPerCharacter)
+    throw new Error(`Character count (${characters.length}) must not exceed 2^8 (256)`)
+
+  const limit = statesPerCharacter - (statesPerCharacter % characters.length)
+
+  const randomValuesUnderLimit: number[] = []
+  while (randomValuesUnderLimit.length < length) {
+    const randomValues = crypto.getRandomValues(
+      new Uint8Array(length - randomValuesUnderLimit.length)
+    )
+    for (const randomValue of randomValues)
+      if (randomValue < limit)
+        randomValuesUnderLimit.push(randomValue)
+  }
+
+  let result = ""
+  for (const n of randomValuesUnderLimit)
+    result += characters[n % characters.length]
+  return result
+}