refactor: mv utils func

lib/index.js

@@ -1,30 +1,10 @@
 const log = require('log-update')
 const pad = require('left-pad')
+const { replace, xor } = require('./utils')
+
 const ALL_HEX = Array.from(Array(256)).map((v, i) => pad(i.toString(16), 2, 0))
 // <- ['00', '01', ... 'fe', 'ff']
 
-function replace (buf, position, replacement) {
-  let end = position + replacement.length
-  if (position < 0) {
-    return replace(buf, buf.length + position, replacement)
-  }
-  if (end > buf.length) {
-    throw new Error('The replacement will cause the result to overflow.')
-  }
-  return Buffer.from(buf).fill(replacement, position, end)
-}
-
-function xor (x, y) {
-  if (x.length !== y.length) {
-    throw new Error('The length of two buffers is different')
-  }
-  let z = Buffer.alloc(x.length)
-  for (let i = 0; i < z.length; i ++) {
-    z[i] = x[i] ^ y[i]
-  }
-  return z
-}
-
 async function crack (iv, cipher, challenge) {
   let original = Buffer.concat([iv, cipher])
   let size = iv.length

lib/utils.js

@@ -0,0 +1,24 @@
+function replace (buf, position, replacement) {
+  let end = position + replacement.length
+  if (position < 0) {
+    return replace(buf, buf.length + position, replacement)
+  }
+  if (end > buf.length) {
+    throw new Error('The replacement will cause the result to overflow.')
+  }
+  return Buffer.from(buf).fill(replacement, position, end)
+}
+
+function xor (x, y) {
+  if (x.length !== y.length) {
+    throw new Error('The length of two buffers is different')
+  }
+  let z = Buffer.alloc(x.length)
+  for (let i = 0; i < z.length; i ++) {
+    z[i] = x[i] ^ y[i]
+  }
+  return z
+}
+
+exports.replace = replace
+exports.xor = xor