Random secret generator for AES-256-CBC

AES-256-CBC-keygen.php

//JS Version
var charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',
randomString = ''

for (var i = 0; i < length; i++) {
  var randomPos = Math.floor(Math.random() * charSet.length)
  randomString += charSet.substring(randomPos, randomPos + 1)
}

return randomString

// PHP version
$charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
$randomString = '';
for ($i = 0; $i < 32; $i++) {
  $randomPos = floor(((float)rand()/(float)getrandmax()) * strlen($charSet));
  $randomString .= substr($charSet, $randomPos, 1);
}