http://localhost:1313/tags/2026/ Recent content in 2026 on Ben Rowland Hugo en-uk Fri, 07 Aug 2026 21:15:31 +0100 http://localhost:1313/software/random-numbers/ Fri, 07 Aug 2026 21:15:31 +0100 http://localhost:1313/software/random-numbers/ <p>I&rsquo;ve wondered a few times how we might generate a one-to-one mapping between a range of integers, and a &ldquo;shuffled&rdquo; counterpart in that range. For example, imagine a website where we expose primary keys as part of the URL path:</p> <p><code>http://www.example.com/pageId=123</code></p> <p>This invites someone to try plugging in different pageId values into the URL, as it would be a fair guess that it just represents a database sequence. A scraper could enumerate all pages on the website by incrementing pageId by 1 on each request.</p>