PBKDF2+HMAC hash collisions explained

Some PBKDF2-HMAC-SHA1 collisions that start with the URL of this Hacker News thread:<p><pre><code> $ .&#x2F;brute-force.py &#x27;https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#&#x27; https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#aaaaaaaaaaaaabufhkcn 💥 VID9Qf*}8w9sBtI@TK5k https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#aaaaaaaaaaaaabwwhwta 💥 Bgvi4F~6M#utux ~\H4m https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#aaaaaaaaaaaaacjypwdz 💥 Tn&#x2F;ZyN&#x27;Zs6?d){Ytd?}i https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#aaaaaaaaaaaaaewyefbo 💥 r;9U\DZh!2de#bt &lt;2*o https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7465849#aaaaaaaaaaaaaezrsysb 💥 wl)@eb.1Avvp?|NtT(\c …</code></pre>