<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>est</author><text>tl;dr collision by appending data at the end of .jpeg file.&lt;p&gt;&amp;gt; The chosen prefix collision attack works by repeatedly adding &amp;#x27;near collision&amp;#x27; blocks which gradually work to  eliminate the differences in the internal MD5 state until they are the same&lt;p&gt;&amp;gt; This type of collision is has been termed a chosen prefix collision. In this case the image data is the prefix or to be more exact the internal state of the MD5 algorithm after processing the image is. You can&amp;#x27;t see the added binary data at the end of jpeg images as it is preceded with an End Of Image JPEG marker.</text><parent_chain></parent_chain></comment><story><title>How I created two images with the same MD5 hash</title><url>http://natmchugh.blogspot.com/2014/10/how-i-created-two-images-with-same-md5.html</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>hrjet</author><text>Do I understand this right: if the length of the original file is specified along with the hash, then such attacks are not trivial?</text><parent_chain></parent_chain></comment><story><title>How I created two images with the same MD5 hash</title><url>http://natmchugh.blogspot.com/2014/10/how-i-created-two-images-with-same-md5.html</url></story>