<story><title>How Hash Algorithms Work (2007)</title><url>http://www.metamorphosite.com/one-way-hash-encryption-sha1-data-software</url></story><parent_chain><item><author>rkda</author><text>&amp;gt;The word &amp;#x27;cat&amp;#x27; will hash to something that no other word hashes too, but it will always hash to the same thing.&lt;p&gt;Don&amp;#x27;t hashing functions have collisions?</text></item></parent_chain><comment><author>hannob</author><text>&amp;gt; Don&amp;#x27;t hashing functions have collisions?&lt;p&gt;They do. The text is somewhat misleading and not properly explaining that.&lt;p&gt;All hash functions have collisions. But from a cryptographically secure hash function we expect that nobody is able to find such a collision. They exist, but the computational power to find one is not available to humans.</text></comment>
<story><title>How Hash Algorithms Work (2007)</title><url>http://www.metamorphosite.com/one-way-hash-encryption-sha1-data-software</url></story><parent_chain><item><author>rkda</author><text>&amp;gt;The word &amp;#x27;cat&amp;#x27; will hash to something that no other word hashes too, but it will always hash to the same thing.&lt;p&gt;Don&amp;#x27;t hashing functions have collisions?</text></item></parent_chain><comment><author>jasode</author><text>You&amp;#x27;re right but I&amp;#x27;m guessing the writer is thinking of the limited list of English &amp;quot;words&amp;quot;.&lt;p&gt;1.46 x 10^48 = sha1 possible outputs&lt;p&gt;~7.5 x 10^5 = total English words [1]&lt;p&gt;If you computed all ~750,000 hashes for all known English words, none of the sha1 hashes will match &lt;i&gt;sha1(&amp;quot;cat&amp;quot;)&lt;/i&gt;.  I&amp;#x27;m guessing that you still wouldn&amp;#x27;t get a collision if you include all words from all world languages.&lt;p&gt;For &amp;quot;words&amp;quot; to generate a collision, you&amp;#x27;d have to increase the input domain by allowing &amp;quot;words&amp;quot; to mean &lt;i&gt;any&lt;/i&gt; sequence of bytes (e.g. bytes of jpg image or audio file).&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.oxforddictionaries.com&amp;#x2F;explore&amp;#x2F;how-many-words-are-there-in-the-english-language&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.oxforddictionaries.com&amp;#x2F;explore&amp;#x2F;how-many-words-are...&lt;/a&gt;</text></comment>