title: Rust: How to read hex from file
body: <p>I want to read some data from a file in order to xor this with another sequence. 
  The content of the file is</p>
  
  <pre><code>00112233445566778899aabbccddeeff
  </code></pre>
  
  <p>The sequence this should be xored with is</p>
  
  <pre><code>000102030405060708090a0b0c0d0e0f
  </code></pre>
  
  <p>The result should be:</p>
  
  <pre><code>00102030405060708090a0b0c0d0e0f0
  </code></pre>
  
  <p>The reason why i get a differnt result is that rust reads the content as ascii, like this:</p>
  
  <pre><code>buffer: [48, 48, 49, 49, 50, 50, 51, 51, 52, 52, 53, 53, 54, 54, 55, 55]
  buffer: [56, 56, 57, 57, 97, 97, 98, 98, 99, 99, 100, 100, 101, 101, 102, 102]
  </code></pre>
  
  <p>Is there a way to read the content directly to an hex array or how would one convert this?</p>