title: HMAC-SHA1: How to do it properly in Java?
body: <p>I'm hashing some values using HMAC-SHA1, using the following code in Java:</p>
  
  <pre><code>public static String hmacSha1(String value, String key) {
      try {
          // Get an hmac_sha1 key from the raw key bytes
          byte[] keyBytes = key.getBytes();           
          SecretKeySpec signingKey = new SecretKeySpec(keyBytes, "HmacSHA1");
  
          // Get an hmac_sha1 Mac instance and initialize with the signing key
          Mac mac = Mac.getInstance("HmacSHA1");
          mac.init(signingKey);
  
          // Compute the hmac on input data bytes
          byte[] rawHmac = mac.doFinal(value.getBytes());
  
          // Convert raw bytes to Hex
          byte[] hexBytes = new Hex().encode(rawHmac);
  
          //  Covert array of Hex bytes to a String
          return new String(hexBytes, "UTF-8");
      } catch (Exception e) {
          throw new RuntimeException(e);
      }
  }
  </code></pre>
  
  <p><code>Hex()</code> belongs to <code>org.apache.commons.codec</code></p>
  
  <p>In PHP there's a similar function <code>hash_hmac(algorithm, data, key)</code> that I use to compare the values returned by my Java implementation.</p>
  
  <p>So the first try is:</p>
  
  <pre><code>hash_hmac("sha1", "helloworld", "mykey") // PHP
  </code></pre>
  
  <p>that returns: <code>74ae5a4a3d9996d5918defc2c3d475471bbf59ac</code></p>
  
  <p>My Java function returns <code>74ae5a4a3d9996d5918defc2c3d475471bbf59ac</code> as well.</p>
  
  <p>Ok, it seems working. Then I try to use a more complex key:</p>
  
  <pre><code>hash_hmac("sha1", "helloworld", "PRIE7$oG2uS-Yf17kEnUEpi5hvW/#AFo") // PHP
  </code></pre>
  
  <p>that returns: <code>e98bcc5c5be6f11dc582ae55f520d1ec4ae29f7a</code></p>
  
  <p>While this time my Java impl returns: <code>c19fccf57c613f1868dd22d586f9571cf6412cd0</code></p>
  
  <p>The hash returned by my PHP code is not equal to the value returned by my Java function, and I can't find out why.</p>
  
  <p>Any tips?</p>