PHP: md5 - Manual

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value='help-translate.php'>Other</option> </select> </fieldset> </form> </div> </div><div id="function.md5" class="refentry"> <div class="refnamediv"> <h1 class="refname">md5</h1> <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">md5</span> — <span class="dc-title">Calculate the md5 hash of a string</span></p> </div> <div id="function.md5-refsynopsisdiv"> <div class="warning"><strong class="warning">Warning</strong> <p class="para"> It is not recommended to use this function to secure passwords, due to the fast nature of this hashing algorithm. See the <a href="faq.passwords.php#faq.passwords.fasthash" class="link">Password Hashing FAQ</a> for details and best practices. </p> </div> </div> <div class="refsect1 description" id="refsect1-function.md5-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="methodname"><strong>md5</strong></span>(<span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$string</code></span>, <span class="methodparam"><span class="type"><a href="language.types.boolean.php" class="type bool">bool</a></span> <code class="parameter">$binary</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.false">false</a></code></strong></span></span>): <span class="type"><a href="language.types.string.php" class="type string">string</a></span></div> <p class="para rdfs-comment"> Calculates the MD5 hash of <code class="parameter">string</code> using the <a href="https://datatracker.ietf.org/doc/html/rfc1321" class="link external">» RSA Data Security, Inc. MD5 Message-Digest Algorithm</a>, and returns that hash. </p> </div> <div class="refsect1 parameters" id="refsect1-function.md5-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt><code class="parameter">string</code></dt> <dd> <p class="para"> The string. </p> </dd> <dt><code class="parameter">binary</code></dt> <dd> <p class="para"> If the optional <code class="parameter">binary</code> is set to <strong><code><a href="reserved.constants.php#constant.true">true</a></code></strong>, then the md5 digest is instead returned in raw binary format with a length of 16. </p> </dd> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.md5-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the hash as a 32-character hexadecimal number. </p> </div> <div class="refsect1 examples" id="refsect1-function.md5-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-4986"> <p><strong>Example #1 A <span class="function"><strong>md5()</strong></span> example</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$str </span><span style="color: #007700">= </span><span style="color: #DD0000">'apple'</span><span style="color: #007700">;<br /><br />if (</span><span style="color: #0000BB">md5</span><span style="color: #007700">(</span><span style="color: #0000BB">$str</span><span style="color: #007700">) === </span><span style="color: #DD0000">'1f3870be274f6c49b3e31a0c6728957f'</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Would you like a green or red apple?"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 seealso" id="refsect1-function.md5-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li><span class="function"><a href="function.hash.php" class="function" rel="rdfs-seeAlso">hash()</a> - Generate a hash value (message digest)</span></li> <li><span class="function"><a href="function.password-hash.php" class="function" rel="rdfs-seeAlso">password_hash()</a> - Creates a password hash</span></li> </ul> </p> </div> </div> <div class="contribute"> <h3 class="title">Found A Problem?</h3> <div> </div> <div class="edit-bug"> <a href="https://github.com/php/doc-base/blob/master/README.md" title="This will take you to our contribution guidelines on GitHub" target="_blank" rel="noopener noreferrer">Learn How To Improve This Page</a> • <a href="https://github.com/php/doc-en/blob/master/reference/strings/functions/md5.xml">Submit a Pull Request</a> • <a href="https://github.com/php/doc-en/issues/new?body=From%20manual%20page:%20https:%2F%2Fphp.net%2Ffunction.md5%0A%0A---">Report a Bug</a> </div> </div><section id="usernotes"> <div class="head"> <span class="action"><a href="/manual/add-note.php?sect=function.md5&repo=en&redirect=https://www.php.net/manual/en/function.md5.php">＋<small>add a note</small></a></span> <h3 class="title">User Contributed Notes <span class="count">2 notes</span></h3> </div><div id="allnotes"> <div class="note" id="125757"> <div class="votes"> <div id="Vu125757"> <a href="/manual/vote-note.php?id=125757&page=function.md5&vote=up" title="Vote up!" class="usernotes-voteu">up</a> </div> <div id="Vd125757"> <a href="/manual/vote-note.php?id=125757&page=function.md5&vote=down" title="Vote down!" class="usernotes-voted">down</a> </div> <div class="tally" id="V125757" title="55% like this..."> 15 </div> </div> <a href="#125757" class="name"> <strong class="user"><em>yiminrong at yahoo dot ca</em></strong></a><a class="genanchor" href="#125757"> ¶</a><div class="date" title="2021-02-02 01:37"><strong>4 years ago</strong></div> <div class="text" id="Hcom125757"> <div class="phpcode"><code><span class="html">Regarding Ray Paseur's comment, the strings hash to:<br /><br />0e462097431906509019562988736854<br />0e830400451993494058024219903391<br /><br />The odds of getting a hash exactly matching the format /^0+e[0-9]+$/ are not high but are also not negligible.<br /><br />It should be added as a general warning for all hash functions to always use the triple equals === for comparison.<br /><br />Actually, the warning should be in the operators section when comparing string values! There are lots of warnings about string comparisons, but nothing specific about the format /^0+e[0-9]+$/.</span></code></div> </div> </div> <div class="note" id="123392"> <div class="votes"> <div id="Vu123392"> <a href="/manual/vote-note.php?id=123392&page=function.md5&vote=up" title="Vote up!" class="usernotes-voteu">up</a> </div> <div id="Vd123392"> <a href="/manual/vote-note.php?id=123392&page=function.md5&vote=down" title="Vote down!" class="usernotes-voted">down</a> </div> <div class="tally" id="V123392" title="51% like this..."> 5 </div> </div> <a href="#123392" class="name"> <strong class="user"><em>Ray.Paseur sometimes uses Gmail</em></strong></a><a class="genanchor" href="#123392"> ¶</a><div class="date" title="2018-12-01 05:10"><strong>6 years ago</strong></div> <div class="text" id="Hcom123392"> <div class="phpcode"><code><span class="html">md5('240610708') == md5('QNKCDZO')<br /><br />This comparison is true because both md5() hashes start '0e' so PHP type juggling understands these strings to be scientific notation. By definition, zero raised to any power is zero.</span></code></div> </div> </div></div> <div class="foot"><a href="/manual/add-note.php?sect=function.md5&repo=en&redirect=https://www.php.net/manual/en/function.md5.php">＋<small>add a note</small></a></div> </section> </section> <aside class='layout-menu'> <ul class='parent-menu-list'> <li> <a href="ref.strings.php">String Functions</a> <ul class='child-menu-list'> <li class=""> <a href="function.addcslashes.php" title="addcslashes">addcslashes</a> </li> <li class=""> <a href="function.addslashes.php" title="addslashes">addslashes</a> </li> <li class=""> <a href="function.bin2hex.php" title="bin2hex">bin2hex</a> </li> <li class=""> <a href="function.chop.php" title="chop">chop</a> </li> <li class=""> <a href="function.chr.php" title="chr">chr</a> </li> <li class=""> <a href="function.chunk-split.php" title="chunk_split">chunk_split</a> </li> <li class=""> <a href="function.convert-uudecode.php" 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