05 February 2013

Checking the hash of a file

You know when you download a file and you're informed what the hash is, so you can verify your download? We'll I've often seen that and have a working knowledge of hash functions but have never bothered to try it.

Anyway, I thought I'd give it a go, and I'm pleased to say its incredibly easy if you have a CF server kicking around:

<cffile action="read" file="#form.fileupload#" variable="variables.myFile" />

Here's a slightly more completed code fragment if it helps:
<div class="jumbotron">
    <h1>Hash Your File!</h1>
    <cfif structKeyExists(form, "fileupload")>
        <cffile action="read" file="#form.fileupload#" variable="variables.myFile" />
        <p class="alert alert-info"><cfoutput>#hash(variables.myFile,"#form.sel_hash#")#</cfoutput></p>
        <p class="lead">I help you calculate the hash of a file</p>
    <form class=".form-horizontal" method="POST" enctype="multipart/form-data" action="test3.cfm">
        <select name="sel_hash">
            <option value="MD5">MD5</option>
            <option value="SHA">SHA</option>
            <option value="SHA-256">SHA-256</option>
            <option value="SHA-384">SHA-384</option>
            <option value="SHA-512">SHA-512</option>
        <br />
        <div class="fileinputs">
            <input name="fileupload" type="file" />
        <br /><br />
        <button type="submit" class="btn btn-primary">Submit</button>
</div><!-- /jumbotron -->

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