Here’s an easy way to upload directly to S3 from an HTML form. No Java, no Flash. Thanks to @RaamDev for his handy little bit of code for doing HMAC signatures. Based on the documentation from Amazon. Makes use of the AWS SDK for PHP to list the buckets.

Screen shots:

Choosing a bucket


File Selection


After selecting the file


Upload Confirmation

code:


<HTML>
<HEAD>
<TITLE>Upload a file to S3</TITLE>
<link href="style.css" rel="stylesheet" type="text/css" />
</HEAD>
<BODY>
<H1>S3 File Upload</H1>

<?php
error_reporting(0);
$accesskey='XXXXXXXXXXXXXXXX';
$secretkey='XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX';

require_once 'AWSSDKforPHP/sdk.class.php';
if (!class_exists('CFRuntime')) die('No direct access allowed.');
CFCredentials::set(array(
        $name => array(
                'key' => $accesskey,
                'secret' => $secretkey,
                'certificate_authority' => false
        ),
        '@default' => $name
));

$s3 = new AmazonS3();

if(!isset($_GET['bucket'])) {
        echo "<P>Please select a bucket:</P>\n";
        $buckets=$s3->get_bucket_list();
        echo '<FORM ACTION="#">';
        foreach ($buckets as $b) { echo '<INPUT TYPE="radio" name="bucket" value="'.$b.'">'.$b."</INPUT><BR>\n"; }
        echo '<BR><INPUT TYPE="submit" VALUE="Use this bucket">'."\n";

        } else {
        $bucket = $_GET['bucket'];

        $policy='
{"expiration": "2012-01-31T00:00:00Z",
  "conditions": [
    {"bucket": "'.$bucket.'"},
    ["starts-with", "$key", ""],
    {"acl": "public-read"},
    {"success_action_redirect": "http://mt.cdnbuilder.com/s3uploader/success.php"},
    ["starts-with", "$Content-Type", ""]
  ]
}';

/*
 * Calculate HMAC-SHA1 according to RFC2104
 * See http://www.faqs.org/rfcs/rfc2104.html
 */
function hmacsha1($key,$data) {
    $blocksize=64;
    $hashfunc='sha1';
    if (strlen($key)>$blocksize)
        $key=pack('H*', $hashfunc($key));
    $key=str_pad($key,$blocksize,chr(0x00));
    $ipad=str_repeat(chr(0x36),$blocksize);
    $opad=str_repeat(chr(0x5c),$blocksize);
    $hmac = pack(
                'H*',$hashfunc(
                    ($key^$opad).pack(
                        'H*',$hashfunc(
                            ($key^$ipad).$data

                        )
                    )
                )
            );
    return bin2hex($hmac);
}

/*
 * Used to encode a field for Amazon Auth
 * (taken from the Amazon S3 PHP example library)
 */
function hex2b64($str)
{
    $raw = '';
    for ($i=0; $i < strlen($str); $i+=2)
    {
        $raw .= chr(hexdec(substr($str, $i, 2)));
    }
    return base64_encode($raw);
}

/* Create the Amazon S3 Policy that needs to be signed */

/*
 * Base64 encode the Policy Document and then
 * create HMAC SHA-1 signature of the base64 encoded policy
 * using the secret key. Finally, encode it for Amazon Authentication.
 */
$base64_policy = base64_encode($policy);
$signature = hex2b64(hmacsha1($secretkey, $base64_policy));

?>
    <form action="https://<?=$bucket?>.s3.amazonaws.com/" method="post" enctype="multipart/form-data">
      <input type="hidden" name="key" value="${filename}">
      <input type="hidden" name="AWSAccessKeyId" value="<?=$accesskey;?>">
      <input type="hidden" name="acl" value="public-read">
      <input type="hidden" name="success_action_redirect" value="http://your.server.here/success.php">
      <input type="hidden" name="policy" value="<?=$base64_policy?>">
      <input type="hidden" name="signature" value="<?=$signature?>">
      <input type="hidden" name="Content-Type" value="image/jpeg">
      <!-- Include any additional input fields here -->

      <input name="file" type="file">
      <br>
      <input type="submit" value="Upload File to S3 bucket <?=$bucket?>">
    </form>
        <P><A HREF=".">Use a different bucket</A></P>
<?php
}
?>
  </body>
</html>

success.php:

<HTML>
<HEAD>
<TITLE>Upload Success!</TITLE>
<link href="style.css" rel="stylesheet" type="text/css" />
</HEAD>
<BODY>
<H1>Upload Success!</H1>

<?php

echo "<P>Successfully uploaded ".$_GET['key']." to bucket ".$_GET['bucket'].".</P>\n";
$url = "https://".$_GET['bucket'].".s3.amazonaws.com/".$_GET['key'];
echo '<P>Direct URL to the file is <A HREF="'.$url.'">'.$url."</A></P>\n";

include '../footer.php';
?>
</BODY>
</HTML>