AWS Creating POST policy base64 encoded + signature

问题

I am trying to generate an AWS POST policy w/ signature in PHP, which will be sent to the client to allow uploading in the browser via javascript AJAX.

I have copied the example at http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html

I have 2 problems:

I cannot generate a correctly encoded base64 string from the policy.

$policy = '{ "expiration": "2013-08-06T12:00:00.000Z", "conditions": [{"bucket": "examplebucket"}, ["starts-with", "$key", "user/user1/"], {"acl": "public-read"}, {"success_action_redirect": "http://acl6.s3.amazonaws.com/successful_upload.html"}, ["starts-with", "$Content-Type", "image/"], {"x-amz-meta-uuid": "14365123651274"}, ["starts-with", "$x-amz-meta-tag", ""], {"x-amz-credential": "AKIAIOSFODNN7EXAMPLE/20130806/us-east-1/s3/aws4_request"}, {"x-amz-algorithm": "AWS4-HMAC-SHA256"}, {"x-amz-date": "20130806T000000Z"}]}';
$base64 = base64_encode($policy);
//Result
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

this is my utf8_encode() policy. when I try to base64 encode it it is different than the examples base64 policy. Can't seem to get it to match no matter what I do. I did notice that changing the date to 2013-08-07T12:00:00.000Z makes it match for that part of the encoded string.

I cannot generate a correct signature via sha256 using a correctly encoded base64 policy.

Creating the Signature from the example's base64 encoded policy:

    //Using this example secret key:
    $secret = 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY';
    $policy = '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';


    <?= hash_hmac('sha256', $policy, $secret); ?>

    //Resulting Signature
    d8ddc156c5d681b42c40a4224c07cdd64b938def8e8c34d616806175cb3c7119

    //Signature in Example
    21496b44de44ccb73d545f1a995c68214c9cb0d41c45a17a5daeec0b1a6db047

Not sure what I am missing here. I also have the PHP SDK, but I was unable to find a way to extract the Policy / Signature so I can send that to the javascript in the browser. Is there a way to generate a policy with my specified conditions from the PHP SDK? I have looked around on the web and in the SDK itself and came up empty...

回答1:

i created my signature with

$policydoc = <<<EOT
{"expiration": "2016-01-01T00:00:00Z",
  "conditions": [ 
    {"bucket": "{$bucket}"}, 
    ["starts-with", "\$key", "uploads/"],
    {"acl": "private"},
    {"success_action_redirect": "$success_action_redirect"},
    ["content-length-range", 0, 1048576]
  ]
}
EOT;

$policydoc = base64_encode($policydoc);
$signature = base64_encode(hash_hmac('sha1', $policydoc,  $provider->getSecretKey(), true));

i think 'sha1' is missing part in yours.

来源：https://stackoverflow.com/questions/28204832/aws-creating-post-policy-base64-encoded-signature

标签

php

amazon-web-services

sdk

signature

policy