AWS 创建 POST 策略库 base64 编码 + 签名

我正在尝试生成一个带有 PHP 签名的 AWS POST 策略，该策略将发送到客户端以允许通过 javascript AJAX 在浏览器中上传。

我已经复制了该示例http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html

我有 2 个问题：

1. 我无法从策略生成正确编码的 base64 字符串。

   $policy = '{ "expiration": "2013-08-06T12:00:00.000Z", "conditions": [{"bucket": "examplebucket"}, ["starts-with", "$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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
   

这是我的utf8_encode（）策略。 当我尝试对 base64 进行编码时，它与示例 base64 策略不同。无论我做什么，似乎都无法匹配它。我确实注意到将日期更改为2013-08-07T12:00:00.000Z使其与编码字符串的该部分匹配。

2. 我无法使用正确编码的 base64 策略通过 sha256 生成正确的签名。

从示例的 base64 编码策略创建签名：

    //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

不知道我在这里错过了什么。我也有 PHP SDK，但我无法找到提取策略/签名的方法，以便我可以将其发送到浏览器中的 javascript。有没有办法从 PHP SDK 生成具有我指定条件的策略？我在网络和SDK本身上环顾四周，结果是空的......

$policydoc = <<<EOT
{"expiration": "2016-01-01T00:00:00Z",
  "conditions": [ 
    {"bucket": "{$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));