Question

我正在尝试使用自定义ruby代码（从官方php库移植到azure）为我的Windows媒体服务文件创建SAS URL。代码看起来像这样：

def create_signature(path = '/', resource = 'b', permissions = 'r', start = '', expiry = '', identifier = '')
  # If resource is a container, remove the last part (which is the filename)
  path = path.split('/').reverse.drop(1).reverse.join('/') if resource == 'c'
  canonicalizedResource = "/mediasvc78m7lfh2gnn2x/#{path}"

  stringToSign  = []
  stringToSign << permissions
  stringToSign << start
  stringToSign << expiry
  stringToSign << canonicalizedResource
  stringToSign << identifier

  stringToSign = stringToSign.join("\n")
  signature    = OpenSSL::HMAC.digest('sha256', wms_api_key, stringToSign.encode(Encoding::UTF_8))
  signature    = Base64.encode64(signature)

  return signature
end

def createSignedQueryString(path = '/', query_string = '', resource = 'b', permissions = 'r', start = '', expiry = '', identifier = '')
  base = 'https://mediasvc78m7lfh2gnn2x.blob.core.windows.net'
  uri  = Addressable::URI.new

  # Parts
  parts       = {}
  parts[:st]  = URI.unescape(start) unless start == ''
  parts[:se]  = URI.unescape(expiry)
  parts[:sr]  = URI.unescape(resource)
  parts[:sp]  = URI.unescape(permissions)
  parts[:si]  = URI.unescape(identifier) unless identifier == ''
  parts[:sig] = URI.unescape( create_signature(path, resource, permissions, start, expiry) )

  uri.query_values = parts
  return "#{base}/#{path}?#{uri.query}"
end

运行时：

puts createSignedQueryString(
  'asset-12514a3b-565f-4150-9543-e3c2b4531428/video.mp4',
  nil,
  'b', 
  'r', 
  (Time.now - 5*60).utc.iso8601, 
  (Time.now + 30*60).utc.iso8601
)

它为我提供了以下网址：https://mediasvc78m7lfh2gnn2x.blob.core.windows.net/asset-12514a3b-565f-4150-9543-e3c2b4531428/video.mp4?se=2014-02-20T12%3A59%3A19Z&sig=RDc9nVMuf1dy%2BPrnzCkA8pZfgry2ZwrF08u9itf4v%2FA%3D%0A&sp=r&sr=b&st=2014-02-20T12%3A24%3A19Z

当我尝试将浏览器指向它时，我得到了：

<Error>
<Code>AuthenticationFailed</Code>
<Message>
Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature. RequestId:ee7fd18f-cd1f-4179-8a58-c8b746d0549c Time:2014-02-20T12:29:27.0468171Z
</Message>
<AuthenticationErrorDetail>
Signature did not match. String to sign used was r 2014-02-20T12:24:19Z 2014-02-20T12:59:19Z /mediasvc78m7lfh2gnn2x/asset-12514a3b-565f-4150-9543-e3c2b4531428/video.mp4
</AuthenticationErrorDetail>
</Error>

您是否知道可能导致该错误的原因（或如何调试？）以及如何处理？提前谢谢。

Answer 1

假设您直接从门户网站使用存储密钥并在wms_api_key变量中使用该存储密钥（或者换句话说，您的wms_api_key是Base64编码的字符串，我相信您需要转换它首先作为用于计算签名的字节数组。您需要执行以下操作：

signature    = OpenSSL::HMAC.digest('sha256', Base64.strict_decode64(wms_api_key), stringToSign.encode(Encoding::UTF_8))

这是基于Github上Azure SDK for Ruby的源代码。

<强>更新

我发现了另外一个问题。如果您注意到SAS URL，您会注意到%0A查询字符串参数末尾的sig，这实际上是一个新的行字符。不知道为什么会这样，但我认为当你执行以下操作时它会自动插入：

signature    = Base64.encode64(signature)

但是，如果我使用strict_encode64代替encode64方法，则不会插入，并且一切都很好。请尝试以下代码：

signature    = Base64.strict_encode64(signature)

我只是尝试过它，它对我很有用。

签名与Azure SAS URL不匹配

1 个答案: