PlugHmac

Auth Plug

Installation

The package can be installed by adding plug_hmac to your list of dependencies in mix.exs:

def deps do
  [
    {:plug_hmac, "~> 0.3"}
  ]
end

Usage

Configuration

Add body_reader to your Phoenix's Endpoint

plug Plug.Parsers,
    parsers: [:urlencoded, :multipart, :json],
    pass: ["*/*"],
    body_reader: {PlugHmac.CacheBodyReader, :read_body, []},
    json_decoder: Phoenix.json_library()

Setting client_id & secrets

config :plug_hmac,
  secrets: %{
    "test_id" => "/dXOQgl57dXHT5LxHgtjXrxcbgGrUODvVZjcC8h4iFhTLGVTlwZw0W+vsA2lCOK8"
  }

For Backend

plug PlugHmac, auth_handler: __MODULE__
# or
plug PlugHmac, auth_handler: fun/2

# if set module must def the auth_error/2 function
def auth_error(conn, _error) do
  # you can case error here 
  # or update conn here
  # must return conn
  conn
end

For Client

PlugHmac.make_header("test_id", "GET", "/api/test_auth", "a1=123&a2=456", "body string")
"hmac id=test_id,signature=xpSI4lZe5c%2BxlNe%2BUK6MQU8RHZNTjL1CTgQLbFamoYU%3D,nonce=vrlaY%2BzdC2S7cdWEXLiN"

Principle

客户端在请求时，需要在HTTP的Header增加Authorization:

Authorization: hmac id=test_id,signature=xpSI4lZe5c%2BxlNe%2BUK6MQU8RHZNTjL1CTgQLbFamoYU%3D,nonce=vrlaY%2BzdC2S7cdWEXLiN

PlugHmacplug会校验Authorization值的有效性

参数说明

在开始之前先说明将要用到的参数：

参数名	参数值	说明
Method	GET	请求方法(全大写)
Path	/api/test_auth	请求路径
QueryString	"a1=123&a2=456"	将请求参数用`&`和`=`拼接起来
Body	"body string"	请求的body字符串
ClientID	test_id	由接口提供方提供
SecretKey	qhN8mkCzaxjC1jWD4fDW	由接口提供方提供
Nonce	asd123	随机值字符串

1. Authorization值

在拼接之前先使用 URI-encode，分别对各个参数值进行encode，然后再将其拼接起来，如下：

"hmac " + "id=" + ClientID + ",signature=" + Signature + ",nonce=" + Nonce

2. Signature值

首先按如下顺序拼接各个参数值：

ConcatString = Method+Path+QueryString+Body+Nonce
GET/api/test_autha1=123&a2=456body stringasd123

采用HMAC_SHA256算法使用SecretKey加密ConcatString的值，然后在进行Base64-encode，得到Signature 值，求值公式如下:

hmac.new(SecretKey, ConcatString, hashlib.sha256).digest().encode('base64')
Nop1kEtdf04S8Rr5U409Jmsx8Ic6zeWx2/HJZnLDRuM=