Qsign

Generate signature for Golang struct value.

Requirements

Go version >= 1.8

Signing Method

It uses the signing method widely used by tencent and wechat APIs.

For example, we have such data to be signed:

appid: wxd930ea5d5a258f4f
mch_id: 10000100
device_info: 1000
body: test
nonce_str: ibuaiVcKdpRxkhJA

First step, we make a query string using the data. Key is sorted by ASCII order. Then we have string A.

A := "appid=wxd930ea5d5a258f4f&body=test&device_info=1000&mch_id=10000100&nonce_str=ibuaiVcKdpRxkhJA"

Next, we prepend or append some secret data to A. Then we have our digest B. Here, we append a secret key.

B := A + "&key=192006250b4c09247ec02edce69f6a2d"
// appid=wxd930ea5d5a258f4f&body=test&device_info=1000&mch_id=10000100&nonce_str=ibuaiVcKdpRxkhJA&key=192006250b4c09247ec02edce69f6a2d

Finaly, calculate the checksum of the digest using some hash method. Then we get the signature.

md5(B)

Usage

Qsign implements the signing method mentioned before. It uses reflection to get structs' fields, determines which fields will appear in the digest. By default field name is used as key. You can asign a "qsign" tag to that field to change key string or ignore that field. Qsign also support "json", "yaml", "xml" and "form" tags optionally.

Tag "qsign" has the highest priority. A field with tag qsign:"-" will be ignored.

data := struct {
	AppId      string `qsign:"appid"`
	MchId      int    `qsign:"mch_id"`
	DeviceInfo string `qsign:"device_info"`
	Body       string `qsign:"body"`
	NonceStr   string `qsign:"nonce_str"`
	IgnoreMe   string `qsign:"-"`
}{
	AppId:      "wxd930ea5d5a258f4f",
	MchId:      10000100,
	DeviceInfo: "1000",
	Body:       "test",
	NonceStr:   "ibuaiVcKdpRxkhJA",
	IgnoreMe:   "won't be used to generate digest",
}

q := qsign.NewQsign(qsign.Options{
	SuffixGenerator: func() string {
		return "&key=192006250b4c09247ec02edce69f6a2d"
	},
})

// digest, _ := q.Digest(data)
// fmt.Printf("%s\n", string(digest))
// appid=wxd930ea5d5a258f4f&body=test&device_info=1000&mch_id=10000100&nonce_str=ibuaiVcKdpRxkhJA&key=192006250b4c09247ec02edce69f6a2d

signature, _ := q.Sign(data)
fmt.Printf("%s\n", string(signature))
// 9a0a8659f005d6984697e2ca0a9cf3b7

Limitations

Array and Slice types of field are not supported.

But if a field type implements the Marshaler, Qsgin will use the result of function MarshalQsgin() string as value in the digest. Note, for using this feature, either the field or the struct must be addressable. For example:

type MyType struct {
	Key   string
	Value string
}

func (m *MyType) MarshalQsign() string {
	return fmt.Sprintf("%s->%s", m.Key, m.Value)
}

func main() {
	data := &struct {
		T MyType `qsign:"t"`
	}{
		T: MyType{"jerray", "qsign"},
	}

	q := qsign.NewQsign(qsign.Options{})

	digest, _ := q.Digest(data)
	fmt.Printf("%s\n", string(digest))
	// t=jerray->qsign
}

License