# Special API Request Signatures

### **Algorithm**

* Initialize `signatureBase` to an empty string.
* Append the API's HTTP method to `signatureBase`.
* Append `'＆'` to `signatureBase`.
* Append *percent-encoded* full URL path (without `?` or any query parameters) to `signatureBase`.
* Append `'&'` to `signatureBase`.
* Initialize `parameterString` to an empty string.
* For GET / DELETE requests:
  * Sort query parameters in ascending order lexicographically;
  * Append *percent-encoded* key name to `parameterString`;
  * Append an `'='` to `parameterString`;
  * Append *percent-encoded* value to `parameterString`;
  * Append a `'&'` if there are more key value pairs.
* For POST / PUT requests:
  * Append request body as a string to `parameterString`.
* Append *percent-encoded* `parameterString` to `signatureBase`
* Calculate the **SHA-256** hash of `signatureBase` as `hash`.
* Sign`hash` with the private EdDSA key and get `Rx`, `Ry`, and `S`.
* Concatenate `Rx`,`Ry`, and`S` using `','` as: `${Rx},${Ry},${S}`.

### **HTTP Method and URL**

Please make sure you use only the following HTTP methods, in upper case letters.

* GET
* POST
* PUT
* DELETE

Also make sure the HTTPS header is included and is in lower case. For example:

```
https://api3.loopring.io/api/v3/apiKey
```

### **Example**

Actually, so far only 2 API need this special EDDSA API signing -- **updateApiKey** & **cancel order**, let's see how the signatureBase is constructed.

### **Update user API key**

For the above url with the following url query parameters:

```
https://api3.loopring.io/api/v3/apiKey?accountId=10005
```

or

| Query param | Value |
| ----------- | ----- |
| accountId   | 10005 |

`parameterString` shoule be:

```
accountId=10005
```

and `signatureBase` should be:

```
GET&https%3A%2F%2Fapi3.loopring.io%2Fapi%2Fv2%2FapiKey&accountId%3D10005
```

### **Cancel Order**

For the above url with the following url query parameters:

```
https://api3.loopring.io/api/v3/order?accountId=10005&clientOrderId=Sample
```

or

| Query param   | Value  |
| ------------- | ------ |
| accountId     | 10005  |
| clientOrderId | Sample |

`parameterString` should be:

```
accountId=10005&clientOrderId=Sample
```

and `signatureBase` should be:

```
DELETE&https%3A%2F%2Fapi3.loopring.io%2Fapi%2Fv3%2Forder&accountId%3D10005%26clientOrderId%3DSample
```


---

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