# Download, upload, or purchase certificates - DownloadCertificate

## Overview

Download, purchase, or upload certificates






## Definition

### Public Parameters

| Parameter Name | Type | Description Information | Required |
|:---|:---|:---|:---|
| **Action**     | string  | Corresponding API command name, the current API is `DownloadCertificate`.                      | **Yes** |
| **PublicKey**  | string  | The user's public key can be obtained from [Console](https://console.zosoc.com/uaccount/api_manage)                                             | **Yes** |
| **Signature**  | string  | User signature generated based on public key and API command, see [Signature Algorithm](/docs/api/summary/signature.md)  | **Yes** |

### Request Parameters

| Parameter Name | Type | Description Information | Required |
|:---|:---|:---|:---|
| **CertificateID** | int | Certificate Number |**Yes**|

### Response Field

| Field Name | Type | Description Information | Required |
|:---|:---|:---|:---|
| **RetCode** | int | Return status code. If it is 0, it means successful return. If it is not 0, it means failure. |**Yes**|
| **Action** | string | Operation command name. |**Yes**|
| **Message** | string | Returns an error message, providing detailed description when `RetCode` is non-zero. |No|
| **CertificateUrl** | string | Download path for the certificate |**Yes**|




## Example

### Request Example
    
```
https://api.zosoc.com/?Action=DownloadCertificate
&CertificateID=4
```

### Response Example
    
```json
{
  "Action": "DownloadCertificateResponse",
  "CertificateUrl": "mXDzUQXz",
  "RetCode": 0
}
```