POST {base_url}/api/ess/get-latest-channel-token
Authorization: MC {accesskKey}:{Base64 encoded signed Data To Sign}
x-mc-date: {dateTime}
x-mc-req-id: {unique id}
x-mc-app-id: {applicationId}
Content-Type: application/json
Accept: application/json
 
{
  "data": [
    {
      "channelId": "B8Y43U-GYVS-WHAU6M"
    }
  ]
}

import base64
import hashlib
import hmac
import uuid
import datetime
import requests
 
# Setup required variables
base_url = "https://xx-api.mimecast.com"
uri = "/api/ess/get-latest-channel-token"
url = base_url + uri
access_key = "YOUR ACCESS KEY"
secret_key = "YOUR SECRET KEY"
app_id = "YOUR APPLICATION ID"
app_key = "YOUR APPLICATION KEY"
 
# Generate request header values
request_id = str(uuid.uuid4())
hdr_date = datetime.datetime.utcnow().strftime("%a, %d %b %Y %H:%M:%S") + " UTC"
 
# DataToSign is used in hmac_sha1
dataToSign = ':'.join([hdr_date, request_id, uri, app_key])
 
# Create the HMAC SHA1 of the Base64 decoded secret key for the Authorization header
hmac_sha1 = hmac.new(base64.b64decode(secret_key), dataToSign.encode(), digestmod=hashlib.sha1).digest()
 
# Use the HMAC SHA1 value to sign the hdrDate + ":" requestId + ":" + URI + ":" + appkey
sig = base64.b64encode(hmac_sha1).rstrip()
 
# Create request headers
headers = {
    'Authorization': 'MC ' + access_key + ':' + sig.decode(),
    'x-mc-app-id': app_id,
    'x-mc-date': hdr_date,
    'x-mc-req-id': request_id,
    'Content-Type': 'application/json'
}
 
payload = {
  'data': [
    {
      'channelId': 'B8Y43U-GYVS-WHAU6M'
    }
  ]
}
 
r = requests.post(url=url, headers=headers, data=str(payload))
 
print(r.text)

static void Main(string[] args)
        {
            //Setup required variables
            string baseUrl = "https://xx-api.mimecast.com";
            string uri = "/api/ess/get-latest-channel-token";
            string accessKey = "YOUR ACCESS KEY";
            string secretKey = "YOUR SECRET KEY";
            string appId = "YOUR APPLICATION ID";
            string appKey = "YOUR APPLICATION KEY";
 
            //Generate request header values
            string hdrDate = System.DateTime.Now.ToUniversalTime().ToString("R");
            string requestId = System.Guid.NewGuid().ToString();
 
            //Create the HMAC SHA1 of the Base64 decoded secret key for the Authorization header
            System.Security.Cryptography.HMAC h = new System.Security.Cryptography.HMACSHA1(System.Convert.FromBase64String(secretKey));
 
            //Use the HMAC SHA1 value to sign the hdrDate + ":" requestId + ":" + URI + ":" + appkey
            byte[] hash = h.ComputeHash(System.Text.Encoding.Default.GetBytes(hdrDate + ":" + requestId + ":" + uri + ":" + appKey));
 
            //Build the signature to be included in the Authorization header in your request
            string signature = "MC " + accessKey + ":" + System.Convert.ToBase64String(hash);
 
            //Build Request
            System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(baseUrl + uri);
            request.Method = "POST";
            request.ContentType = "application/json";
 
            //Add Headers
            request.Headers[System.Net.HttpRequestHeader.Authorization] = signature;
            request.Headers.Add("x-mc-date", hdrDate);
            request.Headers.Add("x-mc-req-id", requestId);
            request.Headers.Add("x-mc-app-id", appId);
 
            //Add request body
            //Create and write data to stream
            string postData = @"{
  ""data"": [
    {
      ""channelId"": ""B8Y43U-GYVS-WHAU6M""
    }
  ]
}";
 
            byte[] payload = System.Text.Encoding.UTF8.GetBytes(postData);
 
            System.IO.Stream stream = request.GetRequestStream();
            stream.Write(payload, 0, payload.Length);
            stream.Close();
 
            //Send Request
            System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
 
            //Output response to console
            System.IO.StreamReader reader = new System.IO.StreamReader(response.GetResponseStream());
            string responseBody = "";
            string temp = null;
            while ((temp = reader.ReadLine()) != null)
            {
                responseBody += temp;
            };
            System.Console.WriteLine(responseBody);
            System.Console.ReadLine();
        }

#Setup required variables
$baseUrl = "https://xx-api.mimecast.com"
$uri = "/api/ess/get-latest-channel-token"
$url = $baseUrl + $uri
$accessKey = "YOUR ACCESS KEY"
$secretKey = "YOUR SECRET KEY"
$appId = "YOUR APPLICATION ID"
$appKey = "YOUR APPLICATION KEY"
 
#Generate request header values
$hdrDate = (Get-Date).ToUniversalTime().ToString("ddd, dd MMM yyyy HH:mm:ss UTC")
$requestId = [guid]::NewGuid().guid
 
#Create the HMAC SHA1 of the Base64 decoded secret key for the Authorization header
$sha = New-Object System.Security.Cryptography.HMACSHA1
$sha.key = [Convert]::FromBase64String($secretKey)
$sig = $sha.ComputeHash([Text.Encoding]::UTF8.GetBytes($hdrDate + ":" + $requestId + ":" + $uri + ":" + $appKey))
$sig = [Convert]::ToBase64String($sig)
 
#Create Headers
$headers = @{"Authorization" = "MC " + $accessKey + ":" + $sig;
                "x-mc-date" = $hdrDate;
                "x-mc-app-id" = $appId;
                "x-mc-req-id" = $requestId;
                "Content-Type" = "application/json"}
 
#Create post body
$postBody = "{
  ""data"": [
    {
      ""channelId"": ""B8Y43U-GYVS-WHAU6M""
    }
  ]
}"
 
#Send Request
$response = Invoke-RestMethod -Method Post -Headers $headers -Body $postBody -Uri $url
 
#Print the response
$response

public static void main(String[] args) throws java.io.IOException, java.security.NoSuchAlgorithmException, java.security.InvalidKeyException {
 
        //set up variables for request
        String baseUrl = "https://xx-api.mimecast.com";
        String uri = "/api/ess/get-latest-channel-token";
        String url = "https://" + baseUrl + uri;
        String accessKey = "YOUR ACCESS KEY";
        String secretKey = "YOUR SECRET KEY";
        String appId = "YOUR APPLICATION ID";
        String appKey = "YOUR APPLICATION KEY";
 
        //create URL object
        java.net.URL obj = new java.net.URL(url);
 
        // set guid for x-mc-req-id header
        String guid = java.util.UUID.randomUUID().toString();
 
        // set date for x-mc-date header
        java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss z");
        sdf.setTimeZone(java.util.TimeZone.getTimeZone("UTC"));
        String date = sdf.format(new java.util.Date());
 
        //create signature for the Authorization header
        String dataToSign = date + ":" + guid + ":" + uri + ":" + appKey;
        String hmacSHA1 = "HmacSHA1";
        javax.crypto.spec.SecretKeySpec signingKey = new javax.crypto.spec.SecretKeySpec(org.apache.commons.codec.binary.Base64.decodeBase64(secretKey.getBytes()), hmacSHA1);
        javax.crypto.Mac mac = javax.crypto.Mac.getInstance(hmacSHA1);
        mac.init(signingKey);
        String sig = new String(org.apache.commons.codec.binary.Base64.encodeBase64(mac.doFinal(dataToSign.getBytes())));
 
        // create request object
        javax.net.ssl.HttpsURLConnection con = (javax.net.ssl.HttpsURLConnection) obj.openConnection();
 
        //set request type to POST
        con.setRequestMethod("POST");
        con.setDoOutput(true);
 
        //add reuqest headers
        con.setRequestProperty("Authorization", "MC " + accessKey + ":" + sig);
        con.setRequestProperty("x-mc-req-id", guid);
        con.setRequestProperty("x-mc-app-id", appId);
        con.setRequestProperty("x-mc-date", date);
        con.setRequestProperty("Content-Type", "application/json");
        con.setRequestProperty("Accept", "application/json");
 
        //Add post body to the request
        String postBody = "{\n" +
"  \"data\": [\n" +
"    {\n" +
"      \"channelId\": \"B8Y43U-GYVS-WHAU6M\"\n" +
"    }\n" +
"  ]\n" +
"}";
        java.io.OutputStream os = con.getOutputStream();
        os.write(postBody.getBytes("UTF-8"));
        os.close();
 
        //process response
        java.io.BufferedReader in = new java.io.BufferedReader(
                new java.io.InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
 
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
 
        //return result
        java.lang.System.out.println(response.toString());
    }