AWS Lambda Functions

Create Lambda function

Go to AWS Lambda homepage and login to console.
Press "Create Function" button.
Enter function name.
Select a language (environment) from Runtime dropdown. I will use node.js 8.10.

For the first time you can create a new role for permissions. Select "Create a custom role" from Role dropdown box.
A new page will be shown. Select "Create a new IAM Role" from IMA Role dropdown and then give a name. Press "Allow" button.

This will create a new role and browser will return back to "Create function" page.
Press "Create function" button.
It will redirect you to function page.

Initially the page adds a template code which returns success code and a hello message. We will continue with this code.

 

exports.handler = async (event) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

2. AWS CLI to call the function

Download AWS CLI setup to your computer. For Windows download link is here. For other operating systems you can find links at the same page.
After installation go to aws cli folder and run following command to start configuration.

aws configure

We need following info.

AWS Access Key ID [None]: "Your Access Key"
AWS Secret Access Key [None]: "Your Secret Key"
Default region name [None]: 
Default output format [None]: 

To get keys go to AWS console
Click to your name and select "My Security Credentials".

On "Access keys" section click to "Create New Access Key" button to create new keys. You have to save your secret key because it will displayed only once.

Now return back to aws cli console and enter Access Key ID and Secret Access Key.
Enter region name like "us-west-2".
Enter json for default output format.
Now you can run your functions.
We need our function name as a parameter. In lambda function page copy arn.

Run aws command to run function. The lines between "{ }" is the response from our lambda function. You can see hello message inside txt file which we passed as a parameter.

aws lambda invoke --function-name arn:aws:lambda:us-west-2:123456780315:function:FirstLambda "c:\aws.txt"

{
    "StatusCode": 200,
    "ExecutedVersion": "$LATEST"
}

aws.txt file content

{"statusCode":200,"body":"\"Hello from Lambda!\""}

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Decryption function (dotnet & nodejs)

In "Encryption function (dotnet & nodejs)" post I described encryption functions.
In this post you can see decrypt functions.

Nodejs uses "crypto-js" package.
Dotnet uses "System.Security.Cryptography" namespace.

Dotnet

 

public static string Decrypt(string encryptedBase64)
{
 byte[] rawSecretKey = { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 };  
 string PassPhrase = "passPhrase";

 MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
 byte[] data = Encoding.ASCII.GetBytes(PassPhrase);
 data.Dump("data");
 
 byte[] passwordKey = x.ComputeHash(data);
 
 RijndaelManaged rijndael = new RijndaelManaged();
 ICryptoTransform rijndaelDecryptor = rijndael.CreateDecryptor(passwordKey, rawSecretKey);
 try
 {
  byte[] encryptedData = Convert.FromBase64String(encryptedBase64);
  byte[] newClearData = rijndaelDecryptor.TransformFinalBlock(encryptedData, 0, encryptedData.Length);
  return Encoding.ASCII.GetString(newClearData);
 }
 catch (Exception ex)
 {
  return null;
 }
}

Node.js

 

 var bytes = CryptoJS.AES.decrypt(encrypted, myRijndaelKey, {
        iv: ivCodeWords,
        mode: CryptoJS.mode.CBC,
        padding: CryptoJS.pad.Pkcs7
    });
 var plaintext = bytes.toString(CryptoJS.enc.Utf8);
 console.log("decrypted text: " + plaintext);

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Encryption function (dotnet & nodejs)

Following functions give same result on dotnet and nodejs platforms.
Nodejs uses "crypto-js" package.
Dotnet uses "System.Security.Cryptography" namespace.

Dotnet

void Main()  
 {  
     string clearText = "oktay";  
     Console.WriteLine("clearText: " + clearText);  
     string encrypted = Crypto.EncryptToBase64(clearText);  
     Console.WriteLine("encrypted: " + encrypted);  
 }  
 public static class Crypto  
 {  
   public static string EncryptToBase64(string decryptedText)  
   {  
     byte[] rawSecretKey = { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 };  
     string PassPhrase = "passPhrase";  
     MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();  
     byte[] data = Encoding.UTF8.GetBytes(PassPhrase);  
         byte[] passwordKey = x.ComputeHash(data);  
         Console.WriteLine("key: " + BitConverter.ToString(passwordKey).Replace("-", ""));  
         Console.WriteLine("iv : " + BitConverter.ToString(rawSecretKey).Replace("-", ""));  
         RijndaelManaged rijndael = new RijndaelManaged();  
     ICryptoTransform rijndaelEncryptor = rijndael.CreateEncryptor(passwordKey, rawSecretKey);  
     try  
     {  
       byte[] decryptedData = Encoding.UTF8.GetBytes(decryptedText);  
       byte[] newClearData = rijndaelEncryptor.TransformFinalBlock(decryptedData, 0, decryptedData.Length);  
       return Convert.ToBase64String(newClearData, 0, newClearData.Length);  
     }  
     catch (Exception ex)  
     {  
       throw ex;  
     }  
   }  
 }  

Node.js

 
 var CryptoJS = require("crypto-js");  
 function byteArrayToHexString(byteArray) {  
  return Array.prototype.map  
   .call(byteArray, function(byte) {  
    return ("0" + (byte & 0xff).toString(16)).slice(-2);  
   })  
   .join("");  
 }  

 function EncryptToBase64(password) {
  console.log("clearText: " + password); 
  var PassPhrase = "passPhrase";  
  var rawSecretKey = [ 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 ];
  
  var myRijndaelKeyBytes = CryptoJS.enc.Utf8.parse(PassPhrase);  
  var myRijndaelKey = CryptoJS.MD5(CryptoJS.enc.Utf8.parse(PassPhrase));  
  console.log("key: " + myRijndaelKey);  
  var myRijndaelIV = byteArrayToHexString(rawSecretKey);  
  var ivCodeWords = CryptoJS.enc.Hex.parse(myRijndaelIV);  
  console.log("iv: " + ivCodeWords);  
  var encrypted = CryptoJS.AES.encrypt(  
   CryptoJS.enc.Utf8.parse(password),  
   myRijndaelKey,  
   {  
    iv: ivCodeWords,  
    mode: CryptoJS.mode.CBC,  
    padding: CryptoJS.pad.Pkcs7  
   }  
  );  
  var base64 = CryptoJS.enc.Base64.stringify(encrypted.ciphertext);  
  console.log("encrypted: " + base64);  
 }  
 EncryptToBase64("oktay");  
 return;  

Result

clearText: oktay
key: C6CEC8C6CAA9A579644664F0575DB2F5
iv : 01010101010101010101010101010101
encrypted: S+6CSoMM6no9atihmfyayQ==

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