title: Serverless: Handle API key decryption in a lambda function
body: <p>I am implementing an API that uses a third party library.</p>
  
  <p>The third party library provides a key which needs to be passed in as an input. The key is dynamic and can change based on consumer/business scenario. The lambda function should be able to decrypt the key.</p>
  
  <p>Can someone suggest a way to decrypt a key? I am exploring aws-kms approach on the side.</p>
  
  <p>Please note: i have noted down the .env way of achieving it. But, today my API is being consumed by one consumer hence one API key. Tomorrow, the number will increase (would result into multiple keys) and i may not be in place to store/update the function. </p>
  
  <p><strong>Edit:</strong> I need to pass some sensitive information through payload. This can be an alphanumeric value. e.g. 
  {"sender": "+123", "secret": "encrypted_value"}
  The client and server should share a key using which client can encrypt the info and server (lambda function) should decrypt it.</p>
  
  <p>Any suggestion would be great! Thanks!</p>