title: How secure is using the /tmp directory in an AWS lambda?
body: <p>I've been looking at implementing the <code>aws_encryption_sdk</code> in a lambda to deal with encrypted files that are uploaded into a s3 bucket.</p>
  
  <p>I have been able to get it to work by downloading the file into the <code>/tmp</code> directory (giving the file a unique name), decrypting the file in the same directory and then uploading the decrypted file back into s3.  I am also deleting the files in the system after the operation has completed, but before exiting the lambda</p>
  
  <p>While using the file system is common use case, I have concerns around the use of the <code>/tmp</code> directory and its security.</p>
  
  <p>Can anyone advise whether I should be concerned?  How exclusive is the file system when you fire up Lambdas?</p>
  
  <p>Thanks</p>