title: Add RSA key to Android project in a secure way
body: <p>In my Android project a need to cypher and decypher RSA values.
  I have both private &amp; public RSA keys in *.pem files.
  I have added it to the project but when I  try to create the release apk, lint says:</p>
  
  <blockquote>
    <p>Error:Error: The raw/private_key.pem file seems to be a private key file. Please make sure not to embed this in your APK file. [PackagedPrivateKey]
    Error:Execution failed for task ':app:lintVitalRelease'.</p>
    
    <blockquote>
      <p>Lint found fatal errors while assembling a release target.   To proceed, either fix the issues identified by lint, or modify your
      build script as follows:   ...   android {
            lintOptions {
                checkReleaseBuilds false
                // Or, if you prefer, you can continue to check for errors in release builds,
                // but continue the build even when errors are found:
                abortOnError false
            }   }   ...</p>
    </blockquote>
  </blockquote>
  
  <p>I have tried to find the right way to add the keys to the project without success.</p>
  
  <p>Any help on how to add the keys properly?
  Thanks.</p>