PKCS8EncodedKeyReader.scala

package lib

import java.io.InputStream
import java.security.KeyFactory
import java.security.interfaces.{RSAPrivateKey, RSAPublicKey}
import java.security.spec.{PKCS8EncodedKeySpec, X509EncodedKeySpec}

import javax.inject.Inject
import play.api.Environment

/**
  * https://stackoverflow.com/a/19387517/754565
  */
class PKCS8EncodedKeyReader @Inject()(environment: Environment) {

  lazy val kf: KeyFactory = KeyFactory.getInstance("RSA")

  def getPrivateKey(path: String): RSAPrivateKey = {
    val spec = new PKCS8EncodedKeySpec(readKey(path))
    kf.generatePrivate(spec).asInstanceOf[RSAPrivateKey]
  }

  def getPublicKey(path: String): RSAPublicKey = {
    val spec = new X509EncodedKeySpec(readKey(path))
    kf.generatePublic(spec).asInstanceOf[RSAPublicKey]
  }

  private def readKey(path: String) = {
    val is: InputStream = environment.resourceAsStream(path)
      .getOrElse(throw new RuntimeException(s"Could not read file $path"))
    Stream.continually(is.read).takeWhile(_ != -1).map(_.toByte).toArray
  }

}