com.dwolla.security.crypto.DecryptToInputStream.scala Maven / Gradle / Ivy

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fs2 pipes for encrypting and decrypting streams with BouncyCastle PGP 1.71
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package com.dwolla.security.crypto

import cats._
import cats.effect._
import cats.syntax.all._
import fs2._
import org.bouncycastle.openpgp._
import org.bouncycastle.openpgp.operator.bc.{BcPBESecretKeyDecryptorBuilder, BcPGPDigestCalculatorProvider, BcPublicKeyDataDecryptorFactory}
import org.typelevel.log4cats.{Logger, LoggerFactory, LoggerName}

import java.io.InputStream
import scala.jdk.CollectionConverters._

private[crypto] sealed trait DecryptToInputStream[F[_], A] {
  def decryptToInputStream(input: A, maybeKeyId: Option[Long])
                          (pbed: PGPPublicKeyEncryptedData): F[InputStream]

  def hasKeyId(input: A, id: Long): Boolean
}

private[crypto] object DecryptToInputStream {
  @inline final def apply[F[_], A](implicit DTIS: DecryptToInputStream[F, A]): DTIS.type = DTIS

  private def attemptDecrypt[F[_] : Sync](pbed: PGPPublicKeyEncryptedData,
                                          factory: BcPublicKeyDataDecryptorFactory): F[InputStream] =
    Sync[F].blocking {
      pbed.getDataStream(factory)
    }

  /**
   * Tries to decrypt the `PGPPublicKeyEncryptedData` using each secret key in the given list of keys.
   * The first key that doesn't throw an exception when doing `pbed.getDataStream` will be the one
   * whose `InputStream` is read downstream. Once it finds a key that works, it will stop trying
   * any subsequent keys.
   */
  private def decryptWithKeys[F[_] : Sync : Logger](input: List[PGPSecretKey],
                                                    passphrase: Array[Char],
                                                    pbed: PGPPublicKeyEncryptedData,
                                                    keyId: Option[Long],
                                                   ): F[InputStream] =
    Stream
      .emits(input)
      .evalMap { secretKey =>
        Sync[F].blocking {
          val digestCalculatorProvider = new BcPGPDigestCalculatorProvider()
          val decryptor = new BcPBESecretKeyDecryptorBuilder(digestCalculatorProvider).build(passphrase)
          val key = secretKey.extractPrivateKey(decryptor)
          secretKey -> new BcPublicKeyDataDecryptorFactory(key)
        }
      }
      .evalMap { case (key, decryptorFactory) =>
        attemptDecrypt(pbed, decryptorFactory)
          .map(_.some)
          .handleErrorWith {
            case t if keyId.contains(key.getKeyID) =>
              Logger[F].trace(t)(s"an error occurred decrypting with what appears to be the correct key ID (${key.getKeyID}); ignoring and attempting to continue").as(None)
            case _ =>
              none.pure[F]
          }
      }
      .unNone
      .head
      .compile
      .lastOrError
      .adaptErr {
        case _: NoSuchElementException => KeyRingMissingKeyException(keyId)
      }

  implicit def PGPSecretKeyRingCollectionInstance[F[_] : Sync : LoggerFactory]: DecryptToInputStream[F, (PGPSecretKeyRingCollection, Array[Char])] =
    new DecryptToInputStream[F, (PGPSecretKeyRingCollection, Array[Char])] {

      override def hasKeyId(input: (PGPSecretKeyRingCollection, Array[Char]), id: Long): Boolean =
        input._1.contains(id)

      override def decryptToInputStream(input: (PGPSecretKeyRingCollection, Array[Char]),
                                        maybeKeyId: Option[Long])
                                       (pbed: PGPPublicKeyEncryptedData): F[InputStream] =
        LoggerFactory[F]
          .create(LoggerName("com.dwolla.security.crypto.DecryptToInputStream.PGPSecretKeyRingCollectionInstance"))
          .flatMap { implicit logger =>
            maybeKeyId
              .toOptionT
              .flatMapF { keyId =>
                ApplicativeThrow[F].catchNonFatal {
                  Option(input._1.getSecretKey(keyId))
                }
              }
              .map(_.pure[List])
              .getOrElse(input._1.getKeyRings.asScala.toList.flatMap(_.getSecretKeys.asScala))
              .flatMap(decryptWithKeys(_, input._2, pbed, maybeKeyId))
          }
    }

  implicit def PGPSecretKeyRingInstance[F[_] : Sync : LoggerFactory]: DecryptToInputStream[F, (PGPSecretKeyRing, Array[Char])] =
    new DecryptToInputStream[F, (PGPSecretKeyRing, Array[Char])] {
      override def hasKeyId(input: (PGPSecretKeyRing, Array[Char]), id: Long): Boolean =
        input
          ._1
          .getSecretKeys
          .asScala
          .exists(_.getKeyID == id)

      override def decryptToInputStream(input: (PGPSecretKeyRing, Array[Char]),
                                        maybeKeyId: Option[Long])
                                       (pbed: PGPPublicKeyEncryptedData): F[InputStream] = {
        val keys = maybeKeyId.fold(input._1.getSecretKeys.asScala.toList) { keyId =>
          Option(input._1.getSecretKey(keyId)).toList
        }

        LoggerFactory[F]
          .create(LoggerName("com.dwolla.security.crypto.DecryptToInputStream.PGPSecretKeyRingCollectionInstance"))
          .flatMap { implicit logger =>
            decryptWithKeys(keys, input._2, pbed, maybeKeyId)
          }
      }
    }

  implicit def PGPPrivateKeyInstance[F[_] : Sync]: DecryptToInputStream[F, PGPPrivateKey] =
    new DecryptToInputStream[F, PGPPrivateKey] {
      override def hasKeyId(input: PGPPrivateKey, id: Long): Boolean =
        input.getKeyID == id

      override def decryptToInputStream(input: PGPPrivateKey,
                                        maybeKeyId: Option[Long])
                                       (pbed: PGPPublicKeyEncryptedData): F[InputStream] =
        if (maybeKeyId.exists(_ != input.getKeyID)) KeyMismatchException(maybeKeyId, input.getKeyID).raiseError
        else
          Sync[F].blocking(new BcPublicKeyDataDecryptorFactory(input))
            .flatMap(attemptDecrypt(pbed, _))
    }

  implicit def toPGPPublicKeyEncryptedDataOps(pbed: PGPPublicKeyEncryptedData): PGPPublicKeyEncryptedDataOps = new PGPPublicKeyEncryptedDataOps(pbed)
}

class PGPPublicKeyEncryptedDataOps(val pbed: PGPPublicKeyEncryptedData) extends AnyVal {
  def decryptToInputStream[F[_], A](input: A, maybeKeyId: Option[Long])
                                   (implicit D: DecryptToInputStream[F, A]): F[InputStream] =
    DecryptToInputStream[F, A].decryptToInputStream(input, maybeKeyId)(pbed)
}