core: optionally encrypt SMP files (#3082)

* core: optionally encrypt SMP files

* encrypt to temp file and rename or remove encryption args if it fails

* fix file encryption error handling

tests/ChatTests/Files.hs

@@ -31,6 +31,7 @@ chatFileTests :: SpecWith FilePath
 chatFileTests = do
   describe "sending and receiving files" $ do
     describe "send and receive file" $ fileTestMatrix2 runTestFileTransfer
+    describe "send file, receive and locally encrypt file" $ fileTestMatrix2 runTestFileTransferEncrypted
     it "send and receive file inline (without accepting)" testInlineFileTransfer
     xit'' "accept inline file transfer, sender cancels during transfer" testAcceptInlineFileSndCancelDuringTransfer
     it "send and receive small file inline (default config)" testSmallInlineFileTransfer
@@ -97,6 +98,37 @@ runTestFileTransfer alice bob = do
   dest <- B.readFile "./tests/tmp/test.pdf"
   dest `shouldBe` src
 
+runTestFileTransferEncrypted :: HasCallStack => TestCC -> TestCC -> IO ()
+runTestFileTransferEncrypted alice bob = do
+  connectUsers alice bob
+  alice #> "/f @bob ./tests/fixtures/test.pdf"
+  alice <## "use /fc 1 to cancel sending"
+  bob <# "alice> sends file test.pdf (266.0 KiB / 272376 bytes)"
+  bob <## "use /fr 1 [<dir>/ | <path>] to receive it"
+  bob ##> "/fr 1 encrypt=on ./tests/tmp"
+  bob <## "saving file 1 from alice to ./tests/tmp/test.pdf"
+  Just (CFArgs key nonce) <- J.decode . LB.pack <$> getTermLine bob
+  concurrently_
+    (bob <## "started receiving file 1 (test.pdf) from alice")
+    (alice <## "started sending file 1 (test.pdf) to bob")
+
+  concurrentlyN_
+    [ do
+        bob #> "@alice receiving here..."
+        -- uncomment this and below to test encryption error in encryptFile
+        -- bob <## "cannot write file ./tests/tmp/test.pdf: test error, received file not encrypted"
+        bob <## "completed receiving file 1 (test.pdf) from alice",
+      alice
+        <### [ WithTime "bob> receiving here...",
+               "completed sending file 1 (test.pdf) to bob"
+             ]
+    ]
+  src <- B.readFile "./tests/fixtures/test.pdf"
+  -- dest <- B.readFile "./tests/tmp/test.pdf"
+  -- dest `shouldBe` src
+  Right dest <- chatReadFile "./tests/tmp/test.pdf" (strEncode key) (strEncode nonce)
+  LB.toStrict dest `shouldBe` src
+
 testInlineFileTransfer :: HasCallStack => FilePath -> IO ()
 testInlineFileTransfer =
   testChatCfg2 cfg aliceProfile bobProfile $ \alice bob -> do