Spec.hs

module Spec where

import Hedgehog (
    forAll,
    property,
    tripping,
 )

import Crypto.Cipher.Types (makeIV)
import Data.ASN1.BinaryEncoding (DER (DER))
import Data.ASN1.Encoding (decodeASN1')
import qualified Data.Binary as Binary
import Data.Binary.Get (ByteOffset)
import qualified Data.ByteArray as ByteArray
import qualified Data.ByteString as B
import Data.ByteString.Base32 (encodeBase32Unpadded)
import qualified Data.ByteString.Lazy as LB
import qualified Data.Text as T
import Generators (genRSAKeys, shareHashChains, shares)
import System.IO (hSetEncoding, stderr, stdout, utf8)
import Tahoe.SDMF (Share)
import Tahoe.SDMF.Internal.Keys (signatureKeyFromBytes, signatureKeyToBytes)
import qualified Tahoe.SDMF.Keys as Keys
import Test.Tasty (TestTree, defaultMain, testGroup)
import Test.Tasty.HUnit (assertEqual, testCase)
import Test.Tasty.Hedgehog (testProperty)

-- The test suite compares against some hard-coded opaque strings.  These
-- expected values were determined using the expected_values.py program in
-- this directory.

tests :: TestTree
tests =
    testGroup
        "SSK"
        [ testProperty "Hash chain round-trips through bytes" $
            property $ do
                hashChain <- forAll shareHashChains
                tripping hashChain Binary.encode decode'
        , testProperty "Signatures round-trip through signatureKeyToBytes . signatureKeyFromBytes" $
            property $ do
                key <- forAll genRSAKeys
                tripping (Keys.Signature . Keys.toPrivateKey $ key) signatureKeyToBytes signatureKeyFromBytes
        , testCase "Signature byte-serializations round-trip through signatureKeyFromBytes . signatureKeyToBytes" $ do
            let keyPaths =
                    [ -- Check ours
                      "test/data/rsa-privkey-0.der"
                    , "test/data/rsa-privkey-1.der"
                    , "test/data/rsa-privkey-2.der"
                    , "test/data/rsa-privkey-3.der"
                    , "test/data/rsa-privkey-4.der"
                    , -- And one from Tahoe-LAFS
                      "test/data/tahoe-lafs-generated-rsa-privkey.der"
                    ]
                checkSignatureRoundTrip p =
                    B.readFile p >>= \original ->
                        let (Right sigKey) = signatureKeyFromBytes original
                            serialized = signatureKeyToBytes sigKey
                         in do
                                -- They should decode to the same structure.  This
                                -- has the advantage of representing differences a
                                -- little more transparently than the next
                                -- assertion.
                                assertEqual
                                    "decodeASN1 original /= decodeASN1 serialized"
                                    (decodeASN1' DER original)
                                    (decodeASN1' DER serialized)
                                -- Also check the raw bytes in case there
                                -- are different representations of the
                                -- structure possible.  The raw bytes
                                -- matter because we hash them in key
                                -- derivations.
                                assertEqual "original /= serialized" original serialized
            -- Check them all
            mapM_ checkSignatureRoundTrip keyPaths
        , testCase "derived keys equal known-correct values" $
            -- The path is relative to the root of the package, which is where
            -- at least some test runners will run the test process.  If
            B.readFile "test/data/rsa-privkey-0.der" >>= \privBytes ->
                let -- Load the test key.
                    (Right sigKey) = signatureKeyFromBytes privBytes

                    -- Hard-code the expected result.
                    expectedWriteKey = ("v7iymuxkc5yv2fomi3xwbjdd4e" :: T.Text)
                    expectedReadKey = ("6ir6husgx6ubro3tbimmzskqri" :: T.Text)
                    expectedDataKey = ("bbj67exlrkfcaqutwlgwvukbfe" :: T.Text)

                    -- Derive all the keys.
                    (Just iv) = Keys.SDMF_IV <$> makeIV (B.replicate 16 0x42)
                    (Just w@(Keys.Write _ derivedWriteKey)) = Keys.deriveWriteKey sigKey
                    (Just r@(Keys.Read _ derivedReadKey)) = Keys.deriveReadKey w
                    (Just d@(Keys.Data _ derivedDataKey)) = Keys.deriveDataKey iv r

                    -- A helper to format a key as text for convenient
                    -- comparison to expected value.
                    fmtKey = T.toLower . encodeBase32Unpadded . ByteArray.convert
                 in do
                        -- In general it might make more sense to convert expected
                        -- into ScrubbedBytes instead of converting derived into
                        -- ByteString but ScrubbedBytes doesn't have a useful Show
                        -- instance so we go the other way.  We're not worried about
                        -- the safety of these test-only keys anyway.
                        assertEqual
                            "expected writekey /= derived writekey"
                            expectedWriteKey
                            (fmtKey derivedWriteKey)
                        assertEqual
                            "expected readkey /= derived readkey"
                            expectedReadKey
                            (fmtKey derivedReadKey)
                        assertEqual
                            "expected datakey /= derived datakey"
                            expectedDataKey
                            (fmtKey derivedDataKey)
        , testProperty "Share round-trips through bytes" $
            property $ do
                share <- forAll shares
                tripping share Binary.encode decode'
        , testCase "known-correct serialized shares round-trip though Share" $
            mapM_ knownCorrectRoundTrip [0 :: Int .. 9]
        ]

{- | Load a known-correct SDMF bucket and assert that bytes in the slot it
 contains deserializes to a Share and then serializes back to the same bytes
-}
knownCorrectRoundTrip :: Show a => a -> IO ()
knownCorrectRoundTrip n = do
    -- The files are in "bucket" format.  We need to extract the
    -- "slot".  We do so by stripping a prefix and suffix.  To avoid
    -- having to parse the prefix, we assert that the suffix is a
    -- predictable size.
    bucket <- LB.readFile ("test/data/3of10." <> show n)
    let withoutPrefix = LB.drop (32 + 20 + 32 + 8 + 8 + 368) bucket
        dataSize = LB.length withoutPrefix - 4
        shareData = LB.take dataSize withoutPrefix
        suffix = LB.drop dataSize withoutPrefix

    -- Our assumption about the data we're working on...
    assertEqual "Cannot account for extra leases" suffix "\0\0\0\0"

    let decoded = decode' shareData
    let encoded = (Binary.encode :: Share -> LB.ByteString) <$> decoded
    assertEqual "original /= encoded" (Right shareData) encoded

-- | Like `Binary.Binary.decodeOrFail` but only return the decoded value.
decode' :: Binary.Binary b => LB.ByteString -> Either (LB.ByteString, ByteOffset, String) b
decode' = ((\(_, _, a) -> a) <$>) . Binary.decodeOrFail

main :: IO ()
main = do
    -- Hedgehog writes some non-ASCII and the whole test process will die if
    -- it can't be encoded.  Increase the chances that all of the output can
    -- be encoded by forcing the use of UTF-8 (overriding the LANG-based
    -- choice normally made).
    hSetEncoding stdout utf8
    hSetEncoding stderr utf8
    defaultMain tests