From 92e46194f340164ee1a24b05bb47e01b7fbe25e7 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Fri, 12 May 2023 14:31:03 -0400
Subject: [PATCH] Fix key derivations through "datakey"
* Add direct tests for signature key serialization/deserialization
* Fix the RSA Private Key serializer to use PKCS8 like Tahoe-LAFS expects.
* Fix the key generator to emit keys in this format.
* Fix the key generator to generate 2048 bit keys.
* Fix the derivation functions to make the key values internally consistent.
---
make-keypairs/Main.hs | 18 +++--
src/Tahoe/SDMF/Internal/Keys.hs | 72 +++++++++++++++---
tahoe-ssk.cabal | 1 +
test/Spec.hs | 62 ++++++++++++---
.../data/tahoe-lafs-generated-rsa-privkey.der | Bin 0 -> 1219 bytes
5 files changed, 123 insertions(+), 30 deletions(-)
create mode 100644 test/data/tahoe-lafs-generated-rsa-privkey.der
diff --git a/make-keypairs/Main.hs b/make-keypairs/Main.hs
index d77171e..3e5eea0 100644
--- a/make-keypairs/Main.hs
+++ b/make-keypairs/Main.hs
@@ -1,11 +1,9 @@
module Main where
import qualified Crypto.PubKey.RSA as RSA
-import Data.ASN1.BinaryEncoding (DER (DER))
-import Data.ASN1.Encoding (ASN1Encoding (encodeASN1))
-import Data.ASN1.Types (ASN1Object (toASN1))
-import qualified Data.ByteString.Lazy as LB
-import Data.X509 (PrivKey (PrivKeyRSA))
+import qualified Data.ByteString as B
+import Tahoe.SDMF.Internal.Keys (signatureKeyToBytes)
+import Tahoe.SDMF.Keys (Signature (..))
-- | The size of the keys to generate.
bits :: Int
@@ -21,8 +19,12 @@ main = do
genKey :: Show a => a -> IO ()
genKey n = do
- (_, priv) <- RSA.generate bits e
- let bytes = encodeASN1 DER (toASN1 (PrivKeyRSA priv) [])
- LB.writeFile ("test/data/rsa-privkey-" <> show n <> ".der") bytes
+ print "Generating RSA key..."
+ (_, priv) <- RSA.generate (bits `div` 8) e
+ print $ "Serializing key " <> show n
+ let bytes = signatureKeyToBytes (Signature priv)
+ print $ "Generated them (" <> show (B.length bytes) <> " bytes)"
+ B.writeFile ("test/data/rsa-privkey-" <> show n <> ".der") bytes
+ print "Wrote them to the file."
where
e = 0x10001
diff --git a/src/Tahoe/SDMF/Internal/Keys.hs b/src/Tahoe/SDMF/Internal/Keys.hs
index 40ab740..3478225 100644
--- a/src/Tahoe/SDMF/Internal/Keys.hs
+++ b/src/Tahoe/SDMF/Internal/Keys.hs
@@ -3,14 +3,16 @@ module Tahoe.SDMF.Internal.Keys where
import Prelude hiding (Read)
+import Control.Monad (when)
import Crypto.Cipher.AES (AES128)
import Crypto.Cipher.Types (Cipher (cipherInit, cipherKeySize), IV, KeySizeSpecifier (KeySizeFixed))
import Crypto.Error (maybeCryptoError)
import qualified Crypto.PubKey.RSA as RSA
import Crypto.Random (MonadRandom)
import Data.ASN1.BinaryEncoding (DER (DER))
-import Data.ASN1.Encoding (ASN1Encoding (encodeASN1))
-import Data.ASN1.Types (ASN1Object (toASN1))
+import Data.ASN1.Encoding (ASN1Encoding (encodeASN1), decodeASN1')
+import Data.ASN1.Types (ASN1 (End, IntVal, Null, OID, OctetString, Start), ASN1ConstructionType (Sequence), ASN1Object (fromASN1, toASN1))
+import Data.Bifunctor (Bifunctor (first))
import qualified Data.ByteArray as ByteArray
import qualified Data.ByteString as B
import Data.ByteString.Base32 (encodeBase32Unpadded)
@@ -20,14 +22,19 @@ import Data.X509 (PrivKey (PrivKeyRSA), PubKey (PubKeyRSA))
import Tahoe.CHK.Crypto (taggedHash, taggedPairHash)
import Tahoe.CHK.Server (StorageServerID)
-newtype KeyPair = KeyPair {toPrivateKey :: RSA.PrivateKey}
+newtype KeyPair = KeyPair {toPrivateKey :: RSA.PrivateKey} deriving newtype (Show)
toPublicKey :: KeyPair -> RSA.PublicKey
toPublicKey = RSA.private_pub . toPrivateKey
newtype Verification = Verification {unVerification :: RSA.PublicKey}
newtype Signature = Signature {unSignature :: RSA.PrivateKey}
+ deriving newtype (Eq, Show)
+
data Write = Write {unWrite :: AES128, writeKeyBytes :: ByteArray.ScrubbedBytes}
+instance Show Write where
+ show (Write _ bs) = T.unpack $ T.concat ["<WriteKey ", encodeBase32Unpadded (ByteArray.convert bs), ">"]
+
data Read = Read {unRead :: AES128, readKeyBytes :: ByteArray.ScrubbedBytes}
newtype StorageIndex = StorageIndex {unStorageIndex :: B.ByteString}
@@ -74,10 +81,10 @@ mutableWriteKeyTag = "allmydata_mutable_privkey_to_writekey_v1"
-- | Compute the read key for a given write key for an SDMF share.
deriveReadKey :: Write -> Maybe Read
deriveReadKey w =
- Read <$> key <*> pure sbs
+ Read <$> key <*> pure (ByteArray.convert sbs)
where
- sbs = writeKeyBytes w
- key = maybeCryptoError . cipherInit . taggedHash keyLength mutableReadKeyTag . ByteArray.convert $ sbs
+ sbs = taggedHash keyLength mutableReadKeyTag . ByteArray.convert . writeKeyBytes $ w
+ key = maybeCryptoError . cipherInit $ sbs
mutableReadKeyTag :: B.ByteString
mutableReadKeyTag = "allmydata_mutable_writekey_to_readkey_v1"
@@ -85,10 +92,10 @@ mutableReadKeyTag = "allmydata_mutable_writekey_to_readkey_v1"
-- | Compute the data encryption/decryption key for a given read key for an SDMF share.
deriveDataKey :: SDMF_IV -> Read -> Maybe Data
deriveDataKey (SDMF_IV iv) r =
- Data <$> key <*> pure sbs
+ Data <$> key <*> pure (ByteArray.convert sbs)
where
- sbs = readKeyBytes r
- key = maybeCryptoError . cipherInit . taggedPairHash keyLength mutableDataKeyTag (B.pack . ByteArray.unpack $ iv) . ByteArray.convert $ sbs
+ sbs = B.take keyLength . taggedPairHash keyLength mutableDataKeyTag (B.pack . ByteArray.unpack $ iv) . ByteArray.convert . readKeyBytes $ r
+ key = maybeCryptoError . cipherInit $ sbs
mutableDataKeyTag :: B.ByteString
mutableDataKeyTag = "allmydata_mutable_readkey_to_datakey_v1"
@@ -108,4 +115,49 @@ verificationKeyToBytes = LB.toStrict . encodeASN1 DER . flip toASN1 [] . PubKeyR
PublicKey.
-}
signatureKeyToBytes :: Signature -> B.ByteString
-signatureKeyToBytes = LB.toStrict . encodeASN1 DER . flip toASN1 [] . PrivKeyRSA . unSignature
+signatureKeyToBytes = LB.toStrict . encodeASN1 DER . toPKCS8
+ where
+ -- The ASN1Object instance for PrivKeyRSA can interpret an x509
+ -- "Private-Key Information" (aka PKCS8; see RFC 5208, section 5)
+ -- structure but it _produces_ some other format. We must have exactly
+ -- this format.
+ --
+ -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ --
+ -- RFC 5208 says:
+ --
+ -- privateKey is an octet string whose contents are the value of the
+ -- private key. The interpretation of the contents is defined in the
+ -- registration of the private-key algorithm. For an RSA private key,
+ -- for example, the contents are a BER encoding of a value of type
+ -- RSAPrivateKey.
+ --
+ -- The ASN.1 BER encoding for a given structure is *not guaranteed to be
+ -- unique*. This means that in general there is no guarantee of a unique
+ -- bytes representation of a signature key in this scheme so *key
+ -- derivations are not unique*. If any two implementations disagree on
+ -- this encoding (which BER allows them to do) they will not interoperate.
+ toPKCS8 (Signature privKey) =
+ [ Start Sequence
+ , IntVal 0
+ , Start Sequence
+ , OID [1, 2, 840, 113549, 1, 1, 1]
+ , Null
+ , End Sequence
+ , -- Our ASN.1 encoder doesn't even pretend to support BER. Use DER!
+ -- It results in the same bytes as Tahoe-LAFS is working with so ...
+ -- Maybe we're lucky or maybe Tahoe-LAFS isn't actually following
+ -- the spec.
+ OctetString (LB.toStrict . encodeASN1 DER . toASN1 (PrivKeyRSA privKey) $ [])
+ , End Sequence
+ ]
+
+-- | Decode a private key from the Tahoe-LAFS canonical bytes representation.
+signatureKeyFromBytes :: B.ByteString -> Either String Signature
+signatureKeyFromBytes bs = do
+ asn1s <- first show $ decodeASN1' DER bs
+ (key, extra) <- fromASN1 asn1s
+ when (extra /= []) (Left $ "left over data: " <> show extra)
+ case key of
+ (PrivKeyRSA privKey) -> Right $ Signature privKey
+ _ -> Left ("Expect RSA private key, found " <> show key)
diff --git a/tahoe-ssk.cabal b/tahoe-ssk.cabal
index 2b45eec..d7e3e7b 100644
--- a/tahoe-ssk.cabal
+++ b/tahoe-ssk.cabal
@@ -149,4 +149,5 @@ executable make-keypairs
, base
, bytestring
, cryptonite
+ , tahoe-ssk
, x509
diff --git a/test/Spec.hs b/test/Spec.hs
index 4031d0c..b576ac0 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -9,7 +9,6 @@ import Hedgehog (
import Crypto.Cipher.Types (makeIV)
import Data.ASN1.BinaryEncoding (DER (DER))
import Data.ASN1.Encoding (decodeASN1')
-import Data.ASN1.Types (ASN1Object (fromASN1))
import qualified Data.Binary as Binary
import Data.Binary.Get (ByteOffset)
import qualified Data.ByteArray as ByteArray
@@ -17,10 +16,10 @@ 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 Data.X509 (PrivKey (PrivKeyRSA))
-import Generators (shareHashChains, shares)
+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)
@@ -38,23 +37,62 @@ tests =
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 (Just iv) = Keys.SDMF_IV <$> makeIV (B.replicate 16 0x42)
- expectedWriteKey = ("ae6e6cgcllhty4z5l4dp5v7gee" :: T.Text)
- expectedReadKey = ("rbx5xh5rztefvazy7sq32sw34y" :: T.Text)
- expectedDataKey = ("4ay4y6itvk7cvynpyok3qmxf5y" :: T.Text)
+ let -- Load the test key.
+ (Right sigKey) = signatureKeyFromBytes privBytes
+
+ -- Hard-code the expected result.
+ expectedWriteKey = ("v7iymuxkc5yv2fomi3xwbjdd4e" :: T.Text)
+ expectedReadKey = ("6ir6husgx6ubro3tbimmzskqri" :: T.Text)
+ expectedDataKey = ("bbj67exlrkfcaqutwlgwvukbfe" :: T.Text)
- (Right asn1s) = decodeASN1' DER privBytes
- (Right (PrivKeyRSA privKey, [])) = fromASN1 asn1s
- (Just w@(Keys.Write _ derivedWriteKey)) = Keys.deriveWriteKey (Keys.Signature privKey)
+ -- Derive all the keys.
+ (Just iv) = Keys.SDMF_IV <$> 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
- -- Format a key as text for convenient comparison to
- -- expected value.
+ -- 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
diff --git a/test/data/tahoe-lafs-generated-rsa-privkey.der b/test/data/tahoe-lafs-generated-rsa-privkey.der
new file mode 100644
index 0000000000000000000000000000000000000000..ba71aa1212413a9f581dbc52594ea9fee5338ff0
GIT binary patch
literal 1219
zcmV;!1U&mNf&{+;0RS)!1_>&LNQU<f0RaI800e>rsW5^Br2+u}0)hbn0MkVx)W^`s
zT=ceR<@c+61=VZoh7in0{a?dfh>8lfC!2+YA^WG?@a0j$$&j{td$?FsJyuDZ^ypBS
z_d<`fA)vTFbsh+LTilnwx0wJvc1}B`L=w{6Rx*{Xvr<GN0%q2VrW$dsJofm#J+LPi
z=ocf-Z<VS5@QO_l;$fYR4M9s)rQ`iB+hoC74CvHlHwqbu?G<kUjUhB<vF)Vf3Cye$
zbq`iPxN!BwY_d%Cg^~T~?JOw!3r;Fb%&ff*@hz9^1IB5{F%6X}v9)IEJJ9gvIijp@
zw;+)%?<BY-%5~GMp>M<UAzuI&k*)zRp^I_3>&-ya)ve++DAXlae*yym009Dm0RU6q
zq@GyacuoHh)4)i58TGF2^GEzIJ$*-^W#*{%>#g~|9pLBbl6y#R7bmiP-?S7_Y|s@8
zkPyI<4#-OKh7P--ssFO}rblDq63DK@JEK+?v)a6-UAGd+{dKK*Lk~3wgKokc(~*2~
z@17^>y+HK7&|BC{@1~C-U9v<Hs;j%kZ|uHVVw~NqHm8<*tG9r=8NPT2j!llFj(Z6N
zDt*;hXL*GYcdo;;l@CqWzEA;QRTA`iQg@|~(}ZUK67wwGNc{Kv(FEVR8E)J4`$oz2
zQ0t6VCak_oaLXi>bHpr6d*#(6uSA{>%#xtG;)=9^-p?2%1Knf>b|}}->`?-NfdJ!T
zD76`H;k1RCH`QVqOpyiZGlRb#vvFRYquXVU>=rY%V%h6aT0e0NrSD}5ml{1(K`+hv
zrzekeapehlml&gPoYb+;s$BpO{60MLHLHPB7MC7Rd#OJ>{v7;mr`38Zy*J?EZCmaA
zA3yql=n$%0fO$W5{IPC~q+yh@l+^-(fdK8>)*DM>6vZ0t6b#x3y7y-(saR!WCvD1&
z!mmOElhcpw#BpGciiG4sIC%iSfd<vH&lfbCWw->zj80JL)ep03ObBNED@`i$F^vTI
z9BY&l+Sl5I^F0)9z6f;w9hezdJPySsP_JHGsKbnz<AD78OKhJ8p|sQJ<>fsGwF3fy
zfdJio8YTW0D~3w7#5qWeQIy(j9j)<~7&s7c`!AIzxb%;G+CpcfAp*BP7|gC=xOzy>
zFNi;0FF>o#L%UR!Y6l1XgXZ%kQ_rtv+%8M=t1sG<a_7|$n`Uc4AWmQ0_@zsd8;H2L
z7Rq~a8swQk!_24!-se16%^;AB()x0H+1UbtfdIQ0HoMh&q&2=yNqs77zm+FKZ~!I`
z?oGf8?cFI-tZcVK(MMG((@bEuZSYVOQj2TBIo=5MO81IcQCYC>oi*}oWKJKXcu@qr
z=@|i*X)=A0c#K_0LWBbJaOwICfPTq9%uLzppMbIYw2aK9r+g@a3H$KEsH3tY`QdFg
z2)zP<fdIIO9;3ptIu!}b=K1_W*^taDLn8&)uug3Vyg*$4CsS)}){?gplWZ9jDb70Y
zC*ChB7^Al0S4gh#=*}ZuBY5$KE=gA7&-wzzMLDnBf40dC)V_lL5@IPw0U`3eFt&>q
h0!T<a8YOmx(%~GIK`x8-11ikYSl^kF>b~%MBW9~IRyhCw
literal 0
HcmV?d00001
--
GitLab