diff --git a/hjugement-cli.cabal b/hjugement-cli.cabal
--- a/hjugement-cli.cabal
+++ b/hjugement-cli.cabal
@@ -2,7 +2,7 @@
 -- PVP:  +-+------- breaking API changes
 --       | | +----- non-breaking API additions
 --       | | | +--- code changes with no API change
-version: 0.0.0.20190815
+version: 0.0.0.20191028
 category: Politic
 synopsis: Majority Judgment and Helios-C command line tool
 description:
@@ -74,7 +74,7 @@
     -- -fhide-source-paths
   build-depends:
       hjugement >= 2.0.2
-    , hjugement-protocol >= 0.0.7
+    , hjugement-protocol >= 0.0.8
     , aeson >= 1.3
     , base >= 4.6 && < 5
     , base64-bytestring >= 1.0
@@ -98,7 +98,7 @@
     , random >= 1.1
     , reflection >= 2.1
     , symantic-cli >= 2.4.2
-    , symantic-document >= 1.5
+    , symantic-document >= 1.5.1
     , terminal-size >= 0.3
     , text >= 1.2
     , time >= 1.8
diff --git a/src/Hjugement/CLI/Administrator.hs b/src/Hjugement/CLI/Administrator.hs
--- a/src/Hjugement/CLI/Administrator.hs
+++ b/src/Hjugement/CLI/Administrator.hs
@@ -59,6 +59,7 @@
  ,   administratorElection_uuid         :: Maybe Text
  ,   administratorElection_grades       :: [Text]
  ,   administratorElection_defaultGrade :: Maybe Text
+ ,   administratorElection_version      :: VP.Version
  } deriving (Show)
 
 api_administrator_election =
@@ -75,7 +76,8 @@
 			 <*> api_param_description
 			 <*> api_option_uuid
 			 <*> api_param_grades
-			 <*> api_param_defaultGrade)
+			 <*> api_param_defaultGrade
+			 <*> api_param_version)
 		<?> api_quests
 		<.> response @(Maybe ())
 	where
@@ -112,7 +114,8 @@
  glob@Global_Params{..}
  AdministratorElection_Params{..}
  quests =
-	VP.reify administratorElection_crypto $ \(_crypto::Proxy c) -> runMaybeT $ do
+	VP.reify administratorElection_version $ \(_v::Proxy v) ->
+	VP.reify administratorElection_crypto $ \(_c::Proxy c) -> runMaybeT $ do
 		election_uuid <-
 			case administratorElection_uuid of
 			 Nothing -> Pip.liftIO $ Rand.getStdRandom $ runState $ VP.randomUUID
@@ -121,7 +124,7 @@
 				 Left err -> outputError glob $ Doc.from (show err)
 				 Right uuid -> return uuid
 		let trusteeKeysPath = global_dir FP.</> "public_keys.jsons"
-		trusteeKeys :: [VP.TrusteePublicKey c] <- runPipeWithError glob $
+		trusteeKeys :: [VP.TrusteePublicKey VP.FFC v c] <- runPipeWithError glob $
 			Pip.toListM' $ readJSON glob trusteeKeysPath
 		forM_ trusteeKeys $ \trusteeKey ->
 			case runExcept $ VP.verifyIndispensableTrusteePublicKey trusteeKey of
@@ -138,22 +141,21 @@
 			fromMaybe (grades List.!!0)
 			 administratorElection_defaultGrade
 		 -- FIXME: put defaultGrade into election.json
-		let elec =
+		let elec :: VP.Election VP.FFC v c =
 			VP.Election
 			 { VP.election_name        = administratorElection_name
 			 , VP.election_description = administratorElection_description
-			 , VP.election_crypto      = VP.ElectionCrypto_FFC
-				 { electionCrypto_FFC_params    = administratorElection_crypto
-				 , electionCrypto_FFC_PublicKey = VP.combineIndispensableTrusteePublicKeys trusteeKeys
-				 }
-			 , VP.election_questions = (<$> quests) $ \quest -> VP.Question
+			 , VP.election_crypto      = administratorElection_crypto
+			 , VP.election_public_key  = VP.combineIndispensableTrusteePublicKeys trusteeKeys
+			 , VP.election_questions   = (<$> quests) $ \quest -> VP.Question
 				 { question_text    = quest
 				 , question_choices = grades
 				 , question_mini    = 1
 				 , question_maxi    = 1
 				 }
 			 , VP.election_uuid
-			 , VP.election_hash = VP.Base64SHA256 ""
+			 , VP.election_version = Just administratorElection_version
+			 , VP.election_hash    = VP.hashElection elec
 			 }
 		saveJSON glob (global_dir FP.</> "election.json") elec
 		outputInfo glob $
@@ -173,8 +175,8 @@
 
 run_administrator_tally
  glob@Global_Params{..} = runMaybeT $ do
-	rawElec <- loadElection glob $ global_dir FP.</> "election.json"
-	VP.reifyElection rawElec $ \(_elec :: VP.Election c) -> do
+	loadElection glob (global_dir FP.</> "election.json") $
+	 \(_elec :: VP.Election VP.FFC v c) -> do
 		keys <- runPipeWithError glob $ Pip.toListM' $
 			readJSON glob $ global_dir FP.</> "public_keys.jsons"
 		decs <- runPipeWithError glob $ Pip.toListM' $
@@ -187,7 +189,7 @@
 				readJSON glob $ global_dir FP.</> "ballots.jsons"
 		outputInfo glob $ "decrypting tally using trustees' decryption shares"
 		case runExcept $ VP.proveTally
-			 (encTally :: VP.EncryptedTally c, numBallots) decs
+			 (encTally :: VP.EncryptedTally VP.FFC v c, numBallots) decs
 			 (VP.combineIndispensableDecryptionShares (VP.trustee_PublicKey <$> keys)) of
 		 Left err -> outputError glob $ Doc.from (show err)
 		 Right tally -> do
diff --git a/src/Hjugement/CLI/Registrar.hs b/src/Hjugement/CLI/Registrar.hs
--- a/src/Hjugement/CLI/Registrar.hs
+++ b/src/Hjugement/CLI/Registrar.hs
@@ -44,8 +44,9 @@
 
 -- ** Type 'Registrar_Params'
 data Registrar_Params = Registrar_Params
- {   registrar_election_crypto :: VP.FFC
- ,   registrar_election_uuid   :: VP.UUID
+ {   registrar_election_crypto  :: VP.FFC
+ ,   registrar_election_version :: VP.Version
+ ,   registrar_election_uuid    :: VP.UUID
  } deriving (Show)
 
 api_registrar =
@@ -55,6 +56,7 @@
 		rule "PARAMS"
 		 (Registrar_Params
 			 <$> api_param_crypto
+			 <*> api_param_version
 			 <*> api_param_uuid)
 		<?> (
 			api_registrar_credentials <!>
@@ -80,7 +82,7 @@
 	return $
 		VP.reify registrar_election_crypto $ \(_::Proxy c) ->
 			VP.nat $ VP.publicKey $
-				VP.credentialSecretKey @c registrar_election_uuid cred
+				VP.credentialSecretKey @VP.FFC @c registrar_election_uuid cred
 
 api_registrar_credentials =
 	"Generate voters' credentials, either "<>ref "COUNT"<>" sequential identities\
@@ -148,7 +150,7 @@
 						 >-> writeFileLn glob 0o400 (baseFile FP.<.>"privcreds")
 					 )
 					 >-> Pip.mapM (\(ident, cred) ->
-						let secKey = VP.credentialSecretKey @c registrar_election_uuid cred in
+						let secKey = VP.credentialSecretKey @VP.FFC @c registrar_election_uuid cred in
 						let pubKey = VP.publicKey secKey in
 						return (ident, pubKey))
 					 >-> Pip.tee (
diff --git a/src/Hjugement/CLI/Trustee.hs b/src/Hjugement/CLI/Trustee.hs
--- a/src/Hjugement/CLI/Trustee.hs
+++ b/src/Hjugement/CLI/Trustee.hs
@@ -36,7 +36,8 @@
 
 -- * trustee
 data Trustee_Params = Trustee_Params
- { trustee_crypto :: VP.FFC
+ { trustee_crypto  :: VP.FFC
+ , trustee_version :: VP.Version
  } deriving (Show)
 
 api_trustee =
@@ -46,6 +47,7 @@
 		rule "TrusteeParams"
 		 (Trustee_Params
 			 <$> api_param_crypto
+			 <*> api_param_version
 		 ) <?> (
 			api_trustee_generate <!>
 			api_trustee_decrypt
@@ -75,10 +77,12 @@
 run_trustee_generate
  glob@Global_Params{..}
  Trustee_Params{..} =
-	VP.reify trustee_crypto $ \(_crypto::Proxy c) -> do
+	VP.reify trustee_version $ \(_v::Proxy v) -> do
+	VP.reify trustee_crypto $ \(_c::Proxy c) -> do
 		(secKey, pubKey) <- Pip.liftIO $ Rand.getStdRandom $ runState $ do
-			secKey <- VP.randomSecretKey @c
-			pubKey <- VP.proveIndispensableTrusteePublicKey secKey
+			secKey <- VP.randomSecretKey @VP.FFC @c
+			pubKey :: VP.TrusteePublicKey VP.FFC v c
+			 <- VP.proveIndispensableTrusteePublicKey secKey
 			return (secKey, pubKey)
 		let pubIdent =
 			T.unpack $ T.toUpper $ T.take 8 $
@@ -108,7 +112,7 @@
 		 (TrusteeDecrypt_Params
 			 <$> api_param_privkey
 			 <*> api_param_url)
-		<?> response @(Maybe (VP.DecryptionShare ()))
+		<?> response @(Maybe (VP.DecryptionShare VP.FFC () ()))
 	where
 	api_param_privkey =
 		"Read private key from file "<>ref"FILE"<>"."
@@ -119,8 +123,9 @@
  glob@Global_Params{..}
  Trustee_Params{..}
  TrusteeDecrypt_Params{..} =
+	VP.reify trustee_version $ \(_v::Proxy v) -> do
 	VP.reify trustee_crypto $ \(_crypto::Proxy c) -> runMaybeT $ do
-		(secKey::VP.E c) <- loadJSON glob trusteeDecrypt_privkey
+		(secKey::VP.E VP.FFC c) <- loadJSON glob trusteeDecrypt_privkey
 		let pubKey = VP.publicKey secKey
 		let trusteeKeysPath = trusteeDecrypt_url FP.</> "public_keys.jsons"
 		outputInfo glob "check that the public key is amongst the public keys of the election"
@@ -152,7 +157,8 @@
 				 (flip VP.insertEncryptedTally)
 				 VP.emptyEncryptedTally id $
 					readJSON glob ballotsPath
-			decShare <- Pip.liftIO $
+			decShare :: VP.DecryptionShare VP.FFC v c
+			 <- Pip.liftIO $
 				Rand.getStdRandom $ runState $
 					VP.proveDecryptionShare encTally secKey
-			return (coerce decShare :: VP.DecryptionShare ())
+			return (coerce decShare :: VP.DecryptionShare VP.FFC () ())
diff --git a/src/Hjugement/CLI/Utils.hs b/src/Hjugement/CLI/Utils.hs
--- a/src/Hjugement/CLI/Utils.hs
+++ b/src/Hjugement/CLI/Utils.hs
@@ -62,10 +62,26 @@
 	"Take cryptographic parameters from file "<>fileRef "FILE"<>"."
 	`help`
 	requiredTag "crypto" (var "FILE")
+api_param_version =
+	"Set the protocol version to use.\n"<>
+	"Defaults to the \"stable\" version.\n"<>
+	Doc.ul
+	 [ "stable       == "<>Doc.from (show VP.stableVersion)
+	 , "experimental == "<>Doc.from (show VP.experimentalVersion)
+	 ]
+	`help`
+	defaultTag "version" VP.stableVersion (
+		constant "stable" VP.stableVersion `alt`
+		constant "experimental" VP.experimentalVersion `alt`
+		var "VERSION"
+	 )
+instance CLI.IOType VP.Version
+instance CLI.FromSegment VP.Version where
+	fromSegment = return . maybe (Left "invalid version string") Right . VP.readVersion
 instance CLI.IOType VP.FFC
 instance CLI.FromSegment VP.FFC where
 	fromSegment = JSON.eitherDecodeFileStrict'
-instance VP.Reifies c VP.FFC => CLI.FromSegment (VP.E c) where
+instance VP.Reifies c VP.FFC => CLI.FromSegment (VP.E VP.FFC c) where
 	fromSegment = JSON.eitherDecodeFileStrict'
 api_param_uuid =
 	"UUID of the election."
@@ -77,8 +93,8 @@
 instance CLI.IOType VP.Credential
 instance CLI.FromSegment VP.Credential where
 	fromSegment = return . left show . VP.readCredential . Text.pack
-instance IOType (VP.DecryptionShare ())
-instance Outputable (VP.DecryptionShare ()) where
+instance IOType (VP.DecryptionShare VP.FFC () ())
+instance Outputable (VP.DecryptionShare VP.FFC () ()) where
 	output decShare = output $ JSON.encode decShare<>"\n"
 
 api_help full =
@@ -280,19 +296,28 @@
 		Doc.from err<>"\n"
 	 Right a -> return a
 
+-- | TODO: abstract over @crypto@ in the continuation.
 loadElection ::
+ VP.ReifyCrypto crypto =>
+ JSON.FromJSON crypto =>
  Pip.MonadIO m =>
  Global_Params ->
- IO.FilePath -> MaybeT m (VP.Election ())
-loadElection glob filePath =
+ IO.FilePath ->
+ (forall v c.
+  VP.Reifies v VP.Version =>
+  VP.Reifies c crypto =>
+  VP.FieldElementConstraints crypto c =>
+  VP.Election crypto v c -> MaybeT m r) ->
+ MaybeT m r
+loadElection glob filePath k =
 	Pip.liftIO ( do
 		outputDebug glob $ "loading " <> Doc.from filePath
-		runExceptT $ VP.readElection filePath
+		runExceptT $ VP.readElection filePath k
 	 ) >>= \case
 	 Left err -> outputError glob $
 		Doc.from filePath<>": "<>
 		Doc.from err<>"\n"
-	 Right a -> return a
+	 Right r -> r
 
 {-
 readJSON' ::
diff --git a/src/Hjugement/CLI/Voter.hs b/src/Hjugement/CLI/Voter.hs
--- a/src/Hjugement/CLI/Voter.hs
+++ b/src/Hjugement/CLI/Voter.hs
@@ -90,8 +90,8 @@
 run_voter_vote
  glob@Global_Params{..}
  VoterVote_Params{..} = runMaybeT $ do
-	rawElec <- loadElection glob $ voterVote_url FP.</> "election.json"
-	VP.reifyElection rawElec $ \(elec@VP.Election{..} :: VP.Election c) -> do
+	loadElection glob (voterVote_url FP.</> "election.json") $
+	 \(elec@VP.Election{..} :: VP.Election VP.FFC v c) -> do
 		outputInfo glob $ "Voted"<>Doc.from (show voterVote_grades)
 		votes <- VP.isoZipWithM
 		 (outputError glob $ "Mismatching number of cast grades ("<>
@@ -110,7 +110,7 @@
 		 election_questions
 		 voterVote_grades
 		outputInfo glob $ Doc.from (show votes)
-		let (secKey :: VP.SecretKey c) =
+		let (secKey :: VP.SecretKey VP.FFC c) =
 			VP.credentialSecretKey election_uuid voterVote_privcred
 		ballot <- join $ Pip.liftIO $
 			Rand.getStdRandom $ \gen ->
@@ -137,10 +137,10 @@
 run_voter_verify
  glob@Global_Params{..}
  VoterVerify_Params{..} = runMaybeT $ do
-	rawElec <- loadElection glob $ voterVerify_url FP.</> "election.json"
-	VP.reifyElection rawElec $ \(elec@VP.Election{..} :: VP.Election c) -> do
+	loadElection glob (voterVerify_url FP.</> "election.json") $
+	 \(elec@VP.Election{..} :: VP.Election VP.FFC v c) -> do
 		outputInfo glob $ "verifying ballots"
-		(fails :: Natural, (encTally :: VP.EncryptedTally c, _numBallots)) <- runPipeWithError glob $
+		(fails :: Natural, (encTally :: VP.EncryptedTally VP.FFC v c, _numBallots)) <- runPipeWithError glob $
 			Pip.foldM'
 			 (\(fails, acc@(_, numBallots)) ballot@VP.Ballot{..} -> do
 				let ballotNum = numBallots + fails
@@ -175,7 +175,7 @@
 		 then do
 			outputWarning glob "no tally to check"
 		 else do
-			tally :: VP.Tally c <- loadJSON glob resultPath
+			tally :: VP.Tally VP.FFC v c <- loadJSON glob resultPath
 			outputInfo glob $ "decrypting tally using trustees' decryption shares"
 			trustees <- runPipeWithError glob $ Pip.toListM' $
 				readJSON glob $ voterVerify_url FP.</> "public_keys.jsons"