path: root/keys.hs

{-# LANGUAGE ViewPatterns  #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE CPP #-}
module Main where

import Debug.Trace
import Data.Binary
import Data.OpenPGP
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Lazy.Char8 as Char8
import qualified Data.ByteString      as S
import Control.Monad
import qualified Text.Show.Pretty as PP
import Text.PrettyPrint as PP
import Data.List
import Data.OpenPGP.CryptoAPI
import Data.Ord
import Data.Maybe
import Data.Bits
import qualified Data.Text as T
import Data.Text.Encoding
import qualified Codec.Binary.Base32 as Base32
import qualified Crypto.Hash.SHA1 as SHA1
import Data.Char (toLower)
import qualified Crypto.PubKey.RSA as RSA
import Data.ASN1.Types
import Data.ASN1.Encoding
import Data.ASN1.BinaryEncoding
import Control.Applicative
import System.Environment
import System.Directory
import System.Exit
import ControlMaybe
import Data.Char
import Control.Arrow (second)
import Data.Traversable
import System.Console.CmdArgs

data RSAPublicKey = RSAKey MPI MPI

instance ASN1Object RSAPublicKey where
    toASN1 (RSAKey (MPI n) (MPI e))
                  = \xs -> Start Sequence
                         : IntVal n
                         : IntVal e
                         : End Sequence
                         : xs
    fromASN1 (Start Sequence:IntVal modulus:IntVal pubexp:End Sequence:xs) =
        Right (RSAKey (MPI modulus) (MPI pubexp) , xs)
    fromASN1 _ =
        Left "fromASN1: RSAPublicKey: unexpected format"

rsaKeyFromPacket p@(PublicKeyPacket {}) = do
    n <- lookup 'n' $ key p
    e <- lookup 'e' $ key p
    return $ RSAKey n e
rsaKeyFromPacket p@(SecretKeyPacket {}) = do
    n <- lookup 'n' $ key p
    e <- lookup 'e' $ key p
    return $ RSAKey n e
rsaKeyFromPacket _ = Nothing
derRSA rsa = do
    k <- rsaKeyFromPacket rsa
    return $ encodeASN1 DER (toASN1 k [])

getPackets :: IO [Packet]
getPackets = do
    input <- L.getContents
    case decodeOrFail input of
        Right (_,_,Message pkts) -> return pkts
        Left  (_,_,_)            -> return []


isKey (PublicKeyPacket {}) = True
isKey (SecretKeyPacket {}) = True
isKey _                    = False

isUserID (UserIDPacket {}) = True
isUserID _                 = False

isEmbeddedSignature (EmbeddedSignaturePacket {}) = True
isEmbeddedSignature _                            = False

isCertificationSig (CertificationSignature {}) = True
isCertificationSig _                           = True

issuer (IssuerPacket issuer) = Just issuer
issuer _                     = Nothing
backsig (EmbeddedSignaturePacket s) = Just s
backsig _                           = Nothing

isSubkeySignature (SubkeySignature {}) = True
isSubkeySignature _                    = False

usage (NotationDataPacket
        { human_readable = True
        , notation_name  = "usage@"
        , notation_value = u
        }) = Just u
usage _    = Nothing

verifyBindings keys nonkeys = (top ++ filter isSubkeySignature embedded,othersigs)
 where
    verified = do
        sig <- signatures (Message nonkeys)
        let v = verify (Message keys) sig
        guard (not . null $ signatures_over v)
        return v
    (top,othersigs) = partition isSubkeySignature verified
    embedded = do
        sub <- top
        let sigover = signatures_over sub
            unhashed = sigover >>= unhashed_subpackets
            subsigs = mapMaybe backsig unhashed
        sig <- signatures (Message ([topkey sub,subkey sub]++subsigs))
        let v = verify (Message [subkey sub]) sig
        guard (not . null $ signatures_over v)
        return v

grip k = drop 32 $ fingerprint k

smallpr k = drop 24 $ fingerprint k

disjoint_fp ks = {- concatMap group2 $ -} transpose grouped
 where
    grouped    = groupBy samepr . sortBy (comparing smallpr) $ ks
    samepr a b = smallpr a == smallpr b

    {-
    -- useful for testing
    group2 :: [a] -> [[a]]
    group2 (x:y:ys) = [x,y]:group2 ys
    group2 [x]      = [[x]]
    group2 []       = []
    -}

getBindings ::
  [Packet]
  -> 
    ( [([Packet],[SignatureOver])] -- ^ other signatures with key sets
                                   --   that were used for the verifications
    , [(Word8,
       (Packet, Packet),
       [String],
       [SignatureSubpacket],
       [Packet])] -- ^ binding signatures
    )
getBindings pkts = (sigs,bindings)
 where
    (sigs,concat->bindings) = unzip $ do
        let (keys,nonkeys) = partition isKey pkts
        keys <- disjoint_fp keys
        let (bs,sigs) = verifyBindings keys pkts
        return . ((keys,sigs),) $ do
            b <- bs
            i <- map signature_issuer (signatures_over b)
            i <- maybeToList i
            who <- maybeToList $ find_key fingerprint (Message keys) i
            let (code,claimants) = 
                    case () of
                        _ | who == topkey b -> (1,[])
                        _ | who == subkey b -> (2,[])
                        _                   -> (0,[who])
            let hashed = signatures_over b >>= hashed_subpackets
                kind = guard (code==1) >> hashed >>= maybeToList . usage
            return (code,(topkey b,subkey b), kind, hashed,claimants)

accBindings ::
  Bits t =>
  [(t, (Packet, Packet), [a], [a1], [a2])]
  -> [(t, (Packet, Packet), [a], [a1], [a2])]
accBindings bs = as
  where
    gs = groupBy samePair . sortBy (comparing bindingPair) $ bs
    as = map (foldl1 combine) gs
    bindingPair (_,p,_,_,_) = pub2 p
      where
        pub2 (a,b) = (pub a, pub b)
        pub a = fingerprint_material a
    samePair a b = bindingPair a == bindingPair b
    combine (ac,p,akind,ahashed,aclaimaints)
            (bc,_,bkind,bhashed,bclaimaints)
        = (ac .|. bc,p,akind++bkind,ahashed++bhashed,aclaimaints++bclaimaints)


data UserIDRecord = UserIDRecord {
    uid_full :: String,
    uid_realname :: T.Text,
    uid_user :: T.Text,
    uid_subdomain :: T.Text,
    uid_topdomain :: T.Text
}

isBracket '<' = True
isBracket '>' = True
isBracket _   = False

parseUID str = UserIDRecord {
                    uid_full = str,
                    uid_realname = realname,
                    uid_user = user,
                    uid_subdomain = subdomain,
                    uid_topdomain = topdomain
                }
 where
    text = T.pack str
    (T.strip-> realname, T.dropAround isBracket-> email) 
                              = T.break (=='<') text
    (user, T.tail-> hostname) = T.break (=='@') email
    ( T.reverse            -> topdomain,
      T.reverse . T.drop 1 -> subdomain)
                              = T.break (=='.') . T.reverse $ hostname


derToBase32 = map toLower . Base32.encode . S.unpack . SHA1.hashlazy

fpmatch grip key = 
    (==) Nothing
         (fmap (backend (fingerprint key)) grip >>= guard . not)
 where
    backend xs ys = and $ zipWith (==) (reverse xs) (reverse ys)

listKeys pkts = listKeysFiltered Nothing pkts

listKeysFiltered grip pkts = do
    let (certs,bs) = getBindings pkts
        as = accBindings bs
        defaultkind (k:_) hs = k
        defaultkind []    hs = maybe "subkey"
                                     id
                                     ( listToMaybe 
                                     . mapMaybe (fmap usageString . keyflags)
                                     $ hs)
        kinds = map (\(_,_,k,h,_)->defaultkind k h) as
        kindwidth = maximum $ map length kinds
        kindcol = min 20 kindwidth
        code (c,(m,s),_,_,_) = (fingerprint_material m,-c)
        ownerkey (_,(a,_),_,_,_) = a
        sameMaster (ownerkey->a) (ownerkey->b) = fingerprint_material a==fingerprint_material b
        matchgrip ((code,(top,sub), kind, hashed,claimants):_) | fpmatch grip top = True
        matchgrip _ = False
        gs = filter matchgrip $ groupBy sameMaster (sortBy (comparing code) as)
    subs <- gs
    let (code,(top,sub), kind, hashed,claimants):_ = subs
        subkeys = do
            (code,(top,sub), kind, hashed,claimants) <- subs
            let ar = case code of
                        0 -> " ??? "
                        1 -> " --> "
                        2 -> " <-- "
                        3 -> " <-> "
                formkind = take kindcol $ defaultkind kind hashed ++ repeat ' '
                -- torhash = maybe "" id $ derToBase32 <$> derRSA sub
            concat  [ " "
                    -- , grip top
                    , ar
                    , formkind 
                    , " "
                    , fingerprint sub 
                    -- , " " ++ torhash
                    , "\n" ]
                -- ++ ppShow hashed
        torkeys = do
            (code,(top,sub), kind, hashed,claimants) <- subs
            guard ("tor" `elem` kind)
            guard (code .&. 0x2 /= 0)
            maybeToList $ derToBase32 <$> derRSA sub
        uid = {- maybe "" id . listToMaybe $ -} do
            (keys,sigs) <- certs
            sig <- sigs
            guard (isCertificationSig sig)
            guard (topkey sig == top)
            sig_over <- signatures_over sig
            guard (join (fmap (find_key smallpr (Message keys)) $ signature_issuer sig_over) == Just top)
            let UserIDPacket uid = user_id sig
                parsed = parseUID uid
                ar = maybe " --> " (const " <-> ") $ do
                        guard (uid_topdomain parsed == "onion" )
                        guard ( uid_realname parsed `elem` ["","Anonymous"])
                        guard (     uid_user parsed == "root" )
                        let subdom0 = L.fromChunks [encodeUtf8 (uid_subdomain parsed)]
                            len = L.length subdom0
                            subdom = Char8.unpack subdom0
                            match = ( (==subdom) . take (fromIntegral len))
                        guard (len >= 16)
                        listToMaybe $ filter match torkeys
            " " ++ ar ++ "@" ++ " " ++ uid_full parsed ++ "\n"
        (_,sigs) = unzip certs
    "master-key " ++ fingerprint top ++ "\n" ++ uid ++"  ...\n" ++ subkeys ++ "\n"
    

data PGPKeyFlags =
    Special
    | Vouch
    | Sign
    | VouchSign
    | Communication
    | VouchCommunication
    | SignCommunication
    | VouchSignCommunication
    | Storage
    | VouchStorage
    | SignStorage
    | VouchSignStorage
    | Encrypt
    | VouchEncrypt
    | SignEncrypt
    | VouchSignEncrypt
 deriving (Eq,Show,Read,Enum)

usageString flgs = 
 case flgs of
    Special -> "special"
    Vouch -> "vouch"
    Sign -> "sign"
    VouchSign -> "vouch-sign"
    Communication -> "communication"
    VouchCommunication -> "vouch-communication"
    SignCommunication -> "sign-communication"
    VouchSignCommunication -> "vouch-sign-communication"
    Storage -> "storage"
    VouchStorage -> "vouch-storage"
    SignStorage -> "sign-storage"
    VouchSignStorage -> "vouch-sign-storage"
    Encrypt -> "encrypt"
    VouchEncrypt -> "vouch-encrypt"
    SignEncrypt -> "sign-encrypt"
    VouchSignEncrypt -> "vouch-sign-encrypt"


keyflags flgs@(KeyFlagsPacket {}) =
    Just . toEnum $
        (   bit 0x1 certify_keys 
        .|. bit 0x2 sign_data
        .|. bit 0x4 encrypt_communication
        .|. bit 0x8 encrypt_storage )     :: Maybe PGPKeyFlags
    -- other flags:
    --  split_key
    --  authentication (ssh-client)
    --  group_key
 where
    bit v f = if f flgs then v else 0
keyflags _ = Nothing


modifyUID (UserIDPacket str) = UserIDPacket str'
 where
    (fstname,rst) = break (==' ') str
    str' = mod fstname ++ rst
    mod "Bob" = "Bob Fucking"
    mod x     = x
modifyUID other              = other

todo = error "unimplemented"

-- TODO: switch to System.Environment.lookupEnv
--       when linking against newer base libraries.
lookupEnv var = 
    handleIO_ (return Nothing) $ fmap Just (getEnv var)

unmaybe def = fmap (maybe def id)

expandPath path (c:cs) | c/='/'    = path ++ "/" ++ (c:cs)
                       | otherwise = c:cs
expandPath path []                 = []


readPacketsFromFile :: FilePath -> IO Message
readPacketsFromFile fname = do
    input <- L.readFile fname
    return $
      case decodeOrFail input of
        Right (_,_,msg ) -> msg
        Left  (_,_,_)    -> Message []


parseOptionFile fname = do
    xs <- fmap lines (readFile fname)
    let ys = filter notComment xs
        notComment ('#':_) = False
        notComment cs      = not (all isSpace cs)
    return ys

{-
options_from_file :: 
        (forall a. [String] -> Term a -> IO (Either EvalExit a)) 
        -> Term b 
        -> (String,String,Term (Maybe String)) 
        -> ([String],Term (Maybe String)) 
        -> IO [String]
options_from_file unwrapCmd term (homevar,appdir,home) (optfile_alts,options_file) = doit
 where
    homedir = envhomedir <$> home
    envhomedir opt = do
        gnupghome <- lookupEnv homevar >>=
                  \d -> return $ d >>= guard . (/="") >> d
        home <- flip fmap getHomeDirectory $
                  \d -> fmap (const d) $ guard (d/="")
        let homegnupg = (++('/':appdir)) <$> home
        let val = (opt `mplus` gnupghome `mplus` homegnupg)
        return $ val

    doit = do
        args <- getArgs
        {-
        let wants_help = 
                not . null $ filter cryForHelp args
                        where cryForHelp "--help"    = True
                              cryForHelp "--version" = True
                              cryForHelp x = 
                                and (zipWith (==) x "--help=")
        -}
        (o,h) <- do
            val <- unwrapCmd args (liftA2 (,) options_file homedir)
            case val of
                Left e -> return (Nothing,Nothing)
                Right (o,h)    -> (o,) <$> h
        ofile <- fmap listToMaybe . flip (maybe (return [])) h $ \h -> 
                let optfiles = map (second ((h++"/")++)) 
                                   (maybe optfile_alts' (:[]) o')
                    optfile_alts' = zip (False:repeat True) optfile_alts
                    o' = fmap (False,) o
                in filterM (doesFileExist . snd) optfiles
        args <- flip (maybe $ return args) ofile $ \(forgive,fname) -> do
            let h' = fromJust h
            newargs <- (:) <$> pure ("homedir "++h') <*> parseOptionFile fname
            let toArgs = toHead ("--"++) . words
                toHead f (x:xs) = f x : xs
                toHead f []     = []
                voidTerm = fmap (const ())
                appendArgs as [] = return as
                appendArgs as (configline:cs) = do
                    let xs = toArgs configline
                    w <-unwrap (xs++as) (voidTerm term,defTI)
                    case w of
                        Left  _ -> appendArgs as cs
                        Right _ -> appendArgs (xs++as) cs
            -- TODO: check errors if forgive = False
            appendArgs args newargs
        return args

runWithOptionsFile :: (Term (IO b), TermInfo) -> IO b
runWithOptionsFile (term,ti) = do
    as <- options_from_file unwrapCmd
                            term
                            ("GNUPGHOME",".gnupg",opt_homedir)
                            (["keys.conf","gpg.conf-2","gpg.conf"]
                            ,opt_options)
    q <- eval as (term , ti)
    q
 where
    unwrapCmd args term = unwrap args (term,defTI)

runChoiceWithOptionsFile ::
  (Term (IO b), TermInfo) -> [(Term (IO b), TermInfo)] -> IO b
runChoiceWithOptionsFile (realterm,ti) choices = do
    as <- options_from_file unwrapCmd
                            realterm
                            ("GNUPGHOME",".gnupg",opt_homedir)
                            (["keys.conf","gpg.conf-2","gpg.conf"]
                            ,opt_options)
    -- putStrLn $ "as = " ++ show as
    q <- evalChoice as (realterm , ti) choices
    q
 where
    unwrapCmd args t = 
        unwrapChoice args (realterm <:> t,ti) (map (neuter t) choices)
    neuter term (t,ti) = (t <:> term, ti)

data Command = 
    List
    | Autosign
 deriving (Eq,Show,Read,Enum)

capitolizeFirstLetter (x:xs) = toUpper x : xs
capitolizeFirstLetter xs     = xs

instance ArgVal Command where 
    converter = 
      ( maybe (Left $ text "unknown command") Right 
        . fmap fst . listToMaybe . reads 
        . capitolizeFirstLetter . map toLower
      , text . map toLower . show 
      )
class AutoMaybe a
instance AutoMaybe Command
instance (ArgVal a, AutoMaybe a) => ArgVal (Maybe a) where
    converter =
      ( toRight Just . fst converter
      , maybe (text "(unspecified)") id . fmap (snd converter)
      )

toRight f (Right x) = Right (f x)
toRight f (Left y)  = Left  y

cmd :: Term Command
cmd = required . pos 0 Nothing $ posInfo 
  { posName = "command"
  , posDoc  = "What action to perform."
  }

a <:> b = flip const <$> a <*> b
infixr 2 <:>


selectAction cmd actions = actions !! fromEnum cmd

cmdInfo :: ArgVal cmd => 
    cmd -> String -> Term a -> (cmd, (Term a, TermInfo))
cmdInfo cmd doc action = 
    ( cmd
    , ( action
      , defTI { termName = print cmd
              , termDoc  = doc } ) )
  where
    print = show . snd converter

cmdlist :: (Command, (Term (IO ()), TermInfo))
cmdlist = cmdInfo List "list key pairs for which secrets are known" $
    (>>= putStrLn . listKeys . unMessage) <$> secret_packets
 where unMessage (Message pkts) = pkts

cmdautosign = cmdInfo Autosign "auto-sign tor-style uids" $
    pure (putStrLn "autosign")


multiCommand ::
  TermInfo
  -> [(Command, (Term a, TermInfo))]
  -> ( (Term a, TermInfo)
     , [(Term a, TermInfo)] )
multiCommand ti choices = 
    ( ( selectAction <$> cmd <*> sequenceA (map strip choices)
      , ti )
    , map snd choices )
 where
    selectAction cmd choices =
        fromJust $ lookup (cmd::Command) choices
    strip (cmd,(action,_)) = fmap (cmd,) action
-}

data Arguments = 
        List { homedir :: Maybe FilePath }
        | WorkingKey { homedir :: Maybe FilePath }
        | AutoSign { homedir :: Maybe FilePath, input :: FilePath, output :: FilePath}
  deriving (Show, Data, Typeable)

#define HOMEOPTION (def &= explicit &= name "homedir" &= typDir )

main = do
    args <- cmdArgs $ modes 
        [ List HOMEOPTION
            &= help "List key pairs in the secret keyring."
            &= auto
        , WorkingKey HOMEOPTION
            &= help "Shows the current working key set that will be used to make signatures."
        , AutoSign HOMEOPTION (def &= argPos 1 &= typFile ) (def &=argPos 2 &= typFile) 
            &= (help . concat)
                    [ "Copies the first file to the second while adding"
                    , " signatures for tor-style uids that match"
                    , " cross-certified keys." ]
        ]
        &= program "keys"
        &= summary "keys - a pgp key editing utility"
    doCmd args
 where
    envhomedir opt = do
        gnupghome <- lookupEnv homevar >>=
                  \d -> return $ d >>= guard . (/="") >> d
        home <- flip fmap getHomeDirectory $
                  \d -> fmap (const d) $ guard (d/="")
        let homegnupg = (++('/':appdir)) <$> home
        let val = (opt `mplus` gnupghome `mplus` homegnupg)
        return $ val

    homevar = "GNUPGHOME"
    appdir  = ".gnupg"
    optfile_alts = ["keys.conf","gpg.conf-2","gpg.conf"]

    getHomeDir cmd = do
        homedir <- envhomedir (homedir cmd)
        flip (maybe (error "Could not determine home directory."))
             homedir $ \homedir -> do
        -- putStrLn $ "homedir = " ++show homedir
        let secring = homedir ++ "/" ++ "secring.gpg"
        -- putStrLn $ "secring = " ++ show secring
        workingkey <- getWorkingKey homedir
        return (homedir,secring,workingkey)

    getWorkingKey homedir = do
        let o = Nothing
            h = Just homedir
            args = ["hi"]
        ofile <- fmap listToMaybe . flip (maybe (return [])) h $ \h -> 
                let optfiles = map (second ((h++"/")++)) 
                                   (maybe optfile_alts' (:[]) o')
                    optfile_alts' = zip (False:repeat True) optfile_alts
                    o' = fmap (False,) o
                in filterM (doesFileExist . snd) optfiles
        args <- flip (maybe $ return []) ofile $ 
            \(forgive,fname) -> parseOptionFile fname
        let config = map (topair . words) args
                        where topair (x:xs) = (x,xs)
        return $ lookup "default-key" config >>= listToMaybe


    doCmd cmd@(List {}) = do
        (homedir,secring,grip) <- getHomeDir cmd
        (Message sec) <- readPacketsFromFile secring
        putStrLn $ listKeys sec

    doCmd cmd@(WorkingKey {}) = do
        (homedir,secring,grip) <- getHomeDir cmd
        (Message sec) <- readPacketsFromFile secring
        putStrLn $ listKeysFiltered grip sec
        return ()

    doCmd cmd@(AutoSign {}) = do
        (homedir,secring,grip) <- getHomeDir cmd
        (Message sec) <- readPacketsFromFile secring
        (Message pub) <- readPacketsFromFile (input cmd)
        putStrLn $ "Inspecting packets..."
        putStrLn $ listKeys pub
        return ()