Safe Haskell	Safe-Inferred
Language	GHC2021

Hydra.Tx.Secret

Description

A type-level barrier around values that must never be shown, logged, or serialised.

Wrapping a value in Secret makes the following a compile-time error (via TypeError) with a custom message:

ToJSON / FromJSON
ToCBOR / FromCBOR
Serialise

Show is provided but renders as a redacted placeholder ("<Secret field of type <typename>>"), so enclosing records can still deriving stock (Show) for free.

The only way to read the wrapped value is withSecret, a continuation- style accessor: there is intentionally no revealSecret :: Secret a -> a. That forces every consumption site to be a small lexical scope and keeps raw values from outliving the use site.

Synopsis

data Secret a
mkSecret :: a -> Secret a
withSecret :: Secret a -> (a -> r) -> r
type Forbid op = TypeError ((((((((('Text "Refusing to " ':<>: 'Text op) ':<>: 'Text " a value marked as secret.") ':$$: 'Text "Secret values (e.g. signing keys) must not be") ':$$: 'Text "shown, logged, or serialised. Use `withSecret` from") ':$$: 'Text "Hydra.Tx.Secret to consume the inner value at its") ':$$: 'Text "point of use (e.g. signing). If you got here from a") ':$$: 'Text "derived `Show` / `ToJSON` on an enclosing record,") ':$$: 'Text "either drop that deriving clause or write a") ':$$: 'Text "hand-rolled instance that omits the secret field.")

Documentation

data Secret a Source #

A value the type system refuses to show or serialise.

Instances

Instances details

(Forbid "decode from JSON" :: Constraint) => FromJSON (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods parseJSON :: Value -> Parser (Secret a) parseJSONList :: Value -> Parser [Secret a] omittedField :: Maybe (Secret a)
(Forbid "encode to JSON" :: Constraint) => ToJSON (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods toJSON :: Secret a -> Value toEncoding :: Secret a -> Encoding toJSONList :: [Secret a] -> Value toEncodingList :: [Secret a] -> Encoding omitField :: Secret a -> Bool
Typeable a => Show (Secret a) Source #	Renders as `"<Secret field of type <typename>>"`. The `Typeable` constraint lets the instance name the wrapped type without ever touching the value. Enclosing records can keep using 'deriving stock (Show)' and get a redacted rendering for free.
Instance details Defined in Hydra.Tx.Secret Methods showsPrec :: Int -> Secret a -> ShowS Source # show :: Secret a -> String Source # showList :: [Secret a] -> ShowS Source #
(Typeable a, Forbid "CBOR-decode" :: Constraint) => FromCBOR (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods fromCBOR :: Decoder s (Secret a) label :: Proxy (Secret a) -> Text
(Typeable a, Forbid "CBOR-encode" :: Constraint) => ToCBOR (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods toCBOR :: Secret a -> Encoding encodedSizeExpr :: (forall t. ToCBOR t => Proxy t -> Size) -> Proxy (Secret a) -> Size encodedListSizeExpr :: (forall t. ToCBOR t => Proxy t -> Size) -> Proxy [Secret a] -> Size
Eq a => Eq (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods (==) :: Secret a -> Secret a -> Bool Source # (/=) :: Secret a -> Secret a -> Bool Source #
Ord a => Ord (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods compare :: Secret a -> Secret a -> Ordering Source # (<) :: Secret a -> Secret a -> Bool Source # (<=) :: Secret a -> Secret a -> Bool Source # (>) :: Secret a -> Secret a -> Bool Source # (>=) :: Secret a -> Secret a -> Bool Source # max :: Secret a -> Secret a -> Secret a Source # min :: Secret a -> Secret a -> Secret a Source #
CanSignTx (Secret (SigningKey PaymentKey)) Source #
Instance details Defined in Hydra.Tx.Crypto Methods signTx :: Secret (SigningKey PaymentKey) -> Tx -> Tx Source #
(Forbid "Serialise-encode" :: Constraint) => Serialise (Secret a) Source #
Instance details Defined in Hydra.Tx.Secret Methods encode :: Secret a -> Encoding decode :: Decoder s (Secret a) encodeList :: [Secret a] -> Encoding decodeList :: Decoder s [Secret a]
(Key k, HasTypeProxy k) => HasVerificationKey (Secret (SigningKey k)) k Source #
Instance details Defined in Hydra.Tx.Crypto Methods getVerificationKey :: Secret (SigningKey k) -> VerificationKey k Source #

mkSecret :: a -> Secret a Source #

withSecret :: Secret a -> (a -> r) -> r Source #

The only escape hatch. Continuation-style so the raw value is never bound at the call site outside the supplied function.

type Forbid op = TypeError ((((((((('Text "Refusing to " ':<>: 'Text op) ':<>: 'Text " a value marked as secret.") ':$$: 'Text "Secret values (e.g. signing keys) must not be") ':$$: 'Text "shown, logged, or serialised. Use `withSecret` from") ':$$: 'Text "Hydra.Tx.Secret to consume the inner value at its") ':$$: 'Text "point of use (e.g. signing). If you got here from a") ':$$: 'Text "derived `Show` / `ToJSON` on an enclosing record,") ':$$: 'Text "either drop that deriving clause or write a") ':$$: 'Text "hand-rolled instance that omits the secret field.") Source #