SecLib.Untrustworthy

The security library. This is the only module of the library to be imported by untrustworthy code.

Documentation

data Sec s a

This type represents pure values of type a at confidentiality level s.

Instances

Monad (Sec s)

Functor (Sec s)

up :: Less s s' => Sec s a -> Sec s' a

Raise the confidentiality level of values.

public :: Attacker s => Sec s a -> a

Reveal values that the attacker can observe.

data SecIO s a

This type represents secure side-effect computations. These computations perform side-effects at security level, at least, s and return a value of type a with confidentiality level, at least, s.

Instances

Monad (SecIO s)

Functor (SecIO s)

value :: Sec s a -> SecIO s a

Lift a pure confidential value into a secure side-effect computation.

plug :: Less sl sh => SecIO sh a -> SecIO sl (Sec sh a)

Safely downgrade the security level indicating the side-effects performed by the computation.

run :: SecIO s a -> IO (Sec s a)

Execute secure computations.

type File s = Loc FilePath s String ()

Locations that represent files

readFileSecIO :: File s -> SecIO s' (Sec s String)

Secure read operation for files.

writeFileSecIO :: File s -> String -> SecIO s ()

Secure write operation for files.

type Ref s a = Loc (IORef a) s a ()

Locations that represent references.

readRefSecIO :: Ref s a -> SecIO s' (Sec s a)

Secure read operation for references.

writeRefSecIO :: Ref s a -> a -> SecIO s ()

Secure write operation for references.

newIORefSecIO :: s -> a -> SecIO s' (Ref s a)

Secure creation of a reference. We assume that the attacker has no manner to observe the side-effect of creating a reference from inside of the program, for example, by inspecting the amount of free memory. At the moment, there are no such functions inside of the monad SecIO. Nevertheless, if there is a consideration of include, for instance, a function that returns the amount of free memory in the program, then the function type of newIORefSecIO needs to be changed.

type Screen s = Attacker s => Loc () s String ()

Location that represents the screen-keyword. Here, we can choose between a) The attacker is on the screen-keyword, which implies that when taking input from the screen has an effect -- the attacker can see when the input is required. Therefore, we need to implement taking input from the keyword using effectful_read. b) The attacker is not on the screen-keyword. In this case, we implement reading using effectless_read. We choose option a) as a model.

getLineSecIO :: Attacker s => Screen s -> SecIO s String

Secure input from the keyword.

putStrSecIO :: Attacker s => Screen s -> String -> SecIO s ()

Secure output to the screen.

putStrLnSecIO :: Attacker s => Screen s -> String -> SecIO s ()

Secure output to the screen.

s_read :: Less s' s => File s' -> SecIO s String

It is a derived operation for reading from files (legacy code).

s_write :: Less s s' => File s' -> String -> SecIO s (Sec s' ())

It is a derived operation for writing into files (legacy code).

type SecSocket s = Loc (Socket, Int) s String Int

Locations that represent network communications via sockets.

data SecSockAddr s

It defines a socket address at confidentiality level s.

inet_addrSecIO :: String -> SecIO s HostAddress

Wrapper for inet_addr.

portInet :: PortNumber -> SecSockAddr s -> SecSockAddr s

Assing a port to the AF_INET sockets. Port numbers are public.

socketSecIO :: Family -> SocketType -> ProtocolNumber -> SecIO s' (SecSocket s)

Create a socket at confidentiality level s. The creation has no visible side-effects, e.g. sockets cannot be compared. This function is essentially a wrapper for socket.

bindSocketSecIO :: SecSocket s -> SecSockAddr s -> SecIO s ()

sIsBoundSecIO :: SecSocket s -> SecIO s' (Sec s Bool)

Return if a socket is bound to some address.

acceptSecIO :: SecSocket s -> SecIO s (SecSocket s, SecSockAddr s)

Wrapper for accept.

recvSecIO :: SecSocket s -> Int -> SecIO s String

Secure read operation for sockets.

sendSecIO :: SecSocket s -> String -> SecIO s Int

Secure write operation for sockets.

connectSecIO :: SecSocket s -> SecSockAddr s -> SecIO s ()

Connects to a socket. It is a wrapper for connect.

sIsConnectedSecIO :: SecSocket s -> SecIO s' (Sec s Bool)

Determines a given socket is connected. It is a wrapper for sIsConnected.

data Authority s

Used by dlm.

certify :: sh -> Authority sh -> SecIO s a -> SecIO s a

Certify that a piece of code have certain authority.

class Less s s'

Instances

Less a a

Information can flow among entities of the same level.

Less L H

Public information can become secret.

class Attacker s

Instances

Attacker L

The attacker can observe public data.