Crypto.Cipher.ChaChaPoly1305

cryptonite-0.20: Cryptography Primitives sink

License | BSD-style
Maintainer | Vincent Hanquez <vincent@snarc.org>
Stability | stable
Portability | good
Safe Haskell | None
Language | Haskell2010

Crypto.Cipher.ChaChaPoly1305

Description

A simple AEAD scheme using ChaCha20 and Poly1305. See RFC 7539.

The State is not modified in place, so each function changing the State, returns a new State.

Authenticated Data need to be added before any call to `encrypt` or `decrypt`, and once all the data has been added, then `finalizeAAD` need to be called.

Once `finalizeAAD` has been called, no further `appendAAD` call should be make.

    import Data.ByteString.Char8 as B
    import Data.ByteArray
    import Crypto.Error
    import Crypto.Cipher.ChaChaPoly1305 as C

    encrypt
        :: ByteString -- nonce (12 random bytes)
        -> ByteString -- symmetric key
        -> ByteString -- optional associated data (won't be encrypted)
        -> ByteString -- input plaintext to be encrypted
        -> CryptoFailable ByteString -- ciphertext with a 128-bit tag attached
    encrypt nonce key header plaintext = do
        st1 <- C.nonce12 nonce >>= C.initialize key
        let
            st2 = C.finalizeAAD $ C.appendAAD header st1
            (out, st3) = C.encrypt plaintext st2
            auth = C.finalize st3
        return $ out `B.append` Data.ByteArray.convert auth

Synopsis

- data State
- data Nonce
- nonce12 :: ByteArrayAccess iv => iv -> CryptoFailable Nonce
- nonce8 :: ByteArrayAccess ba => ba -> ba -> CryptoFailable Nonce
- incrementNonce :: Nonce -> Nonce
- initialize :: ByteArrayAccess key => key -> Nonce -> CryptoFailable State
- appendAAD :: ByteArrayAccess ba => ba -> State -> State
- finalizeAAD :: State -> State
- encrypt :: ByteArray ba => ba -> State -> (ba, State)
- decrypt :: ByteArray ba => ba -> State -> (ba, State)
- finalize :: State -> Auth

# Documentation

data State #

A ChaChaPoly1305 State.

The state is immutable, and only new state can be created

data Nonce #

Valid Nonce for ChaChaPoly1305.

It can be created with `nonce8` or `nonce12`

Instances

ByteArrayAccess Nonce # |
Methods length :: Nonce -> Int # withByteArray :: Nonce -> (Ptr p -> IO a) -> IO a #

nonce12 :: ByteArrayAccess iv => iv -> CryptoFailable Nonce #

Nonce smart constructor 12 bytes IV, nonce constructor

nonce8 #

Arguments

:: ByteArrayAccess ba |
=> ba | 4 bytes constant
-> ba | 8 bytes IV
-> CryptoFailable Nonce |

8 bytes IV, nonce constructor

incrementNonce :: Nonce -> Nonce #

Increment a nonce

initialize :: ByteArrayAccess key => key -> Nonce -> CryptoFailable State #

Initialize a new ChaChaPoly1305 State

The key length need to be 256 bits, and the nonce procured using either `nonce8` or `nonce12`

appendAAD :: ByteArrayAccess ba => ba -> State -> State #

Append Authenticated Data to the State and return the new modified State.

Once no further call to this function need to be make, the user should call `finalizeAAD`

finalizeAAD :: State -> State #

Finalize the Authenticated Data and return the finalized State

encrypt :: ByteArray ba => ba -> State -> (ba, State) #

Encrypt a piece of data and returns the encrypted Data and the updated State.

decrypt :: ByteArray ba => ba -> State -> (ba, State) #

Decrypt a piece of data and returns the decrypted Data and the updated State.

finalize :: State -> Auth #

Generate an authentication tag from the State.