Modulecrypton-1.0.4Haskell2010

Crypto.Cipher.ChaChaPoly1305

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

4 types
12 values

Packagecrypton-1.0.4
Exports16
LanguageHaskell2010
LicenceBSD-3-Clause
SourceChaChaPoly1305.hs

AEAD

2 declarations

typetype ChaCha20Poly1305 = State

A ChaChaPoly1305 State.

valueaeadChacha20poly1305Init

:: (ByteArrayAccess k, ByteArrayAccess n)
=> k
-> n
-> CryptoFailable (AEAD ChaCha20Poly1305)

Setting up AEAD for ChaCha20Poly1305.

Low level

14 declarations

datadata State

A ChaChaPoly1305 State.

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

datadata Nonce

Valid Nonce for ChaChaPoly1305.

It can be created with nonce8 or nonce12

Instances1ByteArrayAccess

ByteArrayAccess NonceDefined in crypton-1.0.4 · Crypto.Cipher.ChaChaPoly1305

newtypenewtype XNonce

Extended nonce for XChaChaPoly1305.

Instances1ByteArrayAccess

ByteArrayAccess XNonceDefined in crypton-1.0.4 · Crypto.Cipher.ChaChaPoly1305

valuenonce12 :: ByteArrayAccess iv => iv -> CryptoFailable Nonce

Nonce smart constructor 12 bytes IV, nonce constructor

valuenonce8

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

8 bytes IV, nonce constructor

valuenonce24 :: ByteArrayAccess ba => ba -> CryptoFailable XNonce

24 bytes IV, extended nonce constructor

valueincrementNonce :: Nonce -> Nonce

Increment a nonce

valueinitialize :: 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

valueinitializeX :: ByteArrayAccess key => key -> XNonce -> CryptoFailable State

Initialize a new XChaChaPoly1305 State

The key length needs to be 256 bits, and the nonce procured using nonce24.

valueappendAAD :: 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

valuefinalizeAAD :: State -> State

Finalize the Authenticated Data and return the finalized State

valueencrypt :: ByteArray ba => ba -> State -> (ba, State)

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

valuedecrypt :: ByteArray ba => ba -> State -> (ba, State)

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

valuefinalize :: State -> Auth

Generate an authentication tag from the State.