content: {-# LANGUAGE TypeFamilies #-}
  
  module QuantumResistantCryptography where
  
  import qualified Data.ByteString as BS
  import qualified Crypto.Hash as H
  import qualified Crypto.PubKey.Curve25519 as C
  
  -- Define the quantum-resistant cryptographic scheme
  data QuantumResistantCrypto = QuantumResistantCrypto
    { privateKey :: C.PrivateKey
    , publicKey :: C.PublicKey
    }
  
  -- Generate a new key pair
  generateKeyPair :: IO QuantumResistantCrypto
  generateKeyPair = do
    privateKey <- C.generatePrivateKey
    publicKey <- C.derivePublicKey privateKey
    return $ QuantumResistantCrypto privateKey publicKey
  
  -- Encrypt a message using the public key
  encrypt :: QuantumResistantCrypto -> BS.ByteString -> BS.ByteString
  encrypt crypto message = do
    let publicKey = publicKey crypto
    C.encrypt publicKey message
  
  -- Decrypt a message using the private key
  decrypt :: QuantumResistantCrypto -> BS.ByteString -> BS.ByteString
  decrypt crypto ciphertext = do
    let privateKey = privateKey crypto
    C.decrypt privateKey ciphertext
  
  -- Example usage
  main :: IO ()
  main = do
    crypto <- generateKeyPair
    let message = "Hello, World!"
    let ciphertext = encrypt crypto (BS.pack message)
    let plaintext = decrypt crypto ciphertext
    print plaintext
  