import Control.Monad
import Data.List
import Data.Maybe
import OpenSSL
import OpenSSL.EVP.Cipher
import OpenSSL.EVP.Open
import OpenSSL.EVP.PKey
import OpenSSL.EVP.Seal
import OpenSSL.PEM
import OpenSSL.RSA
import Text.Printf


main = withOpenSSL $
       do putStrLn "cipher: DES-CBC"
          des <- liftM fromJust $ getCipherByName "DES-CBC"

          putStrLn "generating RSA keypair..."
          rsa <- generateRSAKey 512 65537 Nothing

          let plainText = "Hello, world!"
          putStrLn ("plain text to encrypt: " ++ plainText)

          putStrLn ""

          putStrLn "encrypting..."
          (encrypted, [encKey], iv) <- seal des [fromPublicKey rsa] plainText
          
          putStrLn ("encrypted symmetric key: " ++ binToHex encKey)
          putStrLn ("IV: " ++ binToHex iv)
          putStrLn ("encrypted message: " ++ binToHex encrypted)

          putStrLn ""

          putStrLn "decrypting..."
          let decrypted = open des encKey iv rsa encrypted

          putStrLn ("decrypted message: " ++ decrypted)


binToHex :: String -> String
binToHex bin = concat $ intersperse ":" $ map (printf "%02x" . fromEnum) bin