How to symmetric encrypt a file in F#?

Question

How to symmetric encrypt a file in F# for tcp transmission?

Answer 1

As in any of the MSDN examples for System.Security.Cryptography

Transposing this example to F# should be fairly trivial.

Key exchange is, as always, something that the system design needs to specify, not random people on a forum.

Answer 2

would like to specify the password (key)

but password is not the valid size for this algorithm, 

tried to

aesCSP.KeySize <- 8

but also same error

let aesCSP = new AesCryptoServiceProvider();
        aesCSP.Key <- encoding.GetBytes("shanshan")
        //aesCSP.GenerateKey();
        aesCSP.GenerateIV();

assume there is no third party to tell the key, how to set the key itself

Answer 3

solved by Rfc2898DeriveBytes

Answer 4

The input data is not a complete block.

what does this error mean?

let rec mainLoop (stream: NetworkStream) (msg: string) =
		...
			if !processing = true && msg.StartsWith("start") = false && msg.StartsWith("end") = false then
                        try
                            let encoding=new System.Text.UTF8Encoding()
                            let decryptedmsg = DecryptBytes(this.aesCSP, encoding.GetBytes(msg))
                            filepacket := !filepacket & decryptedmsg
                        with
                            | ex -> Console.WriteLine(ex.Message.ToString())

member this.aesCSP with get() = let encoding=new System.Text.UTF8Encoding()
                                    let AesCSP = new AesCryptoServiceProvider();
                                    //create the initial salt 
                                    let salt = Encoding.Default.GetBytes("shanshan");
                                    //create the key generator
                                    let keyGenerator = new Rfc2898DeriveBytes("demo", salt);
                                    //create the secret key 128-bit long 
                                    let key = keyGenerator.GetBytes(16);
                                    AesCSP.Key <- key
                                    AesCSP.GenerateIV()
                                    AesCSP