Program.fs

open System
open System.Diagnostics
open System.Runtime.InteropServices
open FSharp.Core

module Native =
    let [<Literal>] DllName = "example_c/libaesxts"
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    // int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key, unsigned char *iv, unsigned char *ciphertext);
    extern int encrypt(byte[] plaintext, int length, byte[] key, byte[] iv, byte[] ciphertext)
 
    // int decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *key, unsigned char *iv, unsigned char *plaintext);
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern int decrypt(byte[] ciphertext, int length, byte[] key, byte[] iv, byte[] plaintext)
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    // void cleanup(void);
    extern unit cleanup()

module Native_Zig =
    let [<Literal>] DllName = "example_zig/libsimplemath"
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern int add(int a, int b)
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern int mult(int a, int b)
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern unit ziggZaggTest()

module Native_Swift =
    let [<Literal>] DllName = "example_swift/libfunc"
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern int advanced_random(int num, int num2)
    
    [<DllImport(DllName, CallingConvention=CallingConvention.Cdecl)>]
    extern unit say_hello()

let dataString =  "Calling C from F#"

printfn $"Will encode :'{dataString}'"

let data = dataString |> System.Text.Encoding.UTF8.GetBytes

let key =  "MDEyMzQ1Njc4OTAxMjM0NTY3ODkwMTIzNDU2Nzg5MDEyMzQ1Njc4OTAxMjM0NTY3ODkwMTIzNDU2Nzg5MDEyMw=="
let key_data = Convert.FromBase64String key
let iv = "MDEyMzQ1Njc4OTAxMjM0NQ=="
let iv_data = Convert.FromBase64String iv

printfn $"Encryption key:'{key}', initialization vector: '{iv}'"

//Buffer for ciphertext. Ensure the buffer is long enough for the
// ciphertext which may be longer than the plaintext, dependant on the
// algorithm and mode
let mutable ciphertext = Array.zeroCreate<byte> (data.Length * 2)

let sw = Stopwatch.StartNew()
let ciphertext_len = Native.encrypt(data, data.Length, key_data, iv_data, ciphertext)
sw.Stop()
let hex_ciphertext = BitConverter.ToString(ciphertext).Replace("-","")
printfn $"Ciphertext[{ciphertext_len}]: {hex_ciphertext} - encrypted in {sw.ElapsedMilliseconds}ms"

let mutable plaintext = Array.zeroCreate<byte> (ciphertext_len)
let sw_decrypt = Stopwatch.StartNew()
let plaintext_len =  Native.decrypt(ciphertext, ciphertext_len, key_data, iv_data, plaintext)
sw_decrypt.Stop()
printfn $"Plaintext[{plaintext_len}]: {System.Text.Encoding.UTF8.GetString(plaintext)} - decrypted in {sw.ElapsedMilliseconds}ms"

Native.cleanup()


// Commented out Zig & Swift code because it's much more difficult to compile than C (because of additional tools needed)


// printfn $"Zig add 5 + 6 = {Native_Zig.add (5,6)} , mult 11 * 42 = {Native_Zig.mult (11,42)}"

// printfn "Zig zagg test"
// Native_Zig.ziggZaggTest()

// Native_Swift.say_hello()
// printfn $"Random number from Swift: {Native_Swift.advanced_random(1,100)}"