func main[] : i64
    // XChaCha20
    let key: ptr = str.hex_decode("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f")
    let nonce: ptr = str.hex_decode("000102030405060708090a0b0c0d0e0f1011121314151617")

    let input: str = "Hello, World!"
    let input_len: i64 = str.len(input)

    let ciphertext: ptr = crypto.xchacha20.xor(key, nonce, input, input_len)
    io.println(str.hex_encode(ciphertext, input_len))

    // X25519
    let scalar: ptr = str.hex_decode("a546e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449ac4")
    let point: ptr = str.hex_decode("e6db6867583030db3594c1a424b15f7c726624ec26b3353b10a903a6d0ab1c4c")
    let expected: ptr = str.hex_decode("c3da55379de9c6908e94ea4df28d084f32eccf03491c71f754b4075577a28552")

    let out: ptr = crypto.x25519.scalarmult(scalar, point)

    io.print("Computed: ")
    io.println(str.hex_encode(out, 32))
    io.print("Expected: ")
    io.println(str.hex_encode(expected, 32))

    let base_point: ptr = mem.alloc(32)
    mem.zero(base_point, 32)
    mem.write8(base_point, 9)

    let alice_private: ptr = str.hex_decode("77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a")
    io.print("A_priv: ")
    io.println(str.hex_encode(alice_private, 32))

    let alice_public: ptr = crypto.x25519.scalarmult(alice_private, base_point)
    io.print("A_pub: ")
    io.println(str.hex_encode(alice_public, 32))

    let bob_private: ptr = str.hex_decode("5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6dbddb79b1732920165")
    io.print("B_priv: ")
    io.println(str.hex_encode(bob_private, 32))

    let bob_public: ptr = crypto.x25519.scalarmult(bob_private, base_point)
    io.print("B_pub: ")
    io.println(str.hex_encode(bob_public, 32))

    let alice_shared: ptr = crypto.x25519.scalarmult(alice_private, bob_public)
    io.print("A_shared: ")
    io.println(str.hex_encode(alice_shared, 32))

    let bob_shared: ptr = crypto.x25519.scalarmult(bob_private, alice_public)
    io.print("B_shared: ")
    io.println(str.hex_encode(bob_shared, 32))