kyber.go

package main

// Based on examples at https://github.com/cloudflare/circl/tree/master/kem/kyber

import (
	"github.com/cloudflare/circl/kem/schemes"

	"encoding/hex"

	"math/rand"

	"time"

	"C"
)

//export genKYBER
func genKYBER(schem *C.char, role *C.char) *C.char {

	scheme := schemes.ByName(C.GoString(schem)) //Kyber512 by default

	rand.Seed(time.Now().UnixNano())

	//Prepare byte buffers
	//40 bytes - sender, 20-bytes recepient

	if C.GoString(role) == "sender" {

		seed := make([]byte, scheme.SeedSize())

		//Fill seed
		rand.Read(seed)

		pk, sk := scheme.DeriveKeyPair(seed)

		pubBytes, _ := pk.MarshalBinary()

		secretBytes, _ := sk.MarshalBinary()

		return C.CString(hex.EncodeToString(seed) + ":" + hex.EncodeToString(pubBytes) + ":" + hex.EncodeToString(secretBytes))

	} else {

		seed := make([]byte, scheme.EncapsulationSeedSize())

		//Fill seed
		rand.Read(seed)

		return C.CString(hex.EncodeToString(seed))

	}

}

//export getSharedKYBERAsSender
func getSharedKYBERAsSender(schem *C.char, hexPrivateKey *C.char, hexCipherText *C.char) *C.char {

	scheme := schemes.ByName(C.GoString(schem)) //Kyber512 KEM by default

	privBytes, _ := hex.DecodeString(C.GoString(hexPrivateKey))

	privK, _ := scheme.UnmarshalBinaryPrivateKey(privBytes)

	//Derive Alice(sender,initiator of handshake) keypair(secretkey need only)

	cipherText, _ := hex.DecodeString(C.GoString(hexCipherText))

	shared, _ := scheme.Decapsulate(privK, cipherText)

	return C.CString(hex.EncodeToString(shared))

}

//export getSharedKYBERAsRecepient
func getSharedKYBERAsRecepient(schem *C.char, hexSeed *C.char, hexSenderPubKey *C.char) *C.char {

	scheme := schemes.ByName(C.GoString(schem)) //Kyber512 by default

	senderPubKey, _ := hex.DecodeString(C.GoString(hexSenderPubKey))

	//Bob receive shared via Alice pubkey
	//EncapsulateDeterministically generates a shared key shared for the public
	//key deterministically from the given seed and encapsulates it into
	//a ciphertext cipherText. If unsure, you're better off using Encapsulate()
	pubK, _ := scheme.UnmarshalBinaryPublicKey(senderPubKey)

	seed, _ := hex.DecodeString(C.GoString(hexSeed))

	cipherText, shared, _ := scheme.EncapsulateDeterministically(pubK, seed)

	return C.CString(hex.EncodeToString(shared) + ":" + hex.EncodeToString(cipherText))

}

func main() {}