package sike

import (
	"bufio"
	"bytes"
	"crypto/rand"
	"encoding/hex"
	"io"
	"math/big"
	"os"
	"strings"
	"testing"
)

var tdata = struct {
	name     string
	katFile  string
	PrA_sidh string
	PkA_sidh string
	PrB_sidh string
	PkB_sidh string
	PkB_sike string
	PrB_sike string
}{
	name:     "SIKEp434",
	katFile:  "etc/PQCkemKAT_374.rsp",
	PrA_sidh: "3A727E04EA9B7E2A766A6F846489E7E7B915263BCEED308BB10FC900",
	PkA_sidh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
	PrB_sidh: "E37BFE55B43B32448F375903D8D226EC94ADBFEA1D2B3536EB987001",
	PkB_sidh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
	PrB_sike: "4B622DE1350119C45A9F2E2EF3DC5DF56A27FCDFCDDAF58CD69B903752D68C200934E160B234E49EDE247601",
	PkB_sike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
}

/* -------------------------------------------------------------------------
   Helpers
   -------------------------------------------------------------------------*/
// Fail if err !=nil. Display msg as an error message
func checkErr(t testing.TB, err error, msg string) {
	t.Helper()
	if err != nil {
		t.Error(msg)
	}
}

// Utility used for running same test with all registered prime fields
type MultiIdTestingFunc func(testing.TB)

// Converts string to private key
func convToPrv(s string, v KeyVariant) *PrivateKey {
	key := NewPrivateKey(v)
	hex, e := hex.DecodeString(s)
	if e != nil {
		panic("non-hex number provided")
	}
	e = key.Import(hex)
	if e != nil {
		panic("Can't import private key")
	}
	return key
}

// Converts string to public key
func convToPub(s string, v KeyVariant) *PublicKey {
	key := NewPublicKey(v)
	hex, e := hex.DecodeString(s)
	if e != nil {
		panic("non-hex number provided")
	}
	e = key.Import(hex)
	if e != nil {
		panic("Can't import public key")
	}
	return key
}

/* -------------------------------------------------------------------------
   Unit tests
   -------------------------------------------------------------------------*/
func TestKeygen(t *testing.T) {
	var keyExp, keyGot [55 * 2 * 3]byte
	alicePrivate := convToPrv(tdata.PrA_sidh, KeyVariant_SIDH_A)
	bobPrivate := convToPrv(tdata.PrB_sidh, KeyVariant_SIDH_B)
	expPubA := convToPub(tdata.PkA_sidh, KeyVariant_SIDH_A)
	expPubB := convToPub(tdata.PkB_sidh, KeyVariant_SIDH_B)

	pubA := NewPublicKey(KeyVariant_SIDH_A)
	alicePrivate.GeneratePublicKey(pubA)
	pubB := NewPublicKey(KeyVariant_SIDH_B)
	bobPrivate.GeneratePublicKey(pubB)

	pubA.Export(keyExp[:])
	expPubA.Export(keyGot[:])
	if !bytes.Equal(keyExp[:], keyGot[:]) {
		t.Fatalf("unexpected value of public key A [\nGot: %X\nExp: %X]\n",
			keyExp, keyGot)
	}

	for i, _ := range keyExp {
		keyExp[i] = 0
		keyGot[i] = 0
	}

	pubB.Export(keyExp[:])
	expPubB.Export(keyGot[:])
	if !bytes.Equal(keyExp[:], keyGot[:]) {
		t.Fatalf("unexpected value of public key B [\nGot: %X\nExp: %X]\n",
			keyGot, keyExp)
	}
}

func TestImportExport(t *testing.T) {
	var err error
	var aBytes, bBytes [110 * 3]byte

	a := NewPublicKey(KeyVariant_SIDH_A)
	b := NewPublicKey(KeyVariant_SIDH_B)

	// Import keys
	aHex, err := hex.DecodeString(tdata.PkA_sidh)
	checkErr(t, err, "invalid hex-number provided")

	err = a.Import(aHex)
	checkErr(t, err, "import failed")

	bHex, err := hex.DecodeString(tdata.PkB_sike)
	checkErr(t, err, "invalid hex-number provided")

	err = b.Import(bHex)
	checkErr(t, err, "import failed")

	a.Export(aBytes[:])
	b.Export(bBytes[:])

	// Export and check if same
	if !bytes.Equal(bBytes[:], bHex) || !bytes.Equal(aBytes[:], aHex) {
		t.Fatalf("export/import failed")
	}

	if (len(bBytes) != b.Size()) || (len(aBytes) != a.Size()) {
		t.Fatalf("wrong size of exported keys")
	}
}

func testPrivateKeyBelowMax(t testing.TB) {
	for variant, keySz := range map[KeyVariant]*DomainParams{
		KeyVariant_SIDH_A: &Params.A,
		KeyVariant_SIDH_B: &Params.B} {

		func(v KeyVariant, dp *DomainParams) {
			var blen = int(dp.SecretByteLen)
			var prv = NewPrivateKey(v)
			var secretBytes = make([]byte, prv.Size())

			// Calculate either (2^e2 - 1) or (2^s - 1); where s=ceil(log_2(3^e3)))
			maxSecertVal := big.NewInt(int64(dp.SecretBitLen))
			maxSecertVal.Exp(big.NewInt(int64(2)), maxSecertVal, nil)
			maxSecertVal.Sub(maxSecertVal, big.NewInt(1))

			// Do same test 1000 times
			for i := 0; i < 1000; i++ {
				err := prv.Generate(rand.Reader)
				checkErr(t, err, "Private key generation")

				// Convert to big-endian, as that's what expected by (*Int)SetBytes()
				prv.Export(secretBytes)
				for i := 0; i < int(blen/2); i++ {
					tmp := secretBytes[i] ^ secretBytes[blen-i-1]
					secretBytes[i] = tmp ^ secretBytes[i]
					secretBytes[blen-i-1] = tmp ^ secretBytes[blen-i-1]
				}
				prvBig := new(big.Int).SetBytes(secretBytes)
				// Check if generated key is bigger then acceptable
				if prvBig.Cmp(maxSecertVal) == 1 {
					t.Error("Generated private key is wrong")
				}
			}
		}(variant, keySz)
	}
}

func testKeyAgreement(t *testing.T, pkA, prA, pkB, prB string) {
	var e error
	var s1, s2 [110 * 3]byte

	// KeyPairs
	alicePublic := convToPub(pkA, KeyVariant_SIDH_A)
	bobPublic := convToPub(pkB, KeyVariant_SIDH_B)
	alicePrivate := convToPrv(prA, KeyVariant_SIDH_A)
	bobPrivate := convToPrv(prB, KeyVariant_SIDH_B)

	// Do actual test
	e = DeriveSecret(s1[:], bobPrivate, alicePublic)
	checkErr(t, e, "derivation s1")
	e = DeriveSecret(s2[:], alicePrivate, bobPublic)
	checkErr(t, e, "derivation s1")

	if !bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("two shared keys: %d, %d do not match", s1, s2)
	}

	// Negative case
	dec, e := hex.DecodeString(tdata.PkA_sidh)
	if e != nil {
		t.FailNow()
	}
	dec[0] = ^dec[0]
	e = alicePublic.Import(dec)
	if e != nil {
		t.FailNow()
	}

	e = DeriveSecret(s1[:], bobPrivate, alicePublic)
	checkErr(t, e, "derivation of s1 failed")
	e = DeriveSecret(s2[:], alicePrivate, bobPublic)
	checkErr(t, e, "derivation of s2 failed")

	if bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("The two shared keys: %d, %d match", s1, s2)
	}
}

func TestDerivationRoundTrip(t *testing.T) {
	var err error
	var s1, s2 [110 * 3]byte

	pubA := NewPublicKey(KeyVariant_SIDH_A)
	prvA := NewPrivateKey(KeyVariant_SIDH_A)
	pubB := NewPublicKey(KeyVariant_SIDH_B)
	prvB := NewPrivateKey(KeyVariant_SIDH_B)

	// Generate private keys
	err = prvA.Generate(rand.Reader)
	checkErr(t, err, "key generation failed")
	err = prvB.Generate(rand.Reader)
	checkErr(t, err, "key generation failed")

	// Generate public keys
	prvA.GeneratePublicKey(pubA)
	prvB.GeneratePublicKey(pubB)

	// Derive shared secret
	err = DeriveSecret(s1[:], prvB, pubA)
	checkErr(t, err, "")

	err = DeriveSecret(s2[:], prvA, pubB)
	checkErr(t, err, "")

	if !bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("Two shared keys: \n%X, \n%X do not match", s1, s2)
	}
}

// encrypt, decrypt, check if input/output plaintext is the same
func TestPKERoundTrip(t *testing.T) {
	// Message to be encrypted
	var msg = make([]byte, Params.MsgLen)
	var ct = make([]byte, kem.CiphertextSize())
	for i, _ := range msg {
		msg[i] = byte(i)
	}

	// Import keys
	pkB := NewPublicKey(KeyVariant_SIKE)
	skB := NewPrivateKey(KeyVariant_SIKE)
	pk_hex, err := hex.DecodeString(tdata.PkB_sike)
	if err != nil {
		t.Fatal(err)
	}
	sk_hex, err := hex.DecodeString(tdata.PrB_sike)
	if err != nil {
		t.Fatal(err)
	}
	if pkB.Import(pk_hex) != nil || skB.Import(sk_hex) != nil {
		t.Error("Import")
	}

	err = encrypt(ct, rand.Reader, pkB, msg[:])
	if err != nil {
		t.Fatal(err)
	}
	var pt [40]byte
	pt_len, err := decrypt(pt[:], skB, ct)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(pt[:pt_len], msg[:]) {
		t.Errorf("Decryption failed \n got : %X\n exp : %X", pt, msg)
	}
}

// Generate key and check if can encrypt
func TestPKEKeyGeneration(t *testing.T) {
	// Message to be encrypted
	var msg = make([]byte, Params.MsgLen)
	var ct = make([]byte, kem.CiphertextSize())
	var err error
	for i, _ := range msg {
		msg[i] = byte(i)
	}

	sk := NewPrivateKey(KeyVariant_SIKE)
	err = sk.Generate(rand.Reader)
	checkErr(t, err, "PEK key generation")
	pk := NewPublicKey(KeyVariant_SIKE)
	sk.GeneratePublicKey(pk)

	// Try to encrypt
	err = encrypt(ct, rand.Reader, pk, msg[:])
	checkErr(t, err, "PEK encryption")
	var pt [40]byte
	pt_len, err := decrypt(pt[:], sk, ct)
	checkErr(t, err, "PEK key decryption")

	if !bytes.Equal(pt[:pt_len], msg[:]) {
		t.Fatalf("Decryption failed \n got : %X\n exp : %X", pt, msg)
	}
}

func TestNegativePKE(t *testing.T) {
	var msg [40]byte
	var err error
	var ct = make([]byte, kem.CiphertextSize())

	// Generate key
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	err = sk.Generate(rand.Reader)
	checkErr(t, err, "key generation")

	sk.GeneratePublicKey(pk)

	// bytelen(msg) - 1
	err = encrypt(ct, rand.Reader, pk, msg[:Params.KemSize+8-1])
	if err == nil {
		t.Fatal("Error hasn't been returned")
	}
	for _, v := range ct {
		if v != 0 {
			t.Fatal("Returned ciphertext must be not changed")
		}
	}

	// KemSize - 1
	var pt [40]byte
	pt_len, err := decrypt(pt[:], sk, msg[:Params.KemSize+8-1])
	if err == nil {
		t.Fatal("Error hasn't been returned")
	}
	if pt_len != 0 {
		t.Fatal("Ciphertext must be nil")
	}
}

func testKEMRoundTrip(t *testing.T, pkB, skB []byte) {
	ct := make([]byte, kem.CiphertextSize())
	ss_e := make([]byte, kem.SharedSecretSize())
	ss_d := make([]byte, kem.SharedSecretSize())
	// Import keys
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	if pk.Import(pkB) != nil || sk.Import(skB) != nil {
		t.Error("Import failed")
	}

	checkErr(t, kem.Encapsulate(ct, ss_e, pk),
		"error: Encapsulation during round-trip")
	checkErr(t, kem.Decapsulate(ss_d, sk, pk, ct),
		"error: Decapsulation during round-trip")

	if !bytes.Equal(ss_e, ss_d) {
		t.Error("Shared secrets from decapsulation and encapsulation differ")
	}
}

func TestKEMRoundTrip(t *testing.T) {
	pk, err := hex.DecodeString(tdata.PkB_sike)
	checkErr(t, err, "public key B not a number")
	sk, err := hex.DecodeString(tdata.PrB_sike)
	checkErr(t, err, "private key B not a number")
	testKEMRoundTrip(t, pk, sk)
}

func TestKEMKeyGeneration(t *testing.T) {
	ct := make([]byte, kem.CiphertextSize())
	ss_e := make([]byte, kem.SharedSecretSize())
	ss_d := make([]byte, kem.SharedSecretSize())

	// Generate key
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	// calculated shared secret
	checkErr(t, kem.Encapsulate(ct, ss_e, pk),
		"encapsulation failed")
	checkErr(t, kem.Decapsulate(ss_d, sk, pk, ct),
		"decapsulation failed")

	if !bytes.Equal(ss_e, ss_d) {
		t.Fatalf("KEM failed \n encapsulated: %X\n decapsulated: %X", ss_d, ss_e)
	}
}

func TestNegativeKEM(t *testing.T) {
	ct := make([]byte, kem.CiphertextSize())
	ss_e := make([]byte, kem.SharedSecretSize())
	ss_d := make([]byte, kem.SharedSecretSize())

	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	checkErr(t, kem.Encapsulate(ct, ss_e, pk),
		"pre-requisite for a test failed")

	ct[0] = ct[0] - 1
	checkErr(t, kem.Decapsulate(ss_d, sk, pk, ct),
		"decapsulation returns error when invalid ciphertext provided")

	if bytes.Equal(ss_e[:], ss_d) {
		// no idea how this could ever happen, but it would be very bad
		t.Error("critical error")
	}

	// Try encapsulating with SIDH key
	pkSidh := NewPublicKey(KeyVariant_SIDH_B)
	prSidh := NewPrivateKey(KeyVariant_SIDH_B)
	err := kem.Encapsulate(ct, ss_e, pkSidh)
	if err == nil {
		t.Error("encapsulation accepts SIDH public key")
	}
	// Try decapsulating with SIDH key
	err = kem.Decapsulate(ss_e, prSidh, pk, ct)
	if err == nil {
		t.Error("decapsulation accepts SIDH private key key")
	}
}

// In case invalid ciphertext is provided, SIKE's decapsulation must
// return same (but unpredictable) result for a given key.
func TestNegativeKEMSameWrongResult(t *testing.T) {
	ct := make([]byte, kem.CiphertextSize())
	ss_e := make([]byte, kem.SharedSecretSize())
	ss_d1 := make([]byte, kem.SharedSecretSize())
	ss_d2 := make([]byte, kem.SharedSecretSize())

	sk := NewPrivateKey(KeyVariant_SIKE)
	pk := NewPublicKey(KeyVariant_SIKE)

	// generate keys
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	checkErr(t, kem.Encapsulate(ct, ss_e, pk),
		"pre-requisite for a test failed")

	// make ciphertext wrong
	ct[0] = ct[0] - 1
	checkErr(t, kem.Decapsulate(ss_d1, sk, pk, ct),
		"pre-requisite for a test failed")

	// second decapsulation must be done with same, but imported private key
	var expSk = make([]byte, sk.Size())
	sk.Export(expSk)

	// creat new private key
	sk = NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Import(expSk),
		"import failed")

	// try decapsulating again. ss2 must be same as ss1 and different than
	// original plaintext
	checkErr(t, kem.Decapsulate(ss_d2, sk, pk, ct),
		"pre-requisite for a test failed")

	if !bytes.Equal(ss_d1, ss_d2) {
		t.Error("decapsulation is insecure")
	}

	if bytes.Equal(ss_e, ss_d1) || bytes.Equal(ss_e, ss_d2) {
		// this test requires that decapsulation returns wrong result
		t.Errorf("test implementation error")
	}
}

func testKeygen(t *testing.T, pk, sk []byte) {
	var pubKeyBytes [110 * 3]byte
	// Import provided private key
	var prvKey = NewPrivateKey(KeyVariant_SIKE)
	if prvKey.Import(sk) != nil {
		panic("sike test: can't load KAT")
	}

	// Generate public key
	pubKey := NewPublicKey(KeyVariant_SIKE)
	prvKey.GeneratePublicKey(pubKey)
	pubKey.Export(pubKeyBytes[:])
	if !bytes.Equal(pubKeyBytes[:], pk) {
		t.Fatalf("KAT keygen form private failed\nExp: %X\nGot: %X\n", pubKeyBytes[:], pk)
	}
}

func TestKeyAgreement(t *testing.T) {
	testKeyAgreement(t, tdata.PkA_sidh, tdata.PrA_sidh, tdata.PkB_sidh, tdata.PrB_sidh)
}

// Same values as in sike_test.cc
func TestDecapsulation(t *testing.T) {

	var sk = [28 + 16]byte{
		0x04, 0x5E, 0x01, 0x42, 0xB8, 0x2F, 0xE1, 0x9A, 0x38, 0x25,
		0x92, 0xE7, 0xDC, 0xBA, 0xF7, 0x1B, 0xB1, 0xFD, 0x34, 0x42,
		0xDB, 0x02, 0xBC, 0x9D, 0x4C, 0xD0, 0x72, 0x34, 0x4D, 0xBD,
		0x06, 0xDF, 0x1C, 0x7D, 0x0A, 0x88, 0xB2, 0x50, 0xC4, 0xF6,
		0xAE, 0xE8, 0x25, 0x01,
	}

	var pk = [330]byte{
		0x6D, 0x8D, 0xF5, 0x7B, 0xCD, 0x47, 0xCA, 0xCB, 0x7A, 0x38,
		0xB7, 0xA6, 0x90, 0xB7, 0x37, 0x03, 0xD4, 0x6F, 0x27, 0x73,
		0x74, 0x17, 0x5A, 0xA4, 0x0D, 0xC6, 0x81, 0xAD, 0xDB, 0xF7,
		0x18, 0xB2, 0x3C, 0x30, 0xCF, 0xAA, 0x08, 0x11, 0x91, 0xCC,
		0x27, 0x4E, 0xF1, 0xA6, 0xB7, 0xDA, 0xD2, 0xCF, 0x99, 0x7F,
		0xF7, 0xE1, 0xD0, 0xCE, 0x00, 0xD2, 0x4B, 0xA4, 0x33, 0xB4,
		0x87, 0x01, 0x3F, 0x02, 0xF7, 0xF9, 0xDE, 0xC3, 0x60, 0x62,
		0xDA, 0x3F, 0x74, 0xA9, 0x44, 0xBE, 0x19, 0xD5, 0x03, 0x2A,
		0x79, 0x8C, 0xA7, 0xFF, 0xEA, 0xB3, 0xBB, 0xB5, 0xD4, 0x1D,
		0x8F, 0x92, 0xCE, 0x62, 0x6E, 0x99, 0x24, 0xD7, 0x57, 0xFA,
		0xCD, 0xB6, 0xE2, 0x8E, 0xFD, 0x22, 0x0E, 0x31, 0x21, 0x01,
		0x8D, 0x79, 0xF8, 0x3E, 0x27, 0xEC, 0x43, 0x40, 0xDB, 0x82,
		0xE5, 0xEB, 0x6C, 0x97, 0x66, 0x29, 0x15, 0x68, 0xB7, 0x4D,
		0x84, 0xD1, 0x8A, 0x0B, 0x12, 0x36, 0x2C, 0x0C, 0x0A, 0x6E,
		0x4E, 0xDE, 0xA5, 0x8A, 0xDE, 0x77, 0xDD, 0x70, 0x49, 0x73,
		0xAC, 0x27, 0x6D, 0x8D, 0x25, 0x9A, 0xE4, 0x25, 0xE8, 0x95,
		0x8F, 0xFE, 0x90, 0x3B, 0x00, 0x69, 0x20, 0xE8, 0x7C, 0xA5,
		0xF5, 0x79, 0xC0, 0x61, 0x51, 0x91, 0x35, 0x25, 0x3F, 0x17,
		0x2F, 0x70, 0x73, 0xF0, 0x89, 0xB5, 0xC8, 0x25, 0xB8, 0xE5,
		0x7E, 0x34, 0xDD, 0x11, 0xE5, 0xD6, 0xC3, 0xD5, 0x29, 0x89,
		0xC6, 0x2C, 0x99, 0x53, 0x1D, 0x2C, 0x77, 0xB0, 0xB6, 0xA1,
		0xBD, 0x79, 0xFB, 0x4A, 0xC2, 0x48, 0x4C, 0x62, 0x51, 0x00,
		0xE3, 0x91, 0x2A, 0xCB, 0x84, 0x03, 0x5D, 0x2D, 0xC8, 0x33,
		0xE9, 0x14, 0xBF, 0x74, 0x21, 0xBC, 0xF4, 0x76, 0xE5, 0x42,
		0xB8, 0xBD, 0xE2, 0xE7, 0x20, 0x95, 0x54, 0xF2, 0xED, 0xC0,
		0x79, 0x38, 0x1E, 0xD2, 0xEA, 0x1A, 0x63, 0x85, 0xE7, 0x3A,
		0xDA, 0xAD, 0xAB, 0x1B, 0x1E, 0x19, 0x9E, 0x73, 0xD0, 0x10,
		0x2E, 0x38, 0xAC, 0x8B, 0x00, 0x6A, 0x30, 0x2C, 0x3D, 0x70,
		0x8E, 0x39, 0x6D, 0xC0, 0x12, 0x61, 0x7D, 0x2A, 0x0A, 0x04,
		0x95, 0x8E, 0x09, 0x3C, 0x7B, 0xEC, 0x2E, 0xBC, 0xE8, 0xE8,
		0xE8, 0x37, 0x29, 0xC4, 0x7E, 0x76, 0x48, 0xB9, 0x3B, 0x72,
		0xE5, 0x99, 0x9B, 0xF9, 0xE3, 0x99, 0x72, 0x3F, 0x35, 0x29,
		0x85, 0xE0, 0xC8, 0xBF, 0xB1, 0x6B, 0xB1, 0x6E, 0x72, 0x00,
	}

	var ct = [330 + 16]byte{
		0x7C, 0xAB, 0x4E, 0x65, 0x2E, 0xBA, 0xD2, 0xBD, 0x8B, 0x66,
		0xCA, 0x2B, 0xA8, 0xF9, 0xEF, 0xE2, 0xFD, 0x2E, 0xCA, 0x83,
		0xE9, 0xCF, 0x50, 0x63, 0x7B, 0x5C, 0x3D, 0xA5, 0xE7, 0xF5,
		0x9F, 0x73, 0xAC, 0xC8, 0xE4, 0x85, 0xFC, 0x05, 0xCD, 0xED,
		0x03, 0x25, 0x02, 0xA4, 0xF5, 0x57, 0x4A, 0x76, 0x3C, 0xDE,
		0x76, 0x52, 0xD0, 0x1B, 0x01, 0xA3, 0xD3, 0xB1, 0x8E, 0xC6,
		0xE1, 0x54, 0x3F, 0x9B, 0xA9, 0xB6, 0x9B, 0x1A, 0xED, 0x62,
		0xB5, 0x7A, 0x58, 0xFB, 0xAC, 0xF2, 0xBD, 0xE6, 0x95, 0x0B,
		0xED, 0x3A, 0x5D, 0x34, 0xB0, 0x54, 0x2D, 0xEF, 0xA9, 0xA7,
		0xA3, 0xA8, 0xD2, 0xA1, 0x8B, 0x96, 0xFA, 0x8F, 0xDD, 0x2E,
		0xE4, 0x93, 0x82, 0x97, 0x19, 0x72, 0xC7, 0x7E, 0x50, 0x00,
		0x8A, 0xE0, 0x0C, 0x5A, 0x94, 0xB2, 0xE1, 0xC3, 0xA5, 0x4D,
		0x92, 0x97, 0xA2, 0x59, 0x97, 0xBC, 0xB9, 0x7F, 0x27, 0x92,
		0xA7, 0x7F, 0x5A, 0x7B, 0x8D, 0x24, 0xFF, 0x9A, 0x99, 0xDB,
		0xDB, 0xE1, 0x5B, 0xD2, 0x10, 0x34, 0x2D, 0x45, 0xA5, 0xE5,
		0x99, 0x7F, 0xFE, 0x02, 0xCC, 0x57, 0x7A, 0x3A, 0xAB, 0xB3,
		0x27, 0xE1, 0x55, 0x70, 0x01, 0x3D, 0xC8, 0xAB, 0x90, 0xC6,
		0x8F, 0x63, 0x8B, 0x30, 0x6F, 0xA1, 0xDC, 0x91, 0xE5, 0x25,
		0xDF, 0x9A, 0x68, 0x05, 0xC2, 0xD4, 0x13, 0x64, 0xAA, 0xEF,
		0x21, 0x63, 0x5E, 0xFF, 0x41, 0xFD, 0xF3, 0x92, 0x76, 0xA6,
		0x09, 0x90, 0xBD, 0x65, 0x56, 0xC9, 0x6D, 0x41, 0xA7, 0x9E,
		0xC7, 0x15, 0xBF, 0xE1, 0x2D, 0xB0, 0x96, 0x26, 0x21, 0x01,
		0x60, 0x54, 0x71, 0x56, 0xD9, 0xA2, 0x9B, 0xD2, 0x21, 0x9C,
		0xD9, 0x0F, 0xF8, 0x5F, 0xC4, 0xF4, 0xF6, 0x8E, 0xCA, 0x87,
		0x7B, 0x7A, 0xDE, 0x28, 0x05, 0x3F, 0x3F, 0xE7, 0xDA, 0x3B,
		0x56, 0x64, 0xE0, 0x8D, 0xEB, 0x4A, 0x54, 0x88, 0x05, 0x4C,
		0x5E, 0x99, 0x45, 0x8C, 0x65, 0x8A, 0x6E, 0x2D, 0x53, 0x1C,
		0x9B, 0x44, 0xA7, 0xEF, 0x01, 0xF8, 0x31, 0x4D, 0x31, 0xE3,
		0x75, 0x7B, 0x5F, 0x79, 0x5F, 0xE7, 0x47, 0x4C, 0x08, 0x86,
		0x84, 0xC8, 0x84, 0x48, 0x89, 0x89, 0x5F, 0x7F, 0x92, 0x68,
		0x2E, 0x9F, 0xBA, 0x46, 0x6D, 0x34, 0x93, 0x86, 0xE4, 0xEA,
		0xE6, 0x1F, 0xF8, 0xE1, 0x94, 0xFF, 0x6E, 0xB6, 0x8D, 0x46,
		0x64, 0xF0, 0xE3, 0xB7, 0x84, 0x0A, 0x5B, 0xE2, 0xC4, 0x01,
		0x6E, 0xA5, 0xB8, 0xFA, 0xA5, 0x5A, 0x1C, 0x2D, 0xF6, 0x81,
		0xC2, 0x44, 0x81, 0x5B, 0x00, 0x17,
	}
	var ss_exp = [16]byte{
		0xCB, 0x9C, 0x6B, 0x0A, 0x64, 0x95, 0x32, 0xA7, 0x35, 0x4E,
		0xE5, 0x14, 0xC8, 0xB7, 0x82, 0xB6,
	}

	var prvObj = NewPrivateKey(KeyVariant_SIKE)
	var pubObj = NewPublicKey(KeyVariant_SIKE)

	if pubObj.Import(pk[:]) != nil || prvObj.Import(sk[:]) != nil {
		t.Error("Can't import one of the keys")
	}

	res := make([]byte, kem.SharedSecretSize())
	checkErr(t, kem.Decapsulate(res, prvObj, pubObj, ct[:]),
		"error: Decapsulation failed")

	if !bytes.Equal(ss_exp[:], res) {
		t.Error("Wrong decapsulation result")
	}
}

func readAndCheckLine(r *bufio.Reader) []byte {
	// Read next line from buffer
	line, isPrefix, err := r.ReadLine()
	if err != nil || isPrefix {
		panic("Wrong format of input file")
	}

	// Function expects that line is in format "KEY = HEX_VALUE". Get
	// value, which should be a hex string
	hexst := strings.Split(string(line), "=")[1]
	hexst = strings.TrimSpace(hexst)
	// Convert value to byte string
	ret, err := hex.DecodeString(hexst)
	if err != nil {
		panic("Wrong format of input file")
	}
	return ret
}

func TestKAT(t *testing.T) {
	ssGot := make([]byte, kem.SharedSecretSize())
	testDecapsulation := func(t *testing.T, pk, sk, ct, ssExpected []byte) {
		var pubKey = NewPublicKey(KeyVariant_SIKE)
		var prvKey = NewPrivateKey(KeyVariant_SIKE)
		if pubKey.Import(pk) != nil || prvKey.Import(sk) != nil {
			panic("sike test: can't load KAT")
		}

		err := kem.Decapsulate(ssGot, prvKey, pubKey, ct)
		if err != nil {
			panic("sike test: can't perform degcapsulation KAT")
		}

		if (err != nil) || !bytes.Equal(ssGot, ssExpected) {
			t.Fatalf("KAT decapsulation failed\n")
		}
	}
	f, err := os.Open(tdata.katFile)
	if err != nil {
		t.Fatal(err)
	}

	r := bufio.NewReader(f)
	for {
		line, isPrefix, err := r.ReadLine()
		if err != nil || isPrefix {
			if err == io.EOF {
				break
			} else {
				t.Fatal(err)
			}
		}
		if len(strings.TrimSpace(string(line))) == 0 || line[0] == '#' {
			continue
		}

		// count
		_ = strings.Split(string(line), "=")[1]
		// seed
		_ = readAndCheckLine(r)
		// pk
		pk := readAndCheckLine(r)
		// sk (secret key in test vector is concatenation of
		// MSG + SECRET_BOB_KEY + PUBLIC_BOB_KEY. We use only MSG+SECRET_BOB_KEY
		sk := readAndCheckLine(r)
		sk = sk[:Params.MsgLen+int(Params.B.SecretByteLen)]
		// ct
		ct := readAndCheckLine(r)
		// ss
		ss := readAndCheckLine(r)
		testKeygen(t, pk, sk)
		testDecapsulation(t, pk, sk, ct, ss)
		testKEMRoundTrip(t, pk, sk)
	}
}

/* -------------------------------------------------------------------------
Benchmarking
-------------------------------------------------------------------------*/

func BenchmarkKeygen(b *testing.B) {
	pk := NewPublicKey(KeyVariant_SIKE)
	prv := NewPrivateKey(KeyVariant_SIKE)
	prv.Generate(rand.Reader)

	for n := 0; n < b.N; n++ {
		prv.GeneratePublicKey(pk)
	}
}

func BenchmarkEncaps(b *testing.B) {
	pub := NewPublicKey(KeyVariant_SIKE)
	prv := NewPrivateKey(KeyVariant_SIKE)

	if prv.Generate(rand.Reader) != nil {
		b.FailNow()
	}
	prv.GeneratePublicKey(pub)

	var ct [16 + 330]byte
	var ss [16]byte

	for n := 0; n < b.N; n++ {
		kem.Reset()
		kem.Encapsulate(ct[:], ss[:], pub)
	}
}

func BenchmarkDecaps(b *testing.B) {
	var ct [16 + 330]byte
	var ss [16]byte

	pkA := NewPublicKey(KeyVariant_SIKE)
	prvA := NewPrivateKey(KeyVariant_SIKE)
	pkB := NewPublicKey(KeyVariant_SIKE)
	prvB := NewPrivateKey(KeyVariant_SIKE)

	if prvA.Generate(rand.Reader) != nil || prvB.Generate(rand.Reader) != nil {
		b.FailNow()
	}

	prvA.GeneratePublicKey(pkA)
	prvB.GeneratePublicKey(pkB)

	err := kem.Encapsulate(ct[:], ss[:], pkA)
	if err != nil {
		b.FailNow()
	}

	for n := 0; n < b.N; n++ {
		kem.Decapsulate(ss[:], prvA, pkB, ct[:])
	}
}

var kem KEM

func init() {
	kem.Allocate(rand.Reader)
}