func ConstantTimeEq(x, y int32) int {
	return int((uint64(uint32(x^y)) - 1) >> 63)
}

// ConstantTimeCopy copies the contents of y into x (a slice of equal length)
// if v == 1. If v == 0, x is left unchanged. Its behavior is undefined if v
// takes any other value.
func ConstantTimeCopy(v int, x, y []byte) {
	if len(x) != len(y) {
		panic("subtle: slices have different lengths")
	}

	xmask := byte(v - 1)

	}
	if v == 1 {
		copy(x, y)
	}
	return x
}

func constantTimeCopyWrapper(v int, x, y []byte) []byte {
	if len(x) > len(y) {
		x = x[0:len(y)]
	} else {
		y = y[0:len(x)]
	}
	v &= 1
	ConstantTimeCopy(v, x, y)
	return x
}

func TestConstantTimeCopy(t *testing.T) {
	err := quick.CheckEqual(constantTimeCopyWrapper, makeCopy, nil)
	if err != nil {
		t.Error(err)
	}
}

		// This should be impossible because decryptPKCS1v15 always
		// returns the full slice.
		return ErrDecryption
	}

	valid &= subtle.ConstantTimeEq(int32(len(em)-index), int32(len(key)))
	subtle.ConstantTimeCopy(valid, key, em[len(em)-len(key):])
	return nil
}

// decryptPKCS1v15 decrypts ciphertext using priv. It returns one or zero in
// valid that indicates whether the plaintext was correctly structured.

	J := sha3.NewShake256()
	J.Write(z)
	J.Write(c[:])
	Kout := make([]byte, SharedKeySize)
	J.Read(Kout)
	var cc [CiphertextSize]byte
	c1 := pkeEncrypt(&cc, &dk.encryptionKey, (*[32]byte)(m), r)

	subtle.ConstantTimeCopy(subtle.ConstantTimeCompare(c[:], c1), Kout, Kprime)
	return Kout
}

// parseDK parses a decryption key from its encoded form.
//
// It implements the computation of s from K-PKE.Decrypt according to FIPS 203

		{"Sum384", Func, 2},
		{"Sum512", Func, 2},
		{"Sum512_224", Func, 5},
		{"Sum512_256", Func, 5},
	},
	"crypto/subtle": {
		{"ConstantTimeByteEq", Func, 0},
		{"ConstantTimeCompare", Func, 0},
		{"ConstantTimeCopy", Func, 0},
		{"ConstantTimeEq", Func, 0},
		{"ConstantTimeLessOrEq", Func, 2},
		{"ConstantTimeSelect", Func, 0},
		{"XORBytes", Func, 20},
	},
	"crypto/tls": {

pkg crypto/sha512, func New384() hash.Hash
pkg crypto/subtle, func ConstantTimeByteEq(uint8, uint8) int
pkg crypto/subtle, func ConstantTimeCompare([]uint8, []uint8) int
pkg crypto/subtle, func ConstantTimeCopy(int, []uint8, []uint8)
pkg crypto/subtle, func ConstantTimeEq(int32, int32) int
pkg crypto/subtle, func ConstantTimeSelect(int, int, int) int
pkg crypto/tls, const NoClientCert ClientAuthType