}
	var (
		sealingKey   [32]byte
		encryptedKey bytes.Buffer
	)
	mac := hmac.New(sha256.New, extKey)
	mac.Write(iv[:])
	mac.Write([]byte(domain))
	mac.Write([]byte(SealAlgorithm))
	mac.Write([]byte(path.Join(bucket, object))) // use path.Join for canonical 'bucket/object'
	mac.Sum(sealingKey[:0])

		algorithm = algorithmAESGCM
	} else {
		algorithm = algorithmChaCha20Poly1305
	}

	var aead cipher.AEAD
	switch algorithm {
	case algorithmAESGCM:
		mac := hmac.New(sha256.New, kms.key)
		mac.Write(iv)
		sealingKey := mac.Sum(nil)

		var block cipher.Block
		block, err = aes.NewCipher(sealingKey)
		if err != nil {
			return DEK{}, err
		}
		aead, err = cipher.NewGCM(block)

#cgo CFLAGS: -x objective-c
#cgo LDFLAGS: -framework CoreFoundation -framework Security
#include <TargetConditionals.h>
#include <CoreFoundation/CoreFoundation.h>
#include <Security/Security.h>
#if TARGET_OS_IPHONE == 0 && __MAC_OS_X_VERSION_MAX_ALLOWED < 101200
  typedef CFStringRef SecKeyAlgorithm;
  static CFDataRef SecKeyCreateSignature(SecKeyRef key, SecKeyAlgorithm algorithm, CFDataRef dataToSign, CFErrorRef *error){return NULL;}

#cgo CFLAGS: -x objective-c
#cgo LDFLAGS: -framework CoreFoundation -framework Security
#include <TargetConditionals.h>
#include <CoreFoundation/CoreFoundation.h>
#include <Security/Security.h>
#if TARGET_OS_IPHONE == 0 && __MAC_OS_X_VERSION_MAX_ALLOWED < 101200
  typedef CFStringRef SecKeyAlgorithm;
  static CFDataRef SecKeyCreateSignature(SecKeyRef key, SecKeyAlgorithm algorithm, CFDataRef dataToSign, CFErrorRef *error){return NULL;}

		shouldFail: false,
	},
	{
		header:     http.Header{crypto.MetaAlgorithm: []string{crypto.InsecureSealAlgorithm}},
		shouldFail: false,
	},
	{
		header:     http.Header{crypto.MetaSealedKeySSEC: []string{"mac"}},
		shouldFail: false,
	},
	{
		header:     http.Header{ReservedMetadataPrefix + "Key": []string{"value"}},
		shouldFail: true,
	},
}

func TestContainsReservedMetadata(t *testing.T) {

#cgo CFLAGS: -x objective-c
#cgo LDFLAGS: -framework CoreFoundation -framework Security
#include <TargetConditionals.h>
#include <CoreFoundation/CoreFoundation.h>
#include <Security/Security.h>
#if TARGET_OS_IPHONE == 0 && __MAC_OS_X_VERSION_MAX_ALLOWED < 101200
  typedef CFStringRef SecKeyAlgorithm;
  static CFDataRef SecKeyCreateSignature(SecKeyRef key, SecKeyAlgorithm algorithm, CFDataRef dataToSign, CFErrorRef *error){return NULL;}