avoid unnecessary KMS requests during single-part PUT (#9220)

This commit fixes a performance issue caused
by too many calls to the external KMS - i.e.
for single-part PUT requests.

In general, the issue is caused by a sub-optimal
code structure. In particular, when the server
encrypts an object it requests a new data encryption
key from the KMS. With this key it does some key
derivation and encrypts the object content and
ETag.

However, to behave S3-compatible the MinIO server
has to return the plaintext ETag to the client
in case SSE-S3.
Therefore, the server code used to decrypt the
(previously encrypted) ETag again by requesting
the data encryption key (KMS decrypt API) from
the KMS.

This leads to 2 KMS API calls (1 generate key and
1 decrypt key) per PUT operation - while only
one KMS call is necessary.

This commit fixes this by fetching a data key only
once from the KMS and keeping the derived object
encryption key around (for the lifetime of the request).

This leads to a significant performance improvement
w.r.t. to PUT workloads:
```
Operation: PUT
Operations: 161 -> 239
Duration: 28s -> 29s
* Average: +47.56% (+25.8 MiB/s) throughput, +47.56% (+2.6) obj/s
* Fastest: +55.49% (+34.5 MiB/s) throughput, +55.49% (+3.5) obj/s
* 50% Median: +58.24% (+32.8 MiB/s) throughput, +58.24% (+3.3) obj/s
* Slowest: +1.83% (+0.6 MiB/s) throughput, +1.83% (+0.1) obj/s
```

cmd/bucket-handlers.go

@@ -755,7 +755,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 	}
 	rawReader := hashReader
 	pReader := NewPutObjReader(rawReader, nil, nil)
-	var objectEncryptionKey []byte
+	var objectEncryptionKey crypto.ObjectKey
 
 	// Check if bucket encryption is enabled
 	_, encEnabled := globalBucketSSEConfigSys.Get(bucket)
@@ -797,7 +797,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			pReader = NewPutObjReader(rawReader, hashReader, objectEncryptionKey)
+			pReader = NewPutObjReader(rawReader, hashReader, &objectEncryptionKey)
 		}
 	}
 

cmd/encryption-v1.go

@@ -29,6 +29,7 @@ import (
 	"net/http"
 	"path"
 	"strconv"
+	"strings"
 
 	"github.com/minio/minio-go/v6/pkg/encrypt"
 	"github.com/minio/minio/cmd/crypto"
@@ -168,39 +169,39 @@ func rotateKey(oldKey []byte, newKey []byte, bucket, object string, metadata map
 	}
 }
 
-func newEncryptMetadata(key []byte, bucket, object string, metadata map[string]string, sseS3 bool) ([]byte, error) {
+func newEncryptMetadata(key []byte, bucket, object string, metadata map[string]string, sseS3 bool) (crypto.ObjectKey, error) {
 	var sealedKey crypto.SealedKey
 	if sseS3 {
 		if GlobalKMS == nil {
-			return nil, errKMSNotConfigured
+			return crypto.ObjectKey{}, errKMSNotConfigured
 		}
 		key, encKey, err := GlobalKMS.GenerateKey(GlobalKMS.KeyID(), crypto.Context{bucket: path.Join(bucket, object)})
 		if err != nil {
-			return nil, err
+			return crypto.ObjectKey{}, err
 		}
 
 		objectKey := crypto.GenerateKey(key, rand.Reader)
 		sealedKey = objectKey.Seal(key, crypto.GenerateIV(rand.Reader), crypto.S3.String(), bucket, object)
 		crypto.S3.CreateMetadata(metadata, GlobalKMS.KeyID(), encKey, sealedKey)
-		return objectKey[:], nil
+		return objectKey, nil
 	}
 	var extKey [32]byte
 	copy(extKey[:], key)
 	objectKey := crypto.GenerateKey(extKey, rand.Reader)
 	sealedKey = objectKey.Seal(extKey, crypto.GenerateIV(rand.Reader), crypto.SSEC.String(), bucket, object)
 	crypto.SSEC.CreateMetadata(metadata, sealedKey)
-	return objectKey[:], nil
+	return objectKey, nil
 }
 
-func newEncryptReader(content io.Reader, key []byte, bucket, object string, metadata map[string]string, sseS3 bool) (r io.Reader, encKey []byte, err error) {
+func newEncryptReader(content io.Reader, key []byte, bucket, object string, metadata map[string]string, sseS3 bool) (io.Reader, crypto.ObjectKey, error) {
 	objectEncryptionKey, err := newEncryptMetadata(key, bucket, object, metadata, sseS3)
 	if err != nil {
-		return nil, encKey, err
+		return nil, crypto.ObjectKey{}, err
 	}
 
 	reader, err := sio.EncryptReader(content, sio.Config{Key: objectEncryptionKey[:], MinVersion: sio.Version20})
 	if err != nil {
-		return nil, encKey, crypto.ErrInvalidCustomerKey
+		return nil, crypto.ObjectKey{}, crypto.ErrInvalidCustomerKey
 	}
 
 	return reader, objectEncryptionKey, nil
@@ -225,23 +226,24 @@ func setEncryptionMetadata(r *http.Request, bucket, object string, metadata map[
 // EncryptRequest takes the client provided content and encrypts the data
 // with the client provided key. It also marks the object as client-side-encrypted
 // and sets the correct headers.
-func EncryptRequest(content io.Reader, r *http.Request, bucket, object string, metadata map[string]string) (reader io.Reader, objEncKey []byte, err error) {
-	var key []byte
-
+func EncryptRequest(content io.Reader, r *http.Request, bucket, object string, metadata map[string]string) (io.Reader, crypto.ObjectKey, error) {
 	if crypto.S3.IsRequested(r.Header) && crypto.SSEC.IsRequested(r.Header) {
-		return nil, objEncKey, crypto.ErrIncompatibleEncryptionMethod
-	}
-	if crypto.SSEC.IsRequested(r.Header) {
-		key, err = ParseSSECustomerRequest(r)
-		if err != nil {
-			return nil, objEncKey, err
-		}
+		return nil, crypto.ObjectKey{}, crypto.ErrIncompatibleEncryptionMethod
 	}
 	if r.ContentLength > encryptBufferThreshold {
 		// The encryption reads in blocks of 64KB.
 		// We add a buffer on bigger files to reduce the number of syscalls upstream.
 		content = bufio.NewReaderSize(content, encryptBufferSize)
 	}
+
+	var key []byte
+	if crypto.SSEC.IsRequested(r.Header) {
+		var err error
+		key, err = ParseSSECustomerRequest(r)
+		if err != nil {
+			return nil, crypto.ObjectKey{}, err
+		}
+	}
 	return newEncryptReader(content, key, bucket, object, metadata, crypto.S3.IsRequested(r.Header))
 }
 
@@ -634,6 +636,47 @@ func (o *ObjectInfo) DecryptedSize() (int64, error) {
 	return size, nil
 }
 
+// DecryptETag decrypts the ETag that is part of given object
+// with the given object encryption key.
+//
+// However, DecryptETag does not try to decrypt the ETag if
+// it consists of a 128 bit hex value (32 hex chars) and exactly
+// one '-' followed by a 32-bit number.
+// This special case adresses randomly-generated ETags generated
+// by the MinIO server when running in non-compat mode. These
+// random ETags are not encrypt.
+//
+// Calling DecryptETag with a non-randomly generated ETag will
+// fail.
+func DecryptETag(key crypto.ObjectKey, object ObjectInfo) (string, error) {
+	if n := strings.Count(object.ETag, "-"); n > 0 {
+		if n != 1 {
+			return "", errObjectTampered
+		}
+		i := strings.IndexByte(object.ETag, '-')
+		if len(object.ETag[:i]) != 32 {
+			return "", errObjectTampered
+		}
+		if _, err := hex.DecodeString(object.ETag[:32]); err != nil {
+			return "", errObjectTampered
+		}
+		if _, err := strconv.ParseInt(object.ETag[i+1:], 10, 32); err != nil {
+			return "", errObjectTampered
+		}
+		return object.ETag, nil
+	}
+
+	etag, err := hex.DecodeString(object.ETag)
+	if err != nil {
+		return "", err
+	}
+	etag, err = key.UnsealETag(etag)
+	if err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(etag), nil
+}
+
 // For encrypted objects, the ETag sent by client if available
 // is stored in encrypted form in the backend. Decrypt the ETag
 // if ETag was previously encrypted.

cmd/encryption-v1_test.go

@@ -256,6 +256,78 @@ func TestDecryptObjectInfo(t *testing.T) {
 	}
 }
 
+var decryptETagTests = []struct {
+	ObjectKey  crypto.ObjectKey
+	ObjectInfo ObjectInfo
+	ShouldFail bool
+	ETag       string
+}{
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "20000f00f27834c9a2654927546df57f9e998187496394d4ee80f3d9978f85f3c7d81f72600cdbe03d80dc5a13d69354"},
+		ETag:       "8ad3fe6b84bf38489e95c701c84355b6",
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "20000f00f27834c9a2654927546df57f9e998187496394d4ee80f3d9978f85f3c7d81f72600cdbe03d80dc5a13d6935"},
+		ETag:       "",
+		ShouldFail: true, // ETag is not a valid hex value
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "00000f00f27834c9a2654927546df57f9e998187496394d4ee80f3d9978f85f3c7d81f72600cdbe03d80dc5a13d69354"},
+		ETag:       "",
+		ShouldFail: true, // modified ETag
+	},
+
+	// Special tests for ETags that end with a '-x'
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "916516b396f0f4d4f2a0e7177557bec4-1"},
+		ETag:       "916516b396f0f4d4f2a0e7177557bec4-1",
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "916516b396f0f4d4f2a0e7177557bec4-738"},
+		ETag:       "916516b396f0f4d4f2a0e7177557bec4-738",
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "916516b396f0f4d4f2a0e7177557bec4-Q"},
+		ETag:       "",
+		ShouldFail: true, // Q is not a number
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "16516b396f0f4d4f2a0e7177557bec4-1"},
+		ETag:       "",
+		ShouldFail: true, // ETag prefix is not a valid hex value
+	},
+	{
+		ObjectKey:  [32]byte{},
+		ObjectInfo: ObjectInfo{ETag: "16516b396f0f4d4f2a0e7177557bec4-1-2"},
+		ETag:       "",
+		ShouldFail: true, // ETag contains multiple: -
+	},
+}
+
+func TestDecryptETag(t *testing.T) {
+	for i, test := range decryptETagTests {
+		etag, err := DecryptETag(test.ObjectKey, test.ObjectInfo)
+		if err != nil && !test.ShouldFail {
+			t.Fatalf("Test %d: should succeed but failed: %v", i, err)
+		}
+		if err == nil && test.ShouldFail {
+			t.Fatalf("Test %d: should fail but succeeded", i)
+		}
+		if err == nil {
+			if etag != test.ETag {
+				t.Fatalf("Test %d: ETag mismatch: got %s - want %s", i, etag, test.ETag)
+			}
+		}
+	}
+}
+
 // Tests for issue reproduced when getting the right encrypted
 // offset of the object.
 func TestGetDecryptedRange_Issue50(t *testing.T) {

cmd/object-api-utils.go

@@ -773,16 +773,13 @@ func (p *PutObjReader) MD5CurrentHexString() string {
 // NewPutObjReader returns a new PutObjReader and holds
 // reference to underlying data stream from client and the encrypted
 // data reader
-func NewPutObjReader(rawReader *hash.Reader, encReader *hash.Reader, encKey []byte) *PutObjReader {
+func NewPutObjReader(rawReader *hash.Reader, encReader *hash.Reader, key *crypto.ObjectKey) *PutObjReader {
 	p := PutObjReader{Reader: rawReader, rawReader: rawReader}
 
-	if len(encKey) != 0 && encReader != nil {
-		var objKey crypto.ObjectKey
-		copy(objKey[:], encKey)
-		p.sealMD5Fn = sealETagFn(objKey)
+	if key != nil && encReader != nil {
+		p.sealMD5Fn = sealETagFn(*key)
 		p.Reader = encReader
 	}
-
 	return &p
 }
 

cmd/object-handlers.go

@@ -19,8 +19,6 @@ package cmd
 import (
 	"bufio"
 	"context"
-	"crypto/hmac"
-	"encoding/binary"
 	"encoding/hex"
 	"encoding/xml"
 	"io"
@@ -49,7 +47,6 @@ import (
 	iampolicy "github.com/minio/minio/pkg/iam/policy"
 	"github.com/minio/minio/pkg/ioutil"
 	"github.com/minio/minio/pkg/s3select"
-	sha256 "github.com/minio/sha256-simd"
 	"github.com/minio/sio"
 )
 
@@ -905,7 +902,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 			return
 		}
 
-		var oldKey, newKey, objEncKey []byte
+		var oldKey, newKey []byte
+		var objEncKey crypto.ObjectKey
 		sseCopyS3 := crypto.S3.IsEncrypted(srcInfo.UserDefined)
 		sseCopyC := crypto.SSEC.IsEncrypted(srcInfo.UserDefined) && crypto.SSECopy.IsRequested(r.Header)
 		sseC := crypto.SSEC.IsRequested(r.Header)
@@ -995,7 +993,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 				return
 			}
 
-			pReader = NewPutObjReader(rawReader, srcInfo.Reader, objEncKey)
+			pReader = NewPutObjReader(rawReader, srcInfo.Reader, &objEncKey)
 		}
 	}
 
@@ -1355,26 +1353,28 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	var objectEncryptionKey []byte
+	var objectEncryptionKey crypto.ObjectKey
 	if objectAPI.IsEncryptionSupported() {
 		if crypto.IsRequested(r.Header) && !HasSuffix(object, SlashSeparator) { // handle SSE requests
 			if crypto.SSECopy.IsRequested(r.Header) {
 				writeErrorResponse(ctx, w, toAPIError(ctx, errInvalidEncryptionParameters), r.URL, guessIsBrowserReq(r))
 				return
 			}
+
 			reader, objectEncryptionKey, err = EncryptRequest(hashReader, r, bucket, object, metadata)
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
 			info := ObjectInfo{Size: size}
+
 			// do not try to verify encrypted content
 			hashReader, err = hash.NewReader(reader, info.EncryptedSize(), "", "", size, globalCLIContext.StrictS3Compat)
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			pReader = NewPutObjReader(rawReader, hashReader, objectEncryptionKey)
+			pReader = NewPutObjReader(rawReader, hashReader, &objectEncryptionKey)
 		}
 	}
 
@@ -1389,27 +1389,29 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	}
 
 	etag := objInfo.ETag
-	if objInfo.IsCompressed() {
+	switch {
+	case objInfo.IsCompressed():
 		if !strings.HasSuffix(objInfo.ETag, "-1") {
 			etag = objInfo.ETag + "-1"
 		}
-	} else if crypto.IsRequested(r.Header) {
-		etag = getDecryptedETag(r.Header, objInfo, false)
-	}
-	w.Header()[xhttp.ETag] = []string{"\"" + etag + "\""}
-
-	if objectAPI.IsEncryptionSupported() {
-		if crypto.IsEncrypted(objInfo.UserDefined) {
-			switch {
-			case crypto.S3.IsEncrypted(objInfo.UserDefined):
-				w.Header().Set(crypto.SSEHeader, crypto.SSEAlgorithmAES256)
-			case crypto.SSEC.IsRequested(r.Header):
-				w.Header().Set(crypto.SSECAlgorithm, r.Header.Get(crypto.SSECAlgorithm))
-				w.Header().Set(crypto.SSECKeyMD5, r.Header.Get(crypto.SSECKeyMD5))
+	case crypto.IsEncrypted(objInfo.UserDefined):
+		switch {
+		case crypto.S3.IsEncrypted(objInfo.UserDefined):
+			w.Header().Set(crypto.SSEHeader, crypto.SSEAlgorithmAES256)
+			etag, _ = DecryptETag(objectEncryptionKey, ObjectInfo{ETag: etag})
+		case crypto.SSEC.IsEncrypted(objInfo.UserDefined):
+			w.Header().Set(crypto.SSECAlgorithm, r.Header.Get(crypto.SSECAlgorithm))
+			w.Header().Set(crypto.SSECKeyMD5, r.Header.Get(crypto.SSECKeyMD5))
+
+			if len(etag) >= 32 && strings.Count(etag, "-") != 1 {
+				etag = etag[len(etag)-32:]
 			}
 		}
 	}
-
+	// We must not use the http.Header().Set method here because some (broken)
+	// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).
+	// Therefore, we have to set the ETag directly as map entry.
+	w.Header()[xhttp.ETag] = []string{`"` + etag + `"`}
 	writeSuccessResponseHeadersOnly(w)
 
 	// Notify object created event.
@@ -1812,7 +1814,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 	pReader := NewPutObjReader(rawReader, nil, nil)
 
 	isEncrypted := false
-	var objectEncryptionKey []byte
+	var objectEncryptionKey crypto.ObjectKey
 	if objectAPI.IsEncryptionSupported() && !isCompressed {
 		li, lerr := objectAPI.ListObjectParts(ctx, dstBucket, dstObject, uploadID, 0, 1, dstOpts)
 		if lerr != nil {
@@ -1843,19 +1845,15 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 					return
 				}
 			}
-			objectEncryptionKey, err = decryptObjectInfo(key, dstBucket, dstObject, li.UserDefined)
+			key, err = decryptObjectInfo(key, dstBucket, dstObject, li.UserDefined)
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
+			copy(objectEncryptionKey[:], key)
 
-			var partIDbin [4]byte
-			binary.LittleEndian.PutUint32(partIDbin[:], uint32(partID)) // marshal part ID
-
-			mac := hmac.New(sha256.New, objectEncryptionKey) // derive part encryption key from part ID and object key
-			mac.Write(partIDbin[:])
-			partEncryptionKey := mac.Sum(nil)
-			reader, err = sio.EncryptReader(reader, sio.Config{Key: partEncryptionKey})
+			partEncryptionKey := objectEncryptionKey.DerivePartKey(uint32(partID))
+			reader, err = sio.EncryptReader(reader, sio.Config{Key: partEncryptionKey[:]})
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
@@ -1867,7 +1865,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			pReader = NewPutObjReader(rawReader, srcInfo.Reader, objectEncryptionKey)
+			pReader = NewPutObjReader(rawReader, srcInfo.Reader, &objectEncryptionKey)
 		}
 	}
 	srcInfo.PutObjReader = pReader
@@ -1881,7 +1879,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 	}
 
 	if isEncrypted {
-		partInfo.ETag = tryDecryptETag(objectEncryptionKey, partInfo.ETag, crypto.SSEC.IsRequested(r.Header))
+		partInfo.ETag = tryDecryptETag(objectEncryptionKey[:], partInfo.ETag, crypto.SSEC.IsRequested(r.Header))
 	}
 
 	response := generateCopyObjectPartResponse(partInfo.ETag, partInfo.LastModified)
@@ -2069,7 +2067,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 	}
 
 	isEncrypted := false
-	var objectEncryptionKey []byte
+	var objectEncryptionKey crypto.ObjectKey
 	if objectAPI.IsEncryptionSupported() && !isCompressed {
 		var li ListPartsInfo
 		li, err = objectAPI.ListObjectParts(ctx, bucket, object, uploadID, 0, 1, ObjectOptions{})
@@ -2101,25 +2099,21 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 			}
 
 			// Calculating object encryption key
-			objectEncryptionKey, err = decryptObjectInfo(key, bucket, object, li.UserDefined)
+			key, err = decryptObjectInfo(key, bucket, object, li.UserDefined)
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			var partIDbin [4]byte
-			binary.LittleEndian.PutUint32(partIDbin[:], uint32(partID)) // marshal part ID
-
-			mac := hmac.New(sha256.New, objectEncryptionKey) // derive part encryption key from part ID and object key
-			mac.Write(partIDbin[:])
-			partEncryptionKey := mac.Sum(nil)
+			copy(objectEncryptionKey[:], key)
 
+			partEncryptionKey := objectEncryptionKey.DerivePartKey(uint32(partID))
 			in := io.Reader(hashReader)
 			if size > encryptBufferThreshold {
 				// The encryption reads in blocks of 64KB.
 				// We add a buffer on bigger files to reduce the number of syscalls upstream.
 				in = bufio.NewReaderSize(hashReader, encryptBufferSize)
 			}
-			reader, err = sio.EncryptReader(in, sio.Config{Key: partEncryptionKey})
+			reader, err = sio.EncryptReader(in, sio.Config{Key: partEncryptionKey[:]})
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
@@ -2131,7 +2125,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			pReader = NewPutObjReader(rawReader, hashReader, objectEncryptionKey)
+			pReader = NewPutObjReader(rawReader, hashReader, &objectEncryptionKey)
 		}
 	}
 
@@ -2146,7 +2140,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 
 	etag := partInfo.ETag
 	if isEncrypted {
-		etag = tryDecryptETag(objectEncryptionKey, partInfo.ETag, crypto.SSEC.IsRequested(r.Header))
+		etag = tryDecryptETag(objectEncryptionKey[:], partInfo.ETag, crypto.SSEC.IsRequested(r.Header))
 	}
 	w.Header()[xhttp.ETag] = []string{"\"" + etag + "\""}
 

cmd/web-handlers.go

@@ -1137,7 +1137,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 	if objectAPI.IsEncryptionSupported() {
 		if crypto.IsRequested(r.Header) && !HasSuffix(object, SlashSeparator) { // handle SSE requests
 			rawReader := hashReader
-			var objectEncryptionKey []byte
+			var objectEncryptionKey crypto.ObjectKey
 			reader, objectEncryptionKey, err = EncryptRequest(hashReader, r, bucket, object, metadata)
 			if err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
@@ -1150,7 +1150,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 				return
 			}
-			pReader = NewPutObjReader(rawReader, hashReader, objectEncryptionKey)
+			pReader = NewPutObjReader(rawReader, hashReader, &objectEncryptionKey)
 		}
 	}