Fix SSE-S3 copy: preserve encryption metadata and set chunk SSE type (#7598)

* Fix SSE-S3 copy: preserve encryption metadata and set chunk SSE type

Fixes GitHub #7562: Copying objects between encrypted buckets was failing.

Root causes:
1. processMetadataBytes was re-adding SSE headers from source entry, undoing
   the encryption header filtering. Now uses dstEntry.Extended which is
   already filtered.

2. SSE-S3 streaming copy returned nil metadata. Now properly generates and
   returns SSE-S3 destination metadata (SeaweedFSSSES3Key, AES256 header)
   via ExecuteStreamingCopyWithMetadata.

3. Chunks created during streaming copy didn't have SseType set. Now sets
   SseType and per-chunk SseMetadata with chunk-specific IVs for SSE-S3,
   enabling proper decryption on GetObject.

* Address review: make SSE-S3 metadata serialization failures fatal errors

- In executeEncryptCopy: return error instead of just logging if
  SerializeSSES3Metadata fails
- In createChunkFromData: return error if chunk SSE-S3 metadata
  serialization fails

This ensures objects/chunks are never created without proper encryption
metadata, preventing unreadable/corrupted data.

* fmt

* Refactor: reuse function names instead of creating WithMetadata variants

- Change ExecuteStreamingCopy to return (*EncryptionSpec, error) directly
- Remove ExecuteStreamingCopyWithMetadata wrapper
- Change executeStreamingReencryptCopy to return (*EncryptionSpec, error)
- Remove executeStreamingReencryptCopyWithMetadata wrapper
- Update callers to ignore encryption spec with _ where not needed

* Add TODO documenting large file SSE-S3 copy limitation

The streaming copy approach encrypts the entire stream with a single IV
but stores data in chunks with per-chunk IVs. This causes decryption
issues for large files. Small inline files work correctly.

This is a known architectural issue that needs separate work to fix.

* Use chunk-by-chunk encryption for SSE-S3 copy (consistent with SSE-C/SSE-KMS)

Instead of streaming encryption (which had IV mismatch issues for multi-chunk
files), SSE-S3 now uses the same chunk-by-chunk approach as SSE-C and SSE-KMS:

1. Extended copyMultipartCrossEncryption to handle SSE-S3:
   - Added SSE-S3 source decryption in copyCrossEncryptionChunk
   - Added SSE-S3 destination encryption with per-chunk IVs
   - Added object-level metadata generation for SSE-S3 destinations

2. Updated routing in executeEncryptCopy/executeDecryptCopy/executeReencryptCopy
   to use copyMultipartCrossEncryption for all SSE-S3 scenarios

3. Removed streaming copy functions (shouldUseStreamingCopy,
   executeStreamingReencryptCopy) as they're no longer used

4. Added large file (1MB) integration test to verify chunk-by-chunk copy works

This ensures consistent behavior across all SSE types and fixes data corruption
that occurred with large files in the streaming copy approach.

* fmt

* fmt

* Address review: fail explicitly if SSE-S3 metadata is missing

Instead of silently ignoring missing SSE-S3 metadata (which could create
unreadable objects), now explicitly fail the copy operation with a clear
error message if:
- First chunk is missing
- First chunk doesn't have SSE-S3 type
- First chunk has empty SSE metadata
- Deserialization fails

* Address review: improve comment to reflect full scope of chunk creation

* Address review: fail explicitly if baseIV is empty for SSE-S3 chunk encryption

If DestinationIV is not set when encrypting SSE-S3 chunks, the chunk would
be created without SseMetadata, causing GetObject decryption to fail later.
Now fails explicitly with a clear error message.

Note: calculateIVWithOffset returns ([]byte, int) not ([]byte, error) - the
int is a skip amount for intra-block alignment, not an error code.

* Address review: handle 0-byte files in SSE-S3 copy

For 0-byte files, there are no chunks to get metadata from. Generate an IV
for the object-level metadata to ensure even empty files are properly marked
as SSE-S3 encrypted.

Also validate that we don't have a non-empty file with no chunks (which
would indicate an internal error).

4 files changed, 244 insertions, 115 deletions

diff --git a/test/s3/sse/s3_sse_integration_test.go b/test/s3/sse/s3_sse_integration_test.go
index 7b939ea76..4b7eb0ddc 100644
--- a/test/s3/sse/s3_sse_integration_test.go
+++ b/test/s3/sse/s3_sse_integration_test.go
@@ -2082,6 +2082,78 @@ func TestCopyToBucketDefaultEncryptedRegression(t *testing.T) {
 		require.NoError(t, err, "Failed to read object")
 		assertDataEqual(t, testData, data, "Data mismatch")
 	})
+
+	t.Run("LargeFileCopyEncrypted_ToTemp_ToEncrypted", func(t *testing.T) {
+		// Test with large file (1MB) to exercise chunk-by-chunk copy path
+		// This verifies consistent behavior with SSE-C and SSE-KMS
+		largeTestData := generateTestData(1024 * 1024) // 1MB
+		objectKey := "large-file-test.bin"
+
+		// Step 1: Upload large object to source bucket (will be automatically encrypted)
+		_, err = client.PutObject(ctx, &s3.PutObjectInput{
+			Bucket: aws.String(srcBucket),
+			Key:    aws.String(objectKey),
+			Body:   bytes.NewReader(largeTestData),
+		})
+		require.NoError(t, err, "Failed to upload large file to source bucket")
+
+		// Verify source object is encrypted
+		srcHead, err := client.HeadObject(ctx, &s3.HeadObjectInput{
+			Bucket: aws.String(srcBucket),
+			Key:    aws.String(objectKey),
+		})
+		require.NoError(t, err, "Failed to HEAD source object")
+		assert.Equal(t, types.ServerSideEncryptionAes256, srcHead.ServerSideEncryption,
+			"Source object should be SSE-S3 encrypted")
+
+		// Step 2: Copy to temp bucket (unencrypted) - exercises chunk-by-chunk decrypt
+		_, err = client.CopyObject(ctx, &s3.CopyObjectInput{
+			Bucket:     aws.String(tempBucket),
+			Key:        aws.String(objectKey),
+			CopySource: aws.String(fmt.Sprintf("%s/%s", srcBucket, objectKey)),
+		})
+		require.NoError(t, err, "Failed to copy large file to temp bucket")
+
+		// Verify temp object is unencrypted and data is correct
+		tempGet, err := client.GetObject(ctx, &s3.GetObjectInput{
+			Bucket: aws.String(tempBucket),
+			Key:    aws.String(objectKey),
+		})
+		require.NoError(t, err, "Failed to GET temp object")
+		tempData, err := io.ReadAll(tempGet.Body)
+		tempGet.Body.Close()
+		require.NoError(t, err, "Failed to read temp object")
+		assertDataEqual(t, largeTestData, tempData, "Temp object data mismatch after decrypt")
+
+		// Step 3: Copy from temp bucket to dest bucket (with default encryption)
+		// This exercises chunk-by-chunk encrypt copy
+		_, err = client.CopyObject(ctx, &s3.CopyObjectInput{
+			Bucket:     aws.String(dstBucket),
+			Key:        aws.String(objectKey),
+			CopySource: aws.String(fmt.Sprintf("%s/%s", tempBucket, objectKey)),
+		})
+		require.NoError(t, err, "Failed to copy large file to destination bucket")
+
+		// Verify destination object is encrypted
+		dstHead, err := client.HeadObject(ctx, &s3.HeadObjectInput{
+			Bucket: aws.String(dstBucket),
+			Key:    aws.String(objectKey),
+		})
+		require.NoError(t, err, "Failed to HEAD destination object")
+		assert.Equal(t, types.ServerSideEncryptionAes256, dstHead.ServerSideEncryption,
+			"Destination object should be SSE-S3 encrypted via bucket default")
+
+		// Verify destination object content is correct after re-encryption
+		dstGet, err := client.GetObject(ctx, &s3.GetObjectInput{
+			Bucket: aws.String(dstBucket),
+			Key:    aws.String(objectKey),
+		})
+		require.NoError(t, err, "Failed to GET destination object")
+		dstData, err := io.ReadAll(dstGet.Body)
+		dstGet.Body.Close()
+		require.NoError(t, err, "Failed to read destination object")
+		assertDataEqual(t, largeTestData, dstData, "Large file data mismatch after re-encryption")
+	})
 }
 
 // REGRESSION TESTS FOR CRITICAL BUGS FIXED
diff --git a/weed/s3api/s3api_object_handlers_copy.go b/weed/s3api/s3api_object_handlers_copy.go
index 0c465d3db..09d009372 100644
--- a/weed/s3api/s3api_object_handlers_copy.go
+++ b/weed/s3api/s3api_object_handlers_copy.go
@@ -199,7 +199,9 @@ func (s3a *S3ApiServer) CopyObjectHandler(w http.ResponseWriter, r *http.Request
 	}
 
 	// Process metadata and tags and apply to destination
-	processedMetadata, tagErr := processMetadataBytes(r.Header, entry.Extended, replaceMeta, replaceTagging)
+	// Use dstEntry.Extended (already filtered) as the source, not entry.Extended,
+	// to preserve the encryption header filtering. Fixes GitHub #7562.
+	processedMetadata, tagErr := processMetadataBytes(r.Header, dstEntry.Extended, replaceMeta, replaceTagging)
 	if tagErr != nil {
 		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
 		return
@@ -1522,7 +1524,7 @@ func (s3a *S3ApiServer) copyMultipartSSECChunk(chunk *filer_pb.FileChunk, copySo
 }
 
 // copyMultipartCrossEncryption handles all cross-encryption and decrypt-only copy scenarios
-// This unified function supports: SSE-C↔SSE-KMS, SSE-C→Plain, SSE-KMS→Plain
+// This unified function supports: SSE-C↔SSE-KMS↔SSE-S3, and any→Plain
 func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *http.Request, state *EncryptionState, dstBucket, dstPath string) ([]*filer_pb.FileChunk, map[string][]byte, error) {
 	var dstChunks []*filer_pb.FileChunk
 
@@ -1531,6 +1533,7 @@ func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *h
 	var destKMSKeyID string
 	var destKMSEncryptionContext map[string]string
 	var destKMSBucketKeyEnabled bool
+	var destSSES3Key *SSES3Key
 
 	if state.DstSSEC {
 		var err error
@@ -1544,7 +1547,13 @@ func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *h
 		if err != nil {
 			return nil, nil, fmt.Errorf("failed to parse destination SSE-KMS headers: %w", err)
 		}
-	} else {
+	} else if state.DstSSES3 {
+		// Generate SSE-S3 key for destination
+		var err error
+		destSSES3Key, err = GenerateSSES3Key()
+		if err != nil {
+			return nil, nil, fmt.Errorf("failed to generate SSE-S3 key: %w", err)
+		}
 	}
 
 	// Parse source encryption parameters
@@ -1563,12 +1572,18 @@ func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *h
 		var err error
 
 		if chunk.GetSseType() == filer_pb.SSEType_SSE_C {
-			copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, sourceSSECKey, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, dstPath, dstBucket, state)
+			copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, sourceSSECKey, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, destSSES3Key, dstPath, dstBucket, state)
 		} else if chunk.GetSseType() == filer_pb.SSEType_SSE_KMS {
-			copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, nil, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, dstPath, dstBucket, state)
+			copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, nil, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, destSSES3Key, dstPath, dstBucket, state)
+		} else if chunk.GetSseType() == filer_pb.SSEType_SSE_S3 {
+			copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, nil, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, destSSES3Key, dstPath, dstBucket, state)
 		} else {
-			// Unencrypted chunk, copy directly
-			copiedChunk, err = s3a.copySingleChunk(chunk, dstPath)
+			// Unencrypted chunk - may need encryption if destination requires it
+			if state.DstSSEC || state.DstSSEKMS || state.DstSSES3 {
+				copiedChunk, err = s3a.copyCrossEncryptionChunk(chunk, nil, destSSECKey, destKMSKeyID, destKMSEncryptionContext, destKMSBucketKeyEnabled, destSSES3Key, dstPath, dstBucket, state)
+			} else {
+				copiedChunk, err = s3a.copySingleChunk(chunk, dstPath)
+			}
 		}
 
 		if err != nil {
@@ -1619,6 +1634,40 @@ func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *h
 		} else {
 			glog.Errorf("Failed to serialize SSE-KMS metadata: %v", serErr)
 		}
+	} else if state.DstSSES3 && destSSES3Key != nil {
+		// For SSE-S3 destination, create object-level metadata
+		var sses3Metadata *SSES3Key
+		if len(dstChunks) == 0 {
+			// Handle 0-byte files - generate IV for metadata even though there's no content to encrypt
+			if entry.Attributes.FileSize != 0 {
+				return nil, nil, fmt.Errorf("internal error: no chunks created for non-empty SSE-S3 destination object")
+			}
+			// Generate IV for 0-byte object metadata
+			iv := make([]byte, s3_constants.AESBlockSize)
+			if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+				return nil, nil, fmt.Errorf("generate IV for 0-byte object: %w", err)
+			}
+			destSSES3Key.IV = iv
+			sses3Metadata = destSSES3Key
+		} else {
+			// For non-empty objects, use the first chunk's metadata
+			if dstChunks[0].GetSseType() != filer_pb.SSEType_SSE_S3 || len(dstChunks[0].GetSseMetadata()) == 0 {
+				return nil, nil, fmt.Errorf("internal error: first chunk is missing expected SSE-S3 metadata for destination object")
+			}
+			keyManager := GetSSES3KeyManager()
+			var err error
+			sses3Metadata, err = DeserializeSSES3Metadata(dstChunks[0].GetSseMetadata(), keyManager)
+			if err != nil {
+				return nil, nil, fmt.Errorf("failed to deserialize SSE-S3 metadata from first chunk: %w", err)
+			}
+		}
+		// Use the derived key with its IV for object-level metadata
+		keyData, serErr := SerializeSSES3Metadata(sses3Metadata)
+		if serErr != nil {
+			return nil, nil, fmt.Errorf("failed to serialize SSE-S3 metadata: %w", serErr)
+		}
+		dstMetadata[s3_constants.SeaweedFSSSES3Key] = keyData
+		dstMetadata[s3_constants.AmzServerSideEncryption] = []byte("AES256")
 	}
 	// For unencrypted destination, no metadata needed (dstMetadata remains empty)
 
@@ -1626,7 +1675,7 @@ func (s3a *S3ApiServer) copyMultipartCrossEncryption(entry *filer_pb.Entry, r *h
 }
 
 // copyCrossEncryptionChunk handles copying a single chunk with cross-encryption support
-func (s3a *S3ApiServer) copyCrossEncryptionChunk(chunk *filer_pb.FileChunk, sourceSSECKey *SSECustomerKey, destSSECKey *SSECustomerKey, destKMSKeyID string, destKMSEncryptionContext map[string]string, destKMSBucketKeyEnabled bool, dstPath, dstBucket string, state *EncryptionState) (*filer_pb.FileChunk, error) {
+func (s3a *S3ApiServer) copyCrossEncryptionChunk(chunk *filer_pb.FileChunk, sourceSSECKey *SSECustomerKey, destSSECKey *SSECustomerKey, destKMSKeyID string, destKMSEncryptionContext map[string]string, destKMSBucketKeyEnabled bool, destSSES3Key *SSES3Key, dstPath, dstBucket string, state *EncryptionState) (*filer_pb.FileChunk, error) {
 	// Create destination chunk
 	dstChunk := s3a.createDestinationChunk(chunk, chunk.Offset, chunk.Size)
 
@@ -1726,6 +1775,30 @@ func (s3a *S3ApiServer) copyCrossEncryptionChunk(chunk *filer_pb.FileChunk, sour
 			previewLen = len(finalData)
 		}
 
+	} else if chunk.GetSseType() == filer_pb.SSEType_SSE_S3 {
+		// Decrypt SSE-S3 source
+		if len(chunk.GetSseMetadata()) == 0 {
+			return nil, fmt.Errorf("SSE-S3 chunk missing per-chunk metadata")
+		}
+
+		keyManager := GetSSES3KeyManager()
+		sourceSSEKey, err := DeserializeSSES3Metadata(chunk.GetSseMetadata(), keyManager)
+		if err != nil {
+			return nil, fmt.Errorf("failed to deserialize SSE-S3 metadata: %w", err)
+		}
+
+		decryptedReader, decErr := CreateSSES3DecryptedReader(bytes.NewReader(encryptedData), sourceSSEKey, sourceSSEKey.IV)
+		if decErr != nil {
+			return nil, fmt.Errorf("create SSE-S3 decrypted reader: %w", decErr)
+		}
+
+		decryptedData, readErr := io.ReadAll(decryptedReader)
+		if readErr != nil {
+			return nil, fmt.Errorf("decrypt SSE-S3 chunk data: %w", readErr)
+		}
+		finalData = decryptedData
+		glog.V(4).Infof("Decrypted SSE-S3 chunk, size: %d", len(finalData))
+
 	} else {
 		// Source is unencrypted
 		finalData = encryptedData
@@ -1787,6 +1860,36 @@ func (s3a *S3ApiServer) copyCrossEncryptionChunk(chunk *filer_pb.FileChunk, sour
 		dstChunk.SseMetadata = kmsMetadata
 
 		glog.V(4).Infof("Re-encrypted chunk with SSE-KMS")
+
+	} else if state.DstSSES3 && destSSES3Key != nil {
+		// Encrypt with SSE-S3
+		encryptedReader, iv, encErr := CreateSSES3EncryptedReader(bytes.NewReader(finalData), destSSES3Key)
+		if encErr != nil {
+			return nil, fmt.Errorf("create SSE-S3 encrypted reader: %w", encErr)
+		}
+
+		reencryptedData, readErr := io.ReadAll(encryptedReader)
+		if readErr != nil {
+			return nil, fmt.Errorf("re-encrypt with SSE-S3: %w", readErr)
+		}
+		finalData = reencryptedData
+
+		// Create per-chunk SSE-S3 metadata with chunk-specific IV
+		chunkSSEKey := &SSES3Key{
+			Key:       destSSES3Key.Key,
+			KeyID:     destSSES3Key.KeyID,
+			Algorithm: destSSES3Key.Algorithm,
+			IV:        iv,
+		}
+		sses3Metadata, err := SerializeSSES3Metadata(chunkSSEKey)
+		if err != nil {
+			return nil, fmt.Errorf("serialize SSE-S3 metadata: %w", err)
+		}
+
+		dstChunk.SseType = filer_pb.SSEType_SSE_S3
+		dstChunk.SseMetadata = sses3Metadata
+
+		glog.V(4).Infof("Re-encrypted chunk with SSE-S3")
 	}
 	// For unencrypted destination, finalData remains as decrypted plaintext
 
diff --git a/weed/s3api/s3api_object_handlers_copy_unified.go b/weed/s3api/s3api_object_handlers_copy_unified.go
index 255c3eb2d..f1b4ff280 100644
--- a/weed/s3api/s3api_object_handlers_copy_unified.go
+++ b/weed/s3api/s3api_object_handlers_copy_unified.go
@@ -1,7 +1,6 @@
 package s3api
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"net/http"
@@ -133,9 +132,9 @@ func (s3a *S3ApiServer) executeEncryptCopy(entry *filer_pb.Entry, r *http.Reques
 	}
 
 	if state.DstSSES3 {
-		// Use streaming copy for SSE-S3 encryption
-		chunks, err := s3a.executeStreamingReencryptCopy(entry, r, state, dstPath)
-		return chunks, nil, err
+		// Use chunk-by-chunk copy for SSE-S3 encryption (consistent with SSE-C and SSE-KMS)
+		glog.V(2).Infof("Plain→SSE-S3 copy: using unified multipart encrypt copy")
+		return s3a.copyMultipartCrossEncryption(entry, r, state, dstBucket, dstPath)
 	}
 
 	return nil, nil, fmt.Errorf("unknown target encryption type")
@@ -143,30 +142,18 @@ func (s3a *S3ApiServer) executeEncryptCopy(entry *filer_pb.Entry, r *http.Reques
 
 // executeDecryptCopy handles encrypted → plain copies
 func (s3a *S3ApiServer) executeDecryptCopy(entry *filer_pb.Entry, r *http.Request, state *EncryptionState, dstPath string) ([]*filer_pb.FileChunk, map[string][]byte, error) {
-	// Use unified multipart-aware decrypt copy for all encryption types
-	if state.SrcSSEC || state.SrcSSEKMS {
+	// Use unified multipart-aware decrypt copy for all encryption types (consistent chunk-by-chunk)
+	if state.SrcSSEC || state.SrcSSEKMS || state.SrcSSES3 {
 		glog.V(2).Infof("Encrypted→Plain copy: using unified multipart decrypt copy")
 		return s3a.copyMultipartCrossEncryption(entry, r, state, "", dstPath)
 	}
 
-	if state.SrcSSES3 {
-		// Use streaming copy for SSE-S3 decryption
-		chunks, err := s3a.executeStreamingReencryptCopy(entry, r, state, dstPath)
-		return chunks, nil, err
-	}
-
 	return nil, nil, fmt.Errorf("unknown source encryption type")
 }
 
 // executeReencryptCopy handles encrypted → encrypted copies with different keys/methods
 func (s3a *S3ApiServer) executeReencryptCopy(entry *filer_pb.Entry, r *http.Request, state *EncryptionState, dstBucket, dstPath string) ([]*filer_pb.FileChunk, map[string][]byte, error) {
-	// Check if we should use streaming copy for better performance
-	if s3a.shouldUseStreamingCopy(entry, state) {
-		chunks, err := s3a.executeStreamingReencryptCopy(entry, r, state, dstPath)
-		return chunks, nil, err
-	}
-
-	// Fallback to chunk-by-chunk approach for compatibility
+	// Use chunk-by-chunk approach for all cross-encryption scenarios (consistent behavior)
 	if state.SrcSSEC && state.DstSSEC {
 		return s3a.copyChunksWithSSEC(entry, r)
 	}
@@ -177,83 +164,8 @@ func (s3a *S3ApiServer) executeReencryptCopy(entry *filer_pb.Entry, r *http.Requ
 		return chunks, dstMetadata, err
 	}
 
-	if state.SrcSSEC && state.DstSSEKMS {
-		// SSE-C → SSE-KMS: use unified multipart-aware cross-encryption copy
-		glog.V(2).Infof("SSE-C→SSE-KMS cross-encryption copy: using unified multipart copy")
-		return s3a.copyMultipartCrossEncryption(entry, r, state, dstBucket, dstPath)
-	}
-
-	if state.SrcSSEKMS && state.DstSSEC {
-		// SSE-KMS → SSE-C: use unified multipart-aware cross-encryption copy
-		glog.V(2).Infof("SSE-KMS→SSE-C cross-encryption copy: using unified multipart copy")
-		return s3a.copyMultipartCrossEncryption(entry, r, state, dstBucket, dstPath)
-	}
-
-	// Handle SSE-S3 cross-encryption scenarios
-	if state.SrcSSES3 || state.DstSSES3 {
-		// Any scenario involving SSE-S3 uses streaming copy
-		chunks, err := s3a.executeStreamingReencryptCopy(entry, r, state, dstPath)
-		return chunks, nil, err
-	}
-
-	return nil, nil, fmt.Errorf("unsupported cross-encryption scenario")
-}
-
-// shouldUseStreamingCopy determines if streaming copy should be used
-func (s3a *S3ApiServer) shouldUseStreamingCopy(entry *filer_pb.Entry, state *EncryptionState) bool {
-	// Use streaming copy for large files or when beneficial
-	fileSize := entry.Attributes.FileSize
-
-	// Use streaming for files larger than 10MB
-	if fileSize > 10*1024*1024 {
-		return true
-	}
-
-	// Check if this is a multipart encrypted object
-	isMultipartEncrypted := false
-	if state.IsSourceEncrypted() {
-		encryptedChunks := 0
-		for _, chunk := range entry.GetChunks() {
-			if chunk.GetSseType() != filer_pb.SSEType_NONE {
-				encryptedChunks++
-			}
-		}
-		isMultipartEncrypted = encryptedChunks > 1
-	}
-
-	// For multipart encrypted objects, avoid streaming copy to use per-chunk metadata approach
-	if isMultipartEncrypted {
-		glog.V(3).Infof("Multipart encrypted object detected, using chunk-by-chunk approach")
-		return false
-	}
-
-	// Use streaming for cross-encryption scenarios (for single-part objects only)
-	if state.IsSourceEncrypted() && state.IsTargetEncrypted() {
-		srcType := s3a.getEncryptionTypeString(state.SrcSSEC, state.SrcSSEKMS, state.SrcSSES3)
-		dstType := s3a.getEncryptionTypeString(state.DstSSEC, state.DstSSEKMS, state.DstSSES3)
-		if srcType != dstType {
-			return true
-		}
-	}
-
-	// Use streaming for compressed files
-	if isCompressedEntry(entry) {
-		return true
-	}
-
-	// Use streaming for SSE-S3 scenarios (always)
-	if state.SrcSSES3 || state.DstSSES3 {
-		return true
-	}
-
-	return false
-}
-
-// executeStreamingReencryptCopy performs streaming re-encryption copy
-func (s3a *S3ApiServer) executeStreamingReencryptCopy(entry *filer_pb.Entry, r *http.Request, state *EncryptionState, dstPath string) ([]*filer_pb.FileChunk, error) {
-	// Create streaming copy manager
-	streamingManager := NewStreamingCopyManager(s3a)
-
-	// Execute streaming copy
-	return streamingManager.ExecuteStreamingCopy(context.Background(), entry, r, dstPath, state)
+	// All other cross-encryption scenarios use unified multipart copy
+	// This includes: SSE-C↔SSE-KMS, SSE-C↔SSE-S3, SSE-KMS↔SSE-S3, SSE-S3↔SSE-S3
+	glog.V(2).Infof("Cross-encryption copy: using unified multipart copy")
+	return s3a.copyMultipartCrossEncryption(entry, r, state, dstBucket, dstPath)
 }
diff --git a/weed/s3api/s3api_streaming_copy.go b/weed/s3api/s3api_streaming_copy.go
index 457986858..94729c003 100644
--- a/weed/s3api/s3api_streaming_copy.go
+++ b/weed/s3api/s3api_streaming_copy.go
@@ -59,18 +59,19 @@ func NewStreamingCopyManager(s3a *S3ApiServer) *StreamingCopyManager {
 	}
 }
 
-// ExecuteStreamingCopy performs a streaming copy operation
-func (scm *StreamingCopyManager) ExecuteStreamingCopy(ctx context.Context, entry *filer_pb.Entry, r *http.Request, dstPath string, state *EncryptionState) ([]*filer_pb.FileChunk, error) {
+// ExecuteStreamingCopy performs a streaming copy operation and returns the encryption spec
+// The encryption spec is needed for SSE-S3 to properly set destination metadata (fixes GitHub #7562)
+func (scm *StreamingCopyManager) ExecuteStreamingCopy(ctx context.Context, entry *filer_pb.Entry, r *http.Request, dstPath string, state *EncryptionState) ([]*filer_pb.FileChunk, *EncryptionSpec, error) {
 	// Create streaming copy specification
 	spec, err := scm.createStreamingSpec(entry, r, state)
 	if err != nil {
-		return nil, fmt.Errorf("create streaming spec: %w", err)
+		return nil, nil, fmt.Errorf("create streaming spec: %w", err)
 	}
 
 	// Create source reader from entry
 	sourceReader, err := scm.createSourceReader(entry)
 	if err != nil {
-		return nil, fmt.Errorf("create source reader: %w", err)
+		return nil, nil, fmt.Errorf("create source reader: %w", err)
 	}
 	defer sourceReader.Close()
 
@@ -79,11 +80,16 @@ func (scm *StreamingCopyManager) ExecuteStreamingCopy(ctx context.Context, entry
 	// Create processing pipeline
 	processedReader, err := scm.createProcessingPipeline(spec)
 	if err != nil {
-		return nil, fmt.Errorf("create processing pipeline: %w", err)
+		return nil, nil, fmt.Errorf("create processing pipeline: %w", err)
 	}
 
 	// Stream to destination
-	return scm.streamToDestination(ctx, processedReader, spec, dstPath)
+	chunks, err := scm.streamToDestination(ctx, processedReader, spec, dstPath)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return chunks, spec.EncryptionSpec, nil
 }
 
 // createStreamingSpec creates a streaming specification based on copy parameters
@@ -453,8 +459,8 @@ func (scm *StreamingCopyManager) streamToChunks(ctx context.Context, reader io.R
 	for {
 		n, err := reader.Read(buffer)
 		if n > 0 {
-			// Create chunk for this data
-			chunk, chunkErr := scm.createChunkFromData(buffer[:n], offset, dstPath)
+		// Create chunk for this data, setting SSE type and per-chunk metadata (including chunk-specific IVs for SSE-S3)
+		chunk, chunkErr := scm.createChunkFromData(buffer[:n], offset, dstPath, spec.EncryptionSpec)
 			if chunkErr != nil {
 				return nil, fmt.Errorf("create chunk from data: %w", chunkErr)
 			}
@@ -474,7 +480,7 @@ func (scm *StreamingCopyManager) streamToChunks(ctx context.Context, reader io.R
 }
 
 // createChunkFromData creates a chunk from streaming data
-func (scm *StreamingCopyManager) createChunkFromData(data []byte, offset int64, dstPath string) (*filer_pb.FileChunk, error) {
+func (scm *StreamingCopyManager) createChunkFromData(data []byte, offset int64, dstPath string, encSpec *EncryptionSpec) (*filer_pb.FileChunk, error) {
 	// Assign new volume
 	assignResult, err := scm.s3a.assignNewVolume(dstPath)
 	if err != nil {
@@ -487,6 +493,42 @@ func (scm *StreamingCopyManager) createChunkFromData(data []byte, offset int64,
 		Size:   uint64(len(data)),
 	}
 
+	// Set SSE type and metadata on chunk if destination is encrypted
+	// This is critical for GetObject to know to decrypt the data - fixes GitHub #7562
+	if encSpec != nil && encSpec.NeedsEncryption {
+		switch encSpec.DestinationType {
+		case EncryptionTypeSSEC:
+			chunk.SseType = filer_pb.SSEType_SSE_C
+			// SSE-C metadata is handled at object level, not per-chunk for streaming copy
+		case EncryptionTypeSSEKMS:
+			chunk.SseType = filer_pb.SSEType_SSE_KMS
+			// SSE-KMS metadata is handled at object level, not per-chunk for streaming copy
+		case EncryptionTypeSSES3:
+			chunk.SseType = filer_pb.SSEType_SSE_S3
+			// Create per-chunk SSE-S3 metadata with chunk-specific IV
+			if sseKey, ok := encSpec.DestinationKey.(*SSES3Key); ok {
+				// Calculate chunk-specific IV using base IV and chunk offset
+				baseIV := encSpec.DestinationIV
+				if len(baseIV) == 0 {
+					return nil, fmt.Errorf("SSE-S3 encryption requires DestinationIV to be set for chunk at offset %d", offset)
+				}
+				chunkIV, _ := calculateIVWithOffset(baseIV, offset)
+				// Create chunk key with the chunk-specific IV
+				chunkSSEKey := &SSES3Key{
+					Key:       sseKey.Key,
+					KeyID:     sseKey.KeyID,
+					Algorithm: sseKey.Algorithm,
+					IV:        chunkIV,
+				}
+				chunkMetadata, serErr := SerializeSSES3Metadata(chunkSSEKey)
+				if serErr != nil {
+					return nil, fmt.Errorf("failed to serialize chunk SSE-S3 metadata: %w", serErr)
+				}
+				chunk.SseMetadata = chunkMetadata
+			}
+		}
+	}
+
 	// Set file ID
 	if err := scm.s3a.setChunkFileId(chunk, assignResult); err != nil {
 		return nil, err