diff --git a/weed/s3api/s3api_object_handlers_copy.go b/weed/s3api/s3api_object_handlers_copy.go
index e688ade2a..abb1b7bd5 100644
--- a/weed/s3api/s3api_object_handlers_copy.go
+++ b/weed/s3api/s3api_object_handlers_copy.go
@@ -155,6 +155,20 @@ func (s3a *S3ApiServer) CopyObjectHandler(w http.ResponseWriter, r *http.Request
 		return
 	}
 
+	// Determine whether we can reuse the source MD5 (direct copy without encryption changes).
+	canReuseSourceMd5 := false
+	var sourceMd5 []byte
+	if entry.Attributes != nil && len(entry.Attributes.Md5) > 0 {
+		sourceMd5 = append([]byte(nil), entry.Attributes.Md5...)
+		srcPath := fmt.Sprintf("%s/%s/%s", s3a.option.BucketsPath, srcBucket, srcObject)
+		dstPath := fmt.Sprintf("%s/%s/%s", s3a.option.BucketsPath, dstBucket, dstObject)
+		state := DetectEncryptionStateWithEntry(entry, r, srcPath, dstPath)
+		s3a.applyCopyBucketDefaultEncryption(state, dstBucket)
+		if strategy, err := DetermineUnifiedCopyStrategy(state, entry.Extended, r); err == nil && strategy == CopyStrategyDirect {
+			canReuseSourceMd5 = true
+		}
+	}
+
 	// Create new entry for destination
 	dstEntry := &filer_pb.Entry{
 		Attributes: &filer_pb.FuseAttributes{
@@ -237,9 +251,17 @@ func (s3a *S3ApiServer) CopyObjectHandler(w http.ResponseWriter, r *http.Request
 				}
 			}
 		}
+
+		if dstEntry.Attributes != nil {
+			if len(dstEntry.Attributes.Md5) == 0 && canReuseSourceMd5 {
+				dstEntry.Attributes.Md5 = append([]byte(nil), sourceMd5...)
+			} else if uint64(len(dstEntry.Content)) == dstEntry.Attributes.FileSize {
+				dstEntry.Attributes.Md5 = util.Md5(dstEntry.Content)
+			}
+		}
 	} else {
 		// Use unified copy strategy approach
-		dstChunks, dstMetadata, copyErr := s3a.executeUnifiedCopyStrategy(entry, r, dstBucket, srcObject, dstObject)
+		dstChunks, dstMetadata, copyErr := s3a.executeUnifiedCopyStrategy(entry, r, srcBucket, dstBucket, srcObject, dstObject)
 		if copyErr != nil {
 			glog.Errorf("CopyObjectHandler unified copy error: %v", copyErr)
 			// Map errors to appropriate S3 errors
@@ -257,6 +279,10 @@ func (s3a *S3ApiServer) CopyObjectHandler(w http.ResponseWriter, r *http.Request
 			}
 			glog.V(2).Infof("Applied %d destination metadata entries for copy: %s", len(dstMetadata), r.URL.Path)
 		}
+
+		if dstEntry.Attributes != nil && len(dstEntry.Attributes.Md5) == 0 && canReuseSourceMd5 {
+			dstEntry.Attributes.Md5 = append([]byte(nil), sourceMd5...)
+		}
 	}
 
 	// Check if destination bucket has versioning enabled
diff --git a/weed/s3api/s3api_object_handlers_copy_unified.go b/weed/s3api/s3api_object_handlers_copy_unified.go
index 265e7cf54..0efda0de6 100644
--- a/weed/s3api/s3api_object_handlers_copy_unified.go
+++ b/weed/s3api/s3api_object_handlers_copy_unified.go
@@ -13,26 +13,16 @@ import (
 
 // executeUnifiedCopyStrategy executes the appropriate copy strategy based on encryption state
 // Returns chunks and destination metadata that should be applied to the destination entry
-func (s3a *S3ApiServer) executeUnifiedCopyStrategy(entry *filer_pb.Entry, r *http.Request, dstBucket, srcObject, dstObject string) ([]*filer_pb.FileChunk, map[string][]byte, error) {
+func (s3a *S3ApiServer) executeUnifiedCopyStrategy(entry *filer_pb.Entry, r *http.Request, srcBucket, dstBucket, srcObject, dstObject string) ([]*filer_pb.FileChunk, map[string][]byte, error) {
 	// Detect encryption state (using entry-aware detection for multipart objects)
-	srcPath := fmt.Sprintf("%s/%s/%s", s3a.option.BucketsPath, r.Header.Get("X-Amz-Copy-Source-Bucket"), srcObject)
+	srcPath := fmt.Sprintf("%s/%s/%s", s3a.option.BucketsPath, srcBucket, srcObject)
 	dstPath := fmt.Sprintf("%s/%s/%s", s3a.option.BucketsPath, dstBucket, dstObject)
 	state := DetectEncryptionStateWithEntry(entry, r, srcPath, dstPath)
 
 	// Debug logging for encryption state
 
 	// Apply bucket default encryption if no explicit encryption specified
-	if !state.IsTargetEncrypted() {
-		bucketMetadata, err := s3a.getBucketMetadata(dstBucket)
-		if err == nil && bucketMetadata != nil && bucketMetadata.Encryption != nil {
-			switch bucketMetadata.Encryption.SseAlgorithm {
-			case "aws:kms":
-				state.DstSSEKMS = true
-			case "AES256":
-				state.DstSSES3 = true
-			}
-		}
-	}
+	s3a.applyCopyBucketDefaultEncryption(state, dstBucket)
 
 	// Determine copy strategy
 	strategy, err := DetermineUnifiedCopyStrategy(state, entry.Extended, r)
@@ -169,3 +159,18 @@ func (s3a *S3ApiServer) executeReencryptCopy(entry *filer_pb.Entry, r *http.Requ
 	glog.V(2).Infof("Cross-encryption copy: using unified multipart copy")
 	return s3a.copyMultipartCrossEncryption(entry, r, state, dstBucket, dstPath)
 }
+
+// applyCopyBucketDefaultEncryption applies the destination bucket's default encryption settings if no explicit encryption is specified
+func (s3a *S3ApiServer) applyCopyBucketDefaultEncryption(state *EncryptionState, dstBucket string) {
+	if !state.IsTargetEncrypted() {
+		bucketMetadata, err := s3a.getBucketMetadata(dstBucket)
+		if err == nil && bucketMetadata != nil && bucketMetadata.Encryption != nil {
+			switch bucketMetadata.Encryption.SseAlgorithm {
+			case "aws:kms":
+				state.DstSSEKMS = true
+			case "AES256":
+				state.DstSSES3 = true
+			}
+		}
+	}
+}