Add multipart support in SSE-C encryption (#5576)

*) Add Put/Get support of multipart in encryption
*) Add GET Range support for encryption
*) Add CopyPart encrypted support
*) Support decrypting of large single PUT object

cmd/object-api-datatypes.go

@@ -101,6 +101,9 @@ type ObjectInfo struct {
 	// User-Defined metadata
 	UserDefined map[string]string
 
+	// List of individual parts, maximum size of upto 10,000
+	Parts []objectPartInfo `json:"-"`
+
 	// Implements writer and reader used by CopyObject API
 	Writer       io.WriteCloser `json:"-"`
 	Reader       *hash.Reader   `json:"-"`
@@ -138,6 +141,9 @@ type ListPartsInfo struct {
 	// List of all parts.
 	Parts []PartInfo
 
+	// Any metadata set during InitMultipartUpload, including encryption headers.
+	UserDefined map[string]string
+
 	EncodingType string // Not supported yet.
 }