if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	if isEncrypted {
		sseS3 := crypto.S3.IsRequested(r.Header) || crypto.S3.IsEncrypted(mi.UserDefined)
		partInfo.ETag = tryDecryptETag(objectEncryptionKey[:], partInfo.ETag, sseS3)
	}

	response := generateCopyObjectPartResponse(partInfo.ETag, partInfo.LastModified)
	encodedSuccessResponse := encodeResponse(response)

	if err != nil {
		return objInfo.ETag
	}
	return tryDecryptETag(objectEncryptionKey, objInfo.ETag, true)
}

// helper to decrypt Etag given object encryption key and encrypted ETag
func tryDecryptETag(key []byte, encryptedETag string, sses3 bool) string {
	// ETag for SSE-C or SSE-KMS encrypted objects need not be content MD5Sum.While encrypted

			}
			return oi, invp
		}
		expPart := currentFI.Parts[partIdx]

		// ensure that part ETag is canonicalized to strip off extraneous quotes
		part.ETag = canonicalizeETag(part.ETag)
		expETag := tryDecryptETag(objectEncryptionKey, expPart.ETag, kind == crypto.S3)
		if expETag != part.ETag {
			invp := InvalidPart{
				PartNumber: part.PartNumber,
				ExpETag:    expETag,
				GotETag:    part.ETag,
			}