Synology DSM 7.2 introduced a highly anticipated feature: volume-level encryption. This data protection mechanism works faster and has less limitations than shared folder encryption, which was the only encryption option supported in prior DSM releases. However, upon investigation, we determined that the implementation of the encryption key management mechanism for full-volume encryption fails to meet the expected standards of security for encrypted data for many users.

Many Linux distributions including those used in off the shelf Network Attached Storage (NAS) devices have the ability to protect users’ data with one or more types of encryption. Full-disk and folder-based encryption options are commonly available, each with its own set of pros and contras. The new native ZFS encryption made available in OpenZFS 2.0 is designed to combine the benefits of full-disk and folder-based encryption without the associated drawbacks. In this article, we’ll compare the strengths and weaknesses of LUKS, eCryptFS and ZFS encryption.

Established NAS manufacturers often offer some kind of encryption to their users. While anyone can use “military-grade AES-256 encryption”, the implementation details vary greatly. Synology, Asustor, and TerraMaster implement folder-based encryption, while QNAP, Thecus, and Asustor (MyAcrhive) employ full-disk encryption; the full comparison is available here. In this article, we’ll have a look at encryption methods used in TrueNAS, a system commonly used by computer enthusiasts for building custom NAS servers.

More than a year ago, we started researching the available encryption options in off the shelf network attached storage devices. We started with Synology devices, followed by Asustor, TerraMaster, Thecus, and finally Qnap. The manufacturers exhibit vastly different approaches to data protection, with different limitations, security implications and vulnerabilities. Today we are publishing the aggregate results of our analysis.

ASUSTOR advertises secure AES encryption with a 256-bit key. According to the manufacturer, AES-256 encryption is made available through the entire range of its current NAS devices. Unlike other manufacturers, ASUSTOR is very upfront regarding the type of encryption employed by its NAS devices: “ASUSTOR NAS offers folder based military grade AES 256-bit encryption”. As a result, we’re once again dealing with folder-based encryption running on top of the open-source encrypting file system eCryptfs. We’ve already seen eCryptfs-based encryption in attached storage devices made by Synology and TerraMaster. Does ASUSTOR have any surprises, or will its implementation of folder-based encryption suffer from the many restrictions and limitations? Let’s find out.

TerraMaster is a relatively new company specializing in network attached storage and direct attached storage solutions. The majority of TerraMaster NAS solutions are ARM64 and Intel-based boxes aimed at the home and SOHO users. TerraMaster’s OS (TOS) is based on Linux. At this time, TOS 4.1 is the current version of the OS.

Thecus has been manufacturing NAS devices for more than 15 years. The company develops an in-house Linux-based NAS OS, the ThecusOS. At this time, the most current version of the OS is ThecusOS 7. Thecus advertises secure data encryption in most of its NAS devices. The company’s volume-based encryption tool allows users to fully encrypt their entire RAID volume, defending essential data in instances of theft of the physical device. We found Thecus’ implementation of encryption somewhat unique. In this research, we’ll verify the manufacturer’s claims and check just how secure is Thecus’ implementation of 256-bit AES encryption.

Home users and small offices are served by two major manufacturers of network attached storage devices (NAS): QNAP and Synology, with Western Digital being a distant third. All Qnap and Synology network attached storage models are advertised with support for hardware-accelerated AES encryption. Encrypted NAS devices can be a real roadblock on the way of forensic investigations. In this article, we’ll review the common encryption scenarios used in home and small office models of network attached storage devices made by Synology. (more…)