Ethernet Security Relies on Efficient Media Access Control Security (MACsec)

Introduction

There is an ever-increasing demand for bandwidth, driven by an exponential growth in the number of devices connected to the cloud and a broadening variety of sensors, applications, and services, resulting in an explosion of data traffic. This in turn, drives the proliferation of high bandwidth interfaces such as Ethernet, PCIe/CXL, and DDR to sustain faster data movement and increased processing and storage capacities. End-to-end data security in the connected ecosystem is more critical than ever, including when data is at rest and when it is in motion, both as it is communicated between devices and the cloud and while it is processed or stored to a device. 

Ethernet-connected devices, like computers, servers, hubs, routers, and more, are expanding in every direction, including high performance computing, 5G, mobile and automotive markets, all requiring security. Security on the internet or any other ethernet network depends on encryption. The more encryption is used, the harder it is for attackers to steal data, eavesdrop on communications, and/or compromise systems. 

Security on the internet or any other Ethernet network depends on encryption, for the privacy of communication and integrity and authentication using shared authenticated keys. There are several different ways to encrypt ethernet traffic, and they occur at different layers in the OSI stack on which it is based:  

• TLS, developed in 1999 as an enhancement of SSL, is implemented at the transport layer of TCP/IP (OSI layer 4).  DTLS initially proposed in April of 2006 via RFC 4347 applies to datagram protocols such as UDP/IP (also layer 4). As such, it is not restricted to Ethernet but can only secure a single stream or one communication channel at a time. TLS protects web browsers, client applications, and all the applications’ communications to cloud services. HTTPS and SSH are examples of protocols that can leverage TLS – and the implementation is entirely within the control of the software.  
• IPsec: If encryption is needed to protect networks (as well as anything else traversing the IP protocol), IPsec is an option, implemented at the network layer of the OSI stack (layer 3), often as a VPN connection. IPsec is usually implemented as a software stack and used voluntarily by users. 
  
• MACsec: when the encryption on an Ethernet network is required for all traffic, regardless of the upper layer protocols involved, it is necessary to enforce it at the hardware level (link or medium access layer 2). Fortunately, this is precisely what MACsec (aka IEEE 802.1AE) provides. MACsec is used to protect network-to-network or device-to-network connections. Each connection on an Ethernet network (host to host, host to switch, or switch to switch) will traverse both encrypted and unencrypted traffic if control over that encryption is imposed at higher layers but once MACsec is enabled for a link, all traffic on that connection will be secured from prying eyes. As with its upper-layer cousins, MACsec provides both encryption and authentication services by adding two additional fields to the ethernet frame:
  
  • Security Tag, which is an extension of the EtherType field also used for VLAN tagging
  • Message Authentication Code (ICV) to define the integrity check value algorithm

Setting up a MACsec encrypted connection involves five steps:

• Step 1: Mutual peer authentication is established using a Pre-shared Key (PSK).
• Step 2: After successful authentication, a secure Connectivity Association Key Name (CKN) is exchanged to form a connectivity association between the peers. The MKA ICV is validated with a Connectivity Association Key (CAK), which is effectively a secret key.
• Step 3: The priority value of the two endpoints is used to elect which becomes the key server while the other device functions as a key client. 
• Step 4: The key server then generates and distributes the Secure Association Key (SAK) to the key client (peer) to form a security association.
• Step 5: Encrypted data can now be exchanged between peers.

MACsec hardware encryption also provides the lowest latency security as compared to options implemented at higher layers of the OSI stack.

With the Synopsys MACsec Security Modules, designers can take advantage of:

• Compliance with the IEEE 802.1AE standard
• Per frame security processing, including encapsulation/decapsulation and frame validation
• Scalable throughput to 100+ Gbps based on pipelined AES-GCM cryptography with optimized latency
• Modes
  • Encryption/decryption and authentication
  • Authentication only
• 128-bit & 256-bit key sizes
• Fixed Ingress/Egress latency
• Extended packet numbering as per IEEE 802.1AEbn standard
• Jumbo frames support
• SecTag insertion & removal
• Configurable number of Secure Channels and Associations
• Configurable replay protection window size
• Configurable offset
• Programmable confidentiality offset
• VLAN tag in the clear support
• Selectable bypass mode