ZyXEL P-2802HW-I1 User Guide - Page 198

Chapter 14 VPN Screens Table 77 VPN Setup; Edit LABEL DESCRIPTION Encryption Algorithm Select DES, 3DES, AES or NULL from the drop-down list box. When you use one of these encryption algorithms for data communications, both the sending device and the receiving device must use the same secret key, which can be used to encrypt and decrypt the message or to generate and verify a message authentication code. The DES encryption algorithm uses a 56-bit key. Triple DES (3DES) is a variation on DES that uses a 168-bit key. As a result, 3DES is more secure than DES. It also requires more processing power, resulting in increased latency and decreased throughput. This implementation of AES uses a 128-bit key. AES is faster than 3DES. Select NULL to set up a tunnel without encryption. When you select NULL, you do not enter an encryption key. Authentication Algorithm Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet data. The SHA1 algorithm is generally considered stronger than MD5, but is slower. Select MD5 for minimal security and SHA-1 for maximum security. Advanced Setup Click Advanced to configure more detailed settings of your IKE key management. Back Click Back to return to the previous screen. Apply Click Apply to save your changes back to the ZyXEL Device. Cancel Click Cancel to begin configuring this screen afresh. Advanced Setup Click Advanced Setup to configure more detailed settings of your IKE key management. 14.12 IKE Phases There are two phases to every IKE (Internet Key Exchange) negotiation - phase 1 (Authentication) and phase 2 (Key Exchange). A phase 1 exchange establishes an IKE SA and the second one uses that SA to negotiate SAs for IPSec. Figure 111 Two Phases to Set Up the IPSec SA 198 In phase 1 you must: • Choose a negotiation mode. • Authenticate the connection by entering a pre-shared key. P-2802H(W)(L)-I Series User's Guide