ZyXEL Communications Internet Security Gateway ZyWALL 2 Series User Manual page 519

FIELD
Encryption When DES is used for data communications, both sender and receiver must
Algorithm know the same secret key, which can be used to encrypt and decrypt the
message or to generate and verify a message authentication code. ZyWALL
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 slightly increased latency and decreased throughput.
This implementation of AES uses a 128-bit key. AES is faster than 3DES.
Press [SPACE BAR] to choose from DES, 3DES or AES and then press
[ENTER].
Authentication MD5 (Message Digest 5) and SHA1 (Secure Hash Algorithm) are hash
Algorithm algorithms used to authenticate packet data. The SHA1 algorithm is generally
considered stronger than MD5, but is slightly slower.
Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER].
SA Life Time Define the length of time before an IKE Security Association automatically
(Seconds) renegotiates in this field. It may range from 180 to 3,000,000 seconds (almost
35 days).
A short SA Life Time increases security by forcing the two VPN gateways to
update the encryption and authentication keys. However, every time the VPN
tunnel renegotiates, all users accessing remote resources are temporarily
disconnected.
Key Group You must choose a key group for phase 1 IKE setup. DH1 (default) refers to
Diffie-Hellman Group 1 a 768 bit random number. DH2 refers to Diffie-Hellman
Group 2 a 1024 bit (1Kb) random number.
Phase 2
Active Protocol Press [SPACE BAR] to choose from ESP or AH and then press [ENTER]. See
earlier for a discussion of these protocols.
Encryption Press [SPACE BAR] to choose from NULL, DES, 3DES or AES and then
Algorithm press [ENTER]. Select NULL to set up a tunnel without encryption.
Authentication Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER].
Algorithm
SA Life Time Define the length of time before an IPSec Security Association automatically
(Seconds) renegotiates in this field. It may range from 180 to 3,000,000 seconds (almost
35 days).
VPN/IPSec Setup
Table 37-3
Menu 27.1.1.1: IKE Setup
DESCRIPTION
ZyWALL 2 Series User's Guide
EXAMPLE
DES
SHA1
28800
(default)
DH1
ESP
DES
MD5
28800
(default)
37-13