Esp (Encapsulating Security Payload) Protocol; Table 57 Ah And Esp - ZyXEL Communications Vantage CNM User Manual

Vantage CNM User's Guide
In applications where confidentiality is not required or not sanctioned by government
encryption restrictions, an AH can be employed to ensure integrity. This type of
implementation does not protect the information from dissemination but will allow for
verification of the integrity of the information and authentication of the originator.

11.5.2 ESP (Encapsulating Security Payload) Protocol

The ESP protocol (RFC 2406) provides encryption as well as some of the services offered by
AH. ESP authenticating properties are limited compared to the AH due to the non-inclusion of
the IP header information during the authentication process. However, ESP is sufficient if
only the upper layer protocols need to be authenticated.
An added feature of the ESP is payload padding, which further protects communications by
concealing the size of the packet being transmitted.

Table 57 AH and ESP

Encryption
Authentication
171
ESP
DES (default)
Data Encryption Standard (DES) is a
widely used method of data encryption
using a secret key. DES applies a 56-bit
key to each 64-bit block of data.
3DES
Triple DES (3DES) is a variant of DES,
which iterates three times with three
separate keys (3 x 56 = 168 bits),
effectively doubling the strength of DES.
AES
Advanced Encryption Standard is a
newer method of data encryption that
also uses a secret key. This
implementation of AES applies a 128-bit
key to 128-bit blocks of data. AES is
faster than 3DES.
Select NULL to set up a phase 2 tunnel
without encryption.
MD5 (default)
MD5 (Message Digest 5) produces a
128-bit digest to authenticate packet
data.
SHA1
SHA1 (Secure Hash Algorithm) produces
a 160-bit digest to authenticate packet
data.
Select MD5 for minimal security and SHA-1 for maximum security.
AH
MD5 (default)
MD5 (Message Digest 5) produces a
128-bit digest to authenticate packet
data.
SHA1
SHA1 (Secure Hash Algorithm) produces
a 160-bit digest to authenticate packet
data.
Chapter 11 Configuration > VPN