Atlantis A02-RA340, User Manual, Page: 66 / 85

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options, DES , 3DES , AES (128, 192 and 256) and NULL . NULL means it is a tunnel only
with no encryption. 3DES and AES are more powerful but increase latency.
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DES: Stands for Data Encryption Standard, it uses 56 bits as an encryption method.
•
3DES: Stands for Triple Data Encryption Standard, it uses 168 (56*3) bits as an
encryption method.
•
AES: Stands for Advanced Encryption Standards, you can use 128, 192 or 256 bits as
encryption method.
Perfect Forward Secrecy: Choose whether to enable PFS using Diffie-Hellman public-key
cryptography to change encryption keys during the second phase of VPN negotiation. This
function will provide better security, but extends the VPN negotiation time. Diffie-Hellman is a
public-key cryptography protocol that allows two parties to establish a shared secret over an
unsecured communication channel (i.e. over the Internet). There are three modes, MODP
768-bit,
MODP 1024-bit and MODP 1536-bit. MODP stands for Modular Exponentiation Groups.
Pre-shared Key: This is for the Internet Key Exchange (IKE) protocol, a string from 4 to 128
characters. Both sides should use the same key. IKE is used to establish a shared security
policy
and authenticated keys for services (such as IPSec) that require a key. Before any IPSec
traffic
can be passed, each router must be able to verify the identity of its peer. This can be done by
manually entering the pre-shared key into both sides (router or hosts).
Select the
Apply button to apply your changes.