PLANET CS-2001 - Manual (Page 248)

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Terms in VPN
Diffie-Hellman
 A cryptographic protocol that allows two parties that have no perior knowledge
of each other to establish a shared secret key over an insecure communications
channel.
RSA
 The RSA is a kind of asymmetric cryptography. It involves a public and private
key. The public key can be known to everyone and is used for encrypting
messages. Messages encrypted with the public key can only be decrypted using
the private key.
Pre-Shared Key String
 A Pre-Shared Key String is a string of Unicode characters used to authenticate
Layer Two Tunneling Protocol (L2TP) over Internet Protocol security (IPSec)
connections.
ISAKMP (Internet Security Association Key Management Protocol)
 The IP Security Association Key Management Protocol (ISAKMP)
provides the way to create the Security Association (SA) between two PCs. The
SA can access the encoding between two PCs, and the IT administrator can
assign of which key size or Pre-Shared Key String and algorithm to use. The SA
comes in many connection ways, for instance, use the ISAKMP SA between two
PCs, and assign an ENC algorithm (DES, triple DES, 40-bit DES or not using
any) and an authentication method to use.
Main mode
 When associating IKE certificates, the device offers main mode and aggressive
mode to choose from. The main mode requests sending 6 messages mutually
before starting the data exchange, it is to confirm the identity of both parties,
ensuring the data transferring security.
Aggressive mode
 The aggressive mode requests sending 3 messages mutually before starting the
data exchange, it is to confirm the identity of both parties, ensuring the data
transferring security.