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Chapter 21 IPSec
VSG1435-B101 Series User’s Guide
260
21.4 Technical Reference
This section provides some technical background information about the topics
covered in this chapter.
Encryption
Algorithm
Select DES, 3DES, AES(aes-cbc) or ESP_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(aes-cbc) in Cipher Block
Chaining (CBC) mode uses a 128-bit key. AES is faster than 3DES.
Select ESP_NULL to set up a tunnel without encryption. When you
select ESP_NULL, you do not enter an encryption key.
Encryption Key Type 16 hexadecimal ("0-9", "A-F") characters if you select to use the
DES encryption algorithm or 48 hexadecimal characters if you use the
3DES encryption algorithm.
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 SHA1 for maximum security.
Authentication
Key
Type 32 hexadecimal ("0-9", "A-F") characters if you select to use the
MD5 authentication algorithm or 40 hexadecimal characters if you use
the SHA1 authentication algorithm.
SPI Type a hexadecimal number from 111 to FFFFFFFF for the Security
Parameter Index.
Apply Click Apply/Save to save your changes and return to the IPSec
screen.
Cancel Click Cancel to exit this screen without saving.
Table 88 IPSec Settings > Add/Edit: Manual
LABEL DESCRIPTION