HP VPN Server Appliance sa3110/sa3150/sa3400/sa3450 - Virtual Private Networking Concepts Guide

3DES
Hewlett-Packard Company Virtual Private Networking Concepts Guide
2-7
3DES
3DES3DES
3DES
3DES is a symmetric cryptographic system that uses multiple
passes of the DES algorithm to increase the effective key space
available to the system even further than triple pass DES. Use the
same EDE technique as in Triple Pass DES (page 2-5), except
that 3 different keys are used. Therefore, in pass 3 of Triple Pass
DES, you would select a third key (K3 = 4), which increases the
effective key length from 56 bits for simple DES to 168 bits for
3DES.
The steps for both the triple pass DES technique and the 3DES
technique are illustrated with the simple symmetric
cryptographic system in the following table.
Related
Related Related
Related
Information
InformationInformation
Information
Data Encryption Standard (DES) (page 2-4)
Outer Cipher Block Chaining (CBC) (page 2-8)
Algorithm
AlgorithmAlgorithm
Algorithm
Clear
Clear Clear
Clear
Text
TextText
Text
After
After After
After
First
First First
First
Encrypt
Encrypt Encrypt
Encrypt
E
EE
E
After
After After
After
First
First First
First
Decrypt
Decrypt Decrypt
Decrypt
D
DD
D
After
After After
After
Second
Second Second
Second
Encrypt
Encrypt Encrypt
Encrypt
E
EE
E
Triple Pass DES
(Key Space = 2*26
=52)
AT K1 = 3
DW
K2 = 5
YR
K1 = 3
BU
3DES
(Key Space = 3*26
=78)
AT K1 = 3
DW
K2 = 5
YR
K3 = 4
CV