You can use e-mail, courier, or overnight express to
send the shared secret keys to the administrators of the devices. But the easiest key
exchange method is a public key exchange method between the encrypting and decrypting
devices. The DH key agreement is a public key exchange method that provides a way for
two peers to establish a shared secret key, which only they know, even though they are
communicating over an insecure channel. Figure 8-12 shows that the shared keys need to
be established securely over an open network.
Figure 8-12 Encryption Keys Must Be Established
Some of the encryption algorithms and the length of keys they use are as follows:
?– Data Encryption Standard (DES) algorithm: DES was developed by IBM. DES
uses a 56-bit key, ensuring high-performance encryption. DES is a symmetric key
cryptosystem.
4ehIDx67N
U78IOPotV
Key
Encryption Key
Key
Decryption Key
Decrypt Encrypt
Pay to Terry Smith $100.00
One Hundred and xx/100 Dollars
Pay to Terry Smith $100.00
One Hundred and xx/100 Dollars
Key
Encryption Key
Key
Decryption Key
Both peers need
to establish a
shared key
securely.
Encrypt Decrypt
Introducing VPN Solutions 311
?– Triple DES (3DES) algorithm: The 3DES algorithm is a variant of the 56-bit DES.
Pages:
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461