AT-S63 Management Software Features Guide
Section IX: Management Security
417
algorithm and key. For a given input block of plaintext ECB always
produces the same block of ciphertext.
Cipher Block Chaining (CBC)
is the most popular form of DES
encryption. CBC also operates on 64-bit blocks of data, but includes a
feedback step which chains consecutive blocks so that repetitive
plaintext data, such as ASCII blanks, does not yield identical
ciphertext. CBC also introduces a dependency between data blocks
which protects against fraudulent data insertion and replay attacks.
The feedback for the first block of data is provided by a 64-bit
Initialization Vector (IV). This is the DES mode used for the switch’s
data encryption process.
Cipher FeedBack (CFB)
is an additive-stream-cipher method which
uses DES to generate a pseudo-random binary stream that is
combined with the plaintext to produce the ciphertext. The ciphertext is
then fed back to form a portion of the next DES input block.
Output FeedBack (OFB)
combines the first IV DES algorithms with
the plaintext to form ciphertext. The ciphertext is then used as the next
IV.
The DES algorithm has been optimized to produce very high speed
hardware implementations, making it ideal for networks where high
throughput and low latency are essential.
Triple DES Encryption Algorithms
The Triple DES (3DES) encryption algorithm is a simple variant on the
DES CBC algorithm. The DES function is replaced by three rounds of that
function, an encryption followed by a decryption followed by an encryption.
This can be done by using either two DES keys (112-bit key) or three DES
keys (168-bit key).
The two-key algorithm encrypts the data with the first key, decrypts it with
the second key and then encrypts the data again with the first key. The
three-key algorithm uses a different key for each step. The three-key
algorithm is the most secure algorithm due to the long key length.
There are several modes in which Triple DES encryption can be
performed. The two most common modes are:
Inner CBC mode
encrypts the entire packet in CBC mode three times
and requires three different initial is at ion vectors (IV’s).
Outer CBC mode
triple encrypts each 8-byte block of a packet in CBC
mode three times and requires one IV.
Asymmetrical (Public Key) Encryption
Asymmetrical encryption algorithms use two keys—one for encryption and
one for decryption. The encryption key is called the public key because it
cannot be used to decrypt a message and therefore does not need be kept
Содержание AT-S63
Страница 14: ...Figures 14 ...
Страница 18: ...Tables 18 ...
Страница 28: ...28 Section I Basic Operations ...
Страница 58: ...Chapter 1 Overview 58 ...
Страница 76: ...Chapter 2 AT 9400Ts Stacks 76 Section I Basic Operations ...
Страница 96: ...Chapter 5 MAC Address Table 96 Section I Basic Operations ...
Страница 114: ...Chapter 8 Port Mirror 114 Section I Basic Operations ...
Страница 116: ...116 Section II Advanced Operations ...
Страница 146: ...Chapter 12 Access Control Lists 146 Section II Advanced Operations ...
Страница 176: ...Chapter 14 Quality of Service 176 Section II Advanced Operations ...
Страница 196: ...196 Section III Snooping Protocols ...
Страница 204: ...Chapter 18 Multicast Listener Discovery Snooping 204 Section III Snooping Protocols ...
Страница 216: ...Chapter 20 Ethernet Protection Switching Ring Snooping 216 Section III Snooping Protocols ...
Страница 218: ...218 Section IV SNMPv3 ...
Страница 234: ...234 Section V Spanning Tree Protocols ...
Страница 268: ...268 Section VI Virtual LANs ...
Страница 306: ...Chapter 27 Protected Ports VLANs 306 Section VI Virtual LANs ...
Страница 320: ...320 Section VII Internet Protocol Routing ...
Страница 360: ...Chapter 30 BOOTP Relay Agent 360 Section VII Routing ...
Страница 370: ...Chapter 31 Virtual Router Redundancy Protocol 370 Section VII Routing ...
Страница 372: ...372 Section VIII Port Security ...
Страница 402: ...Chapter 33 802 1x Port based Network Access Control 402 Section VIII Port Security ...
Страница 404: ...404 Section IX Management Security ...
Страница 436: ...Chapter 36 PKI Certificates and SSL 436 Section IX Management Security ...
Страница 454: ...Chapter 38 TACACS and RADIUS Protocols 454 Section IX Management Security ...
Страница 462: ...Chapter 39 Management Access Control List 462 Section IX Management Security ...
Страница 504: ...Appendix B SNMPv3 Configuration Examples 504 Security Model Security Level Storage Type SNMPv3 Parameters Continued ...
Страница 532: ...Appendix D MIB Objects 532 ...