(one-way function), - (hash function), - (digest function).
- () . , . ( ) , -, -.
- . - h(-) () - h(M)=H . . , - h(M) .
- :
- - ,
, , . .;
- - ,
', -,
;
- , - (
) , .
, , (), (. 3, ). . , , () , , . , , . , .
. . . , , . .
. , , .
. 3.
. 3, . -, , , . , , , . .
|
|
.
. :
- , , - ;
- , .
- MD2, MD4, MD5. 16 . MD4 SHA, 20 . IBM MDC2 MDC4, DES.
( ) . () ( () , (), (), ().
() . , , , . .
,
. :
.
. . , , . .
( ) , , , .
, . , , , : .
|
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. 4. RSA
. 4 RSA. : , , , . S (D, )
S =Td mod n.
(, S). , (, n), , , S
= SE mod n.
, , , , , . , , . . , , .
, . , , : , (. 5).
. 5.
DES. DES RSA, . , , RSA.
:
1. ? ?
2. DES?
3. ?
4. -?
5. ?
:
1. . . . . . . 2009
2. . . . . 2009
17. OSI.
:
1. OSI
2.
3. DHCP
OSI
ISO (International Standardization Organization) OSI (Open System Interconnection). . , .
OSI . .
. . , . , . (traffic) . , .
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|
OSI , .
OSI , . , . OSI 7 :
7. (application layer)
6. (presentation layer)
5. (session layer)
4. (transport layer)
3. (network layer)
2. (data link layer)
1. (physical layer)
. :
- ;
- ;
- ;
- ;
- ;
- .
OSI 2 :
,
,
- -, . . .
, - . - , , -.
. API (Application Programming Interface).
. OSI
. (packet) , .
. (), , ., , .
. , , , . , , .
.
(application layer) - ,
. , .
:
- HTTP ( -)
- FTP (FileTransferProtocol) ;
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|
- TFTP (TrivialFileTransferProtocol) ;
- X.400 ;
- Telnet ;
- SMTP (Simple Mail Transfer Protocol) ;
- CMIP (Common Management Information Protocol) ;
- SLIP (Serial Line IP) IP . ;
- SNMP (Simple Network Management Protocol) ;
- FTAM (File Transfer, Access, and Management) , .
( ; presentationlayer) / . , , , . / /, , .
: ( ) , (). , , SMTP , .. . , ( ).
, , , , JPEG.
() (JPEG, GIF, PNG, TIFF), (ASCII, EBDIC), (MPEG) ..
.
(sessionlayer) , . / , , , . , , , .
, , , . SMPP (Short message peer-to-peer protocol), USSD , PAP (Password Authentication Protocol) .
: ADSP, ASP, H.245, ISO-SP (OSISessionLayerProtocol (X.225, ISO 8327)), iSNS, L2F, L2TP, NetBIOS, PAP, PPTP, RPC, RTCP, SMPP, SCP, ZIP, SDP
, :
- ( );
- ( , ).
, , . , . , .
(transport layer) . () .
(, ) . . , . , .
, UDP , ; TCP , , , , .
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|
- . ? , , (.. 900000 , 24 ).
: (, ) . . 100%, .. , .. . , .
:
- TCP (Transmission Control Protocol) TCP/IP;
- UDP (User Datagram Protocol) TCP/IP;
- NCP (NetWare Core Protocol) NetWare;
- SPX (Sequenced Packet eXchange) Novell;
- TP4 (Transmission Protocol) 4.
UDP , . TCP , , , , .
, , , UDP ( ), , , , .. TCP ( , ).
(networklayer) . (packet). . , ( MAC- ), , , .
.
( - , ) ( OSI).
:
- IP/IPv4/IPv6 (Internet Protocol) Internet, TCP/IP, ;
- IPX (Internetwork Packet Exchange) , Novell;
- X.25 ( 2);
- CLNP (Connection Less Network Protocol) .
- RIP, EIGRP, OSPF
(data link layer) , . , , , , , ( ) . , .
, , , , , . , . , . , .
IEEE (Institute of Electrical and Electronics Engineers - ) : LLC MAC.
LLC (Logical Link Control), .
MAC (Media Access Control), .
, , .. .
:
- PPP (Point-to-Point) .
- FDDI (Fiber Distributed Data Interface) IEEE 802.6, , 200 .
- HDLC (High Level Data Link Control) , ;
- IEEE 802.2 LLC ( I II) MAC 802.x;
- Ethernet IEEE 802.3 , ;
- Token ring IEEE 802.5, ;
- Frame relay , 25 ISDN.
. , . : ODI, NDIS, UDI.
(physicallayer) , , , () . , 0 1 . . / : ; ; 0 1.
:
1. .
2. .
3. , , .
4. .
5. .
, .
, . . , . , , , ..
:
- EIA-RS-232-C, CCITT V.24/V.28 - / .
- EIA-RS-422/449, CCITT V.10 - , .
- IEEE 802.3 -- Ethernet
- IEEE 802.5 -- Token ring
- IEEE 802.15 (Bluetooth)
- Wi-Fi
- IRDA ( )
OSI : , , , .
, , . , FDDI .
, . , .
. , .
, . : , - .