kefalaio 8 diaxeirish kai asfaleia diktyou 8 3 4 texnikes asfaleias symmetrikh asymmetrikh...

8/7/2019 Kefalaio 8 Diaxeirish Kai Asfaleia Diktyou 8 3 4 Texnikes Asfaleias Symmetrikh Asymmetrikh Kryptografish Pshfiakes Ypografes

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8

8.3.4

. 320-325 19, ggiannop (at)

sch.gr

http://diktya-epal-g.ggia.info/Creative Commons License 3.0 Share-Alike
http://diktya-epal-g.ggia.info/http://diktya-epal-g.ggia.info/


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.

.


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(Encryption):

( plaintext) () . , . .

(Decryption): . () ( )

.

el.wikipedia.org/wiki/
http://el.wikipedia.org/wiki/%CE%9A%CF%81%CF%85%CF%80%CF%84%CE%BF%CE%B3%CF%81%CE%B1%CF%86%CE%AF%CE%B1http://el.wikipedia.org/wiki/%CE%9A%CF%81%CF%85%CF%80%CF%84%CE%BF%CE%B3%CF%81%CE%B1%CF%86%CE%AF%CE%B1http://el.wikipedia.org/wiki/%CE%9A%CF%81%CF%85%CF%80%CF%84%CE%BF%CE%B3%CF%81%CE%B1%CF%86%CE%AF%CE%B1


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.

. . Caesar Cipher

( ) .

: 3


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CaesarCipher

24 ( ).

, . () =>

. ( )

(;).


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CSS (Content Scramble System) DVD, A5/1 , BD+ Blue Ray (.. Anydvd Slysoft).

( ) !

http://en.wikipedia.org/wiki/Content_Scramble_S

http://en.wikipedia.org/wiki/A5/1http://en.wikipedia.org/wiki/BD%2B

http://commons.wikimedia.org/wiki/File:BluRayDiscBack.png
http://commons.wikimedia.org/wiki/File:BluRayDiscBack.pnghttp://en.wikipedia.org/wiki/Content_Scramble_Systemhttp://en.wikipedia.org/wiki/A5/1http://en.wikipedia.org/wiki/BD%2Bhttp://commons.wikimedia.org/wiki/File:BluRayDiscBack.pnghttp://commons.wikimedia.org/wiki/File:BluRayDiscBack.pnghttp://en.wikipedia.org/wiki/BD%2Bhttp://en.wikipedia.org/wiki/A5/1http://en.wikipedia.org/wiki/Content_Scramble_System


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DES (Data Encryption Standard): .3DES (Triple DES): DES.

IDEA (International Data EncryptionAlgorithm): .

64bits. 64bits 64bits.


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. 2

.

. .


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Alice Bob

. . ( keyservers). ( )

.

AliceBob


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(Key): , ( bits) . .

(Public Key): , , .

, . () . , .

en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpg
http://en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpghttp://en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpg


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. 323 , .

keyservers

. . (fingerprint), .

(.. ) !

.


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Alice Bob. Bob , Bob . ( Bob) ( ,

Bob Bob).

Alice Bob


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O Bob Alice Alice ; Alice . Bob Alice Bob

Alice.

Alice Bob


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. ,

(smart cards).

( ).

RSA (Rivest, Shamir, Adelman) ELGamal:

en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpg http://en.wikipedia.org/wiki/File:Public-key-crypt
http://en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpghttp://en.wikipedia.org/wiki/File:Public-key-crypto-1.svghttp://en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpghttp://en.wikipedia.org/wiki/File:Public-key-crypto-1.svghttp://en.wikipedia.org/wiki/File:Public-key-crypto-1.svghttp://en.wikipedia.org/wiki/File:RSA_SecurID_SID800.jpg


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.

(Digital Signature): bit ( ) ( ) .

() (HashFunction): ( )

. , ,

(digests). commons.wikimedia.org/wiki/File:Hash_functio
http://commons.wikimedia.org/wiki/File:Hash_function_el.svghttp://commons.wikimedia.org/wiki/File:Hash_function_el.svg


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( ).

. : Message

Digest 4 (MD4), Message Digest 5 (MD5),Secure Hash Algorithm (SHA).

:


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(.. Bob Alice)

( , .. PGP, Digital Signature Standard) (.. MD5). . . Alice Bob

. (digest). , . Bob . O Bob

Alice. , . , , Alice.

.

:


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http://commons.wikimedia.org/wiki/File:Digital_Signature_diag

.
http://commons.wikimedia.org/wiki/File:Digital_Signature_diagram_el.svghttp://commons.wikimedia.org/wiki/File:Digital_Signature_diagram_el.svg


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http://diktia.dyndns.org/ - ' . .

http://el.wikipedia.org/wiki/%CE%A8%CE%B7%CF%86%CE%B9%CE%B1%CE%BA%CE%AE_%CF%85%CF%80%CE%BF%CE%B3%CF%81%CE%B el. wikipedia.
http://diktia.dyndns.org/http://el.wikipedia.org/wiki/%CE%A8%CE%B7%CF%86%CE%B9%CE%B1%CE%BA%CE%AE_%CF%85%CF%80%CE%BF%CE%B3%CF%81%CE%B1%CF%86%CE%AEhttp://el.wikipedia.org/wiki/%CE%A8%CE%B7%CF%86%CE%B9%CE%B1%CE%BA%CE%AE_%CF%85%CF%80%CE%BF%CE%B3%CF%81%CE%B1%CF%86%CE%AEhttp://diktia.dyndns.org/

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