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PUBLIC KEY CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2.

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Presentation on theme: "PUBLIC KEY CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2."— Presentation transcript:

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2 PUBLIC KEY CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2

3 ElGamal Encryption: Based on Diffie Hellman Key Exchange Cryptography 6/05/2014 | pag. 3 Security of Diffie Hellman key exchange not based on integer factoring (like RSA and Rabin) but on the discrete logarithm problem (DLP).

4 Discrete Logarithm Cryptography 6/05/2014 | pag. 4

5 Diffie Hellman Key Exchange Cryptography 6/05/2014 | pag. 5

6 Diffie Hellman Key Exchange Cryptography 6/05/2014 | pag. 6 Choose order g at least 2^160 to prevent Pohlig Hellman.

7 ElGamal Key Generation Cryptography 6/05/2014 | pag. 7

8 ElGamal Key Encryption Cryptography 6/05/2014 | pag. 8

9 ElGamal Key Decryption Cryptography 6/05/2014 | pag. 9

10 ElGamal Cryptography 6/05/2014 | pag. 10

11 ElGamal and Diffie Hellman Cryptography 6/05/2014 | pag. 11

12 HASH FUNCTIONS Symmetric Cryptosystems 6/05/2014 | pag. 12

13 Hash Function Cryptography 6/05/2014 | pag. 13

14 Compression Function Cryptography 6/05/2014 | pag. 14

15 One-way Function Cryptography 6/05/2014 | pag. 15

16 One-way Function Cryptography 6/05/2014 | pag. 16

17 Collisions Cryptography 6/05/2014 | pag. 17

18 Collisions Cryptography 6/05/2014 | pag. 18

19 Collisions Cryptography 6/05/2014 | pag. 19

20 Compression function from encryption functions Cryptography 6/05/2014 | pag. 20

21 Compression function from encryption functions Cryptography 6/05/2014 | pag. 21

22 Hash functions from compression functions Cryptography 6/05/2014 | pag. 22

23 SHA-1 Cryptography 6/05/2014 | pag The original length of x is written as a 64-bit number. 4. Append 3. to x from 2.

24 SHA-1 Cryptography 6/05/2014 | pag. 24

25 SHA-1 Cryptography 6/05/2014 | pag. 25

26 SHA-1 Cryptography 6/05/2014 | pag. 26

27 Message Authentication Codes Cryptography 6/05/2014 | pag. 27

28 Message Authentication Codes Cryptography 6/05/2014 | pag. 28

29 Message Authentication Codes Cryptography 6/05/2014 | pag. 29

30 Message Authentication Codes Cryptography 6/05/2014 | pag. 30

31 DIGITAL SIGNATURES & IDENTIFICATION Symmetric Cryptosystems 6/05/2014 | pag. 31

32 Digital Signatures Cryptography 6/05/2014 | pag. 32

33 RSA Signatures Cryptography 6/05/2014 | pag. 33 Key Generation:

34 RSA Signatures Cryptography 6/05/2014 | pag. 34 Signature Generation:

35 RSA Signatures Cryptography 6/05/2014 | pag. 35 Signature Verification:

36 RSA Signatures Cryptography 6/05/2014 | pag. 36

37 RSA Signatures with Hash Functions Cryptography 6/05/2014 | pag. 37

38 Other Public Key Digital Signatures Cryptography 6/05/2014 | pag. 38

39 ElGamal Signatures Cryptography 6/05/2014 | pag. 39 Key Generation:

40 ElGamal Signatures Cryptography 6/05/2014 | pag. 40 Signature Generation:

41 Cryptography 6/05/2014 | pag. 41 Signature Verification: ElGamal Signatures

42 Cryptography 6/05/2014 | pag. 42

43 Identification Cryptography 6/05/2014 | pag. 43

44 Identification Cryptography 6/05/2014 | pag. 44 One can use for example Passwords Challenge-Response identification based on symmetric encryption public key encryption Zero-knowledge proofs

45 MULTIMEDIA: CRYPTO IS NOT ENOUGH Symmetric Cryptosystems 6/05/2014 | pag. 45


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