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

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

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

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).

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

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

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

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

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

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

ElGamal Cryptography 6/05/2014 | pag. 10

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

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

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

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

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

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

Collisions Cryptography 6/05/2014 | pag. 17

Collisions Cryptography 6/05/2014 | pag. 18

Collisions Cryptography 6/05/2014 | pag. 19

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Cryptography 6/05/2014 | pag. 42

Identification Cryptography 6/05/2014 | pag. 43

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

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