public key cryptosystems symmetric cryptosystems 6/05/2014 | pag. 2
TRANSCRIPT
Public KeyCryptosystems
Symmetric Cryptosystems10/04/23 | pag. 2
ElGamal Encryption:Based on Diffie Hellman Key Exchange
Cryptography 10/04/23 | 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 10/04/23 | pag. 4
Diffie Hellman Key Exchange
Cryptography 10/04/23 | pag. 5
Diffie Hellman Key Exchange
Cryptography 10/04/23 | pag. 6
Choose order g at least 2^160 to prevent Pohlig Hellman.
ElGamal Key Generation
Cryptography 10/04/23 | pag. 7
ElGamal Key Encryption
Cryptography 10/04/23 | pag. 8
ElGamal Key Decryption
Cryptography 10/04/23 | pag. 9
ElGamal
Cryptography 10/04/23 | pag. 10
ElGamal and Diffie Hellman
Cryptography 10/04/23 | pag. 11
Hash functions
Symmetric Cryptosystems10/04/23 | pag. 12
Hash Function
Cryptography 10/04/23 | pag. 13
Compression Function
Cryptography 10/04/23 | pag. 14
One-way Function
Cryptography 10/04/23 | pag. 15
One-way Function
Cryptography 10/04/23 | pag. 16
Collisions
Cryptography 10/04/23 | pag. 17
Collisions
Cryptography 10/04/23 | pag. 18
Collisions
Cryptography 10/04/23 | pag. 19
Compression function from encryption functions
Cryptography 10/04/23 | pag. 20
Compression function from encryption functions
Cryptography 10/04/23 | pag. 21
Hash functions fromcompression functions
Cryptography 10/04/23 | pag. 22
SHA-1
Cryptography 10/04/23 | 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 10/04/23 | pag. 24
SHA-1
Cryptography 10/04/23 | pag. 25
SHA-1
Cryptography 10/04/23 | pag. 26
Message Authentication Codes
Cryptography 10/04/23 | pag. 27
Message Authentication Codes
Cryptography 10/04/23 | pag. 28
Message Authentication Codes
Cryptography 10/04/23 | pag. 29
Message Authentication Codes
Cryptography 10/04/23 | pag. 30
Digital Signatures & Identification
Symmetric Cryptosystems10/04/23 | pag. 31
Digital Signatures
Cryptography 10/04/23 | pag. 32
RSA Signatures
Cryptography 10/04/23 | pag. 33
Key Generation:
RSA Signatures
Cryptography 10/04/23 | pag. 34
Signature Generation:
RSA Signatures
Cryptography 10/04/23 | pag. 35
Signature Verification:
RSA Signatures
Cryptography 10/04/23 | pag. 36
RSA Signatures with Hash Functions
Cryptography 10/04/23 | pag. 37
Other Public Key Digital Signatures
Cryptography 10/04/23 | pag. 38
ElGamal Signatures
Cryptography 10/04/23 | pag. 39
Key Generation:
ElGamal Signatures
Cryptography 10/04/23 | pag. 40
Signature Generation:
Cryptography 10/04/23 | pag. 41
Signature Verification:
ElGamal Signatures
ElGamal Signatures
Cryptography 10/04/23 | pag. 42
Identification
Cryptography 10/04/23 | pag. 43
Identification
Cryptography 10/04/23 | 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 Cryptosystems10/04/23 | pag. 45