PUBLIC KEY CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2.
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Transcript of PUBLIC KEY CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2.
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Public KeyCryptosystems
Symmetric Cryptosystems10/04/23 | pag. 2
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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).
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Discrete Logarithm
Cryptography 10/04/23 | pag. 4
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Diffie Hellman Key Exchange
Cryptography 10/04/23 | pag. 5
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Diffie Hellman Key Exchange
Cryptography 10/04/23 | pag. 6
Choose order g at least 2^160 to prevent Pohlig Hellman.
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ElGamal Key Generation
Cryptography 10/04/23 | pag. 7
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ElGamal Key Encryption
Cryptography 10/04/23 | pag. 8
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ElGamal Key Decryption
Cryptography 10/04/23 | pag. 9
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ElGamal
Cryptography 10/04/23 | pag. 10
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ElGamal and Diffie Hellman
Cryptography 10/04/23 | pag. 11
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Hash functions
Symmetric Cryptosystems10/04/23 | pag. 12
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Hash Function
Cryptography 10/04/23 | pag. 13
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Compression Function
Cryptography 10/04/23 | pag. 14
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One-way Function
Cryptography 10/04/23 | pag. 15
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One-way Function
Cryptography 10/04/23 | pag. 16
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Collisions
Cryptography 10/04/23 | pag. 17
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Collisions
Cryptography 10/04/23 | pag. 18
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Collisions
Cryptography 10/04/23 | pag. 19
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Compression function from encryption functions
Cryptography 10/04/23 | pag. 20
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Compression function from encryption functions
Cryptography 10/04/23 | pag. 21
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Hash functions fromcompression functions
Cryptography 10/04/23 | pag. 22
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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.
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SHA-1
Cryptography 10/04/23 | pag. 24
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SHA-1
Cryptography 10/04/23 | pag. 25
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SHA-1
Cryptography 10/04/23 | pag. 26
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Message Authentication Codes
Cryptography 10/04/23 | pag. 27
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Message Authentication Codes
Cryptography 10/04/23 | pag. 28
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Message Authentication Codes
Cryptography 10/04/23 | pag. 29
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Message Authentication Codes
Cryptography 10/04/23 | pag. 30
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Digital Signatures & Identification
Symmetric Cryptosystems10/04/23 | pag. 31
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Digital Signatures
Cryptography 10/04/23 | pag. 32
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RSA Signatures
Cryptography 10/04/23 | pag. 33
Key Generation:
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RSA Signatures
Cryptography 10/04/23 | pag. 34
Signature Generation:
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RSA Signatures
Cryptography 10/04/23 | pag. 35
Signature Verification:
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RSA Signatures
Cryptography 10/04/23 | pag. 36
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RSA Signatures with Hash Functions
Cryptography 10/04/23 | pag. 37
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Other Public Key Digital Signatures
Cryptography 10/04/23 | pag. 38
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ElGamal Signatures
Cryptography 10/04/23 | pag. 39
Key Generation:
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ElGamal Signatures
Cryptography 10/04/23 | pag. 40
Signature Generation:
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Cryptography 10/04/23 | pag. 41
Signature Verification:
ElGamal Signatures
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ElGamal Signatures
Cryptography 10/04/23 | pag. 42
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Identification
Cryptography 10/04/23 | pag. 43
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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
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Multimedia: crypto is not enough
Symmetric Cryptosystems10/04/23 | pag. 45