09 - Pseudorandom Permutations Introduction Ciphers and...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Introduction Pseudorandom Permutations and Block Ciphers Cryptography and Protocols Andrei Bulatov
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cryptography and Protocols – Block Ciphers 9-2 Pseudorandom Permutations A pseudorandom function is called a pseudorandom permutation if is one-to-one for all s. The only exception is that when considering security we use random permutations rather than random functions An encryption scheme based on a PRP is called a block cipher * } 1 , 0 { } { = s s f F m m s f } 1 , 0 { } 1 , 0 { :
Background image of page 2
Cryptography and Protocols – Block Ciphers 9-3 DES DES – Data Encryption Standard 1972 NIST (then NBS) called for encryption standards proposals 1974 IBM responded with Lucifer NSA tweaked Lucifer to get DES key size |s| = 56, block size 64 bit 1970’s Diffie & Hellman suggested a $20 million machine to find a key within a day 1990’s Wiener suggests a $1 million to find a key in 3.5 hours 1997 over the Internet ~ $50K machines found a key in 90 days 1998 $210K machine Deep Crack finds a key in 56 hours
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cryptography and Protocols – Block Ciphers 9-4 DES (cntd)
Background image of page 4
Cryptography and Protocols – Block Ciphers 9-5 Modes of Block Ciphers – ECB ECB stands for Electronic CodeBook P plaintext 1 P 2 P 3 P k f 1 C k f 2 C k f 3 C
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 14

09 - Pseudorandom Permutations Introduction Ciphers and...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online