Crypto U8 (part 1), Randomness

Mind Map by , created over 6 years ago

IYM002 (Unit 8 - randomness, freshness, AKE) Mind Map on Crypto U8 (part 1), Randomness, created by jjanesko on 04/22/2013.

Created by jjanesko over 6 years ago
Crypto U4, Block Cipher, Cipher Block Chaining Mode (CBC)
Crypto U3, Theoretical vs. Practical Security
Crypto U1, Basic Principles
The Heart
Art styles
Sarah Egan
Crypto U8, example dynamic password scheme
Crypto U8 (part 2), Freshness
Crypto U8 (part 3), entity authentication
Crypto U4, Block Cipher, Cipher Feedback Mode (CFB)
Crypto U4, Block Cipher, Electronic Codebook Mode (ECB)
Crypto U8 (part 1), Randomness
1 meaning
1.1 uncertainty
1.2 unpredictability
1.3 have no relation to previous chosen numbers
1.4 have no obvious structure
2 randomn values in cryptography
2.1 salt
2.1.1 random data that are used as an additional input to a one-way function that hashes a password or passphrase. ex. Unix password file
2.2 IVs (initialization vector)
2.2.1 a fixed-size input to a cryptographic primitive that is typically required to be random or pseudorandom. ex. cipher block chaining mode
2.3 values used for freshness checks in cryptographic protocols
2.3.1 nonce = number used only once sender sends randomly generated nonce to receiver, receiver sends nonce back with reply to show reply belongs to the original message
2.4 random numbers used to generate symmetric keys
2.4.1 random process are used to generate keys non-deterministic is better than pseudorandom for master keys
2.5 somehow required in El Gamal, but don't understand why
3 What should seem random?
3.1 keystreams
3.2 hash codes
3.3 ciphertexts
4 generating random numbers
4.1 non-deterministic
4.1.1 advantages and disadvantages expensive completely random cannot replicate in another location (so tough to synchronize)
4.1.2 based on randomess proced by physical phenomena hardware measurement of white noise from electrical appliances quantum measurement of a photon reflected in a mirror software keystroke captures hard drive seek times
4.2 deterministic (pseudorandom)
4.2.1 how does it work? takes a seed value and outputs a string of bits with no apparent structure 2 parts seed should be different every time & not guessable usually short usually a "standard" length (like 128 bits) generator use standard, well known ones (nothing home made)
4.2.2 advantages and disadvantages cheap to implement two identical outputs can be generated in 2 different locations (synchronizable) have to find way to distribute seed

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