53640
Crypto U8 (part 1),
Randomness
- meaning
- uncertainty
- unpredictability
- have no relation to previous chosen numbers
- have no obvious structure
- uncertainty
- randomn values in cryptography
- salt
- random data that are used as an
additional input to a one-way function
that hashes a password or
passphrase.
- ex. Unix password file
- ex. Unix password file
- random data that are used as an
additional input to a one-way function
that hashes a password or
passphrase.
- IVs (initialization
vector)
- a fixed-size input to a
cryptographic primitive that is
typically required to be random
or pseudorandom.
- ex. cipher block chaining mode
- ex. cipher block chaining mode
- a fixed-size input to a
cryptographic primitive that is
typically required to be random
or pseudorandom.
- values used for freshness checks in cryptographic protocols
- 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
- sender sends randomly generated nonce to
receiver, receiver sends nonce back with reply to
show reply belongs to the original message
- nonce = number used only once
- random numbers used to generate symmetric keys
- random process are used to generate keys
- non-deterministic is better than
pseudorandom for master keys
- non-deterministic is better than
pseudorandom for master keys
- random process are used to generate keys
- somehow required in El Gamal, but don't understand why
- salt
- What should seem random?
- keystreams
- hash codes
- ciphertexts
- keystreams
- generating random numbers
- non-deterministic
- advantages and disadvantages
- expensive
- completely random
- cannot replicate in another location (so tough to synchronize)
- expensive
- based on
randomess
proced by
physical
phenomena
- hardware
- measurement of white noise
from electrical appliances
- quantum
measurement of a
photon reflected in
a mirror
- measurement of white noise
from electrical appliances
- software
- keystroke captures
- hard drive seek times
- keystroke captures
- hardware
- advantages and disadvantages
- deterministic (pseudorandom)
- 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)
- should be
different every
time & not
guessable
- generator
- use standard, well
known ones (nothing
home made)
- use standard, well
known ones (nothing
home made)
- seed
- takes a seed value
and outputs a string of
bits with no apparent
structure
- advantages and disadvantages
- cheap to implement
- two identical
outputs can be
generated in 2
different
locations
(synchronizable)
- have to find way to distribute seed
- cheap to implement
- how does it work?
- non-deterministic
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