Applied Cryptography Manoj Prabhakaran University of Illinois Urbana-Champaign Lecture 0 1
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Applied Cryptography
Manoj PrabhakaranUniversity of Illinois Urbana-Champaign
Lecture 0
1
What is Cryptography?
2
What is Cryptography?
It’s all about controlling access to information
2
What is Cryptography?
It’s all about controlling access to information
Access to learning and/or influencing information
2
What is Cryptography?
It’s all about controlling access to information
Access to learning and/or influencing information
Do we know what we are talking about?
2
What is information?
3
What is information?
Or rather the lack of it?
3
What is information?
Or rather the lack of it?
Uncertainty
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
Borrowed from thermodynamics
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
Borrowed from thermodynamics
Rudolf Clausius
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
Borrowed from thermodynamics
Rudolf Clausius
Ludwig Boltzmann
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
Borrowed from thermodynamics
Rudolf Clausius
Ludwig Boltzmann
Claude Shannon
3
What is information?
Or rather the lack of it?
Uncertainty
The word is Entropy
Borrowed from thermodynamics
An inherently “probabilistic” notion
Rudolf Clausius
Ludwig Boltzmann
Claude Shannon
3
What is information?
Claude Shannon
4
What is information?Information Theory: ways to quantify information
Claude Shannon
4
What is information?Information Theory: ways to quantify information
Application 1: to study efficiency of communication (compression, error-correction)
Claude Shannon
4
What is information?Information Theory: ways to quantify information
Application 1: to study efficiency of communication (compression, error-correction)Application 2: to study the possibility of secret communication
Claude Shannon
4
What is information?Information Theory: ways to quantify information
Application 1: to study efficiency of communication (compression, error-correction)Application 2: to study the possibility of secret communication
The latter turned out to be a relatively easy question! Secret communication possible only if (an equally long) secret key is shared ahead of time
Claude Shannon
4
Access to Information
5
Access to InformationA second look
5
Access to InformationA second look
Information at hand may still not be “accessible” if it is hard to work with it
5
Access to InformationA second look
Information at hand may still not be “accessible” if it is hard to work with it
Computation!
5
Access to InformationA second look
Information at hand may still not be “accessible” if it is hard to work with it
Computation!
Shannon’s information may reduce uncertainty only for computationally all-powerful parties
5
Computational Complexity
6
Computational Complexity
A systematic study of what computationally bounded parties can and cannot do
6
Computational Complexity
A systematic study of what computationally bounded parties can and cannot do
A young and rich field
Alan Turing
Stephen Cook
Leonid Levin Richard Karp
6
Computational Complexity
A systematic study of what computationally bounded parties can and cannot do
A young and rich field
Much known, much more unknown
Alan Turing
Stephen Cook
Leonid Levin Richard Karp
6
Computational Complexity
A systematic study of what computationally bounded parties can and cannot do
A young and rich field
Much known, much more unknown
Much “believed”
Alan Turing
Stephen Cook
Leonid Levin Richard Karp
6
Computational Complexity
A systematic study of what computationally bounded parties can and cannot do
A young and rich field
Much known, much more unknown
Much “believed”
Alan Turing
Stephen Cook
Leonid Levin Richard Karp
Basis of the Modern Theory of Cryptography6
Compressed Secret-Keys
7
Compressed Secret-Keys
Pseudo-random number generator
7
Compressed Secret-Keys
Pseudo-random number generator
a.k.a Stream Cipher
7
Compressed Secret-Keys
Pseudo-random number generator
a.k.a Stream Cipher
Generate a long string of random-looking bits from a short random seed
7
Compressed Secret-Keys
Pseudo-random number generator
a.k.a Stream Cipher
Generate a long string of random-looking bits from a short random seed
Impossible in the information-theoretic sense
7
Compressed Secret-Keys
Pseudo-random number generator
a.k.a Stream Cipher
Generate a long string of random-looking bits from a short random seed
Impossible in the information-theoretic sense
But possible against computationally bounded players!
Andy YaoManuel Blum
7
The Public-Key Revolution
8
The Public-Key Revolution“Non-Secret Encryption”
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
James Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
James Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Clifford CocksJames Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Clifford Cocks
Malcolm Williamson
James Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Publicly verifiable digital signatures
Clifford Cocks
Malcolm Williamson
James Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Publicly verifiable digital signatures
Clifford Cocks
Malcolm Williamson
Merkle, Hellman, Diffie
James Ellis
8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Publicly verifiable digital signatures
Clifford Cocks
Malcolm Williamson
Merkle, Hellman, Diffie
James Ellis
Shamir, Rivest, Adleman8
The Public-Key Revolution“Non-Secret Encryption”
No a priori shared secrets
Instead, a public key. Anyone can create encryptions, only the creator of the key can decrypt!
Publicly verifiable digital signatures
Forms the backbone of today’s secure communication
Clifford Cocks
Malcolm Williamson
Merkle, Hellman, Diffie
James Ellis
Shamir, Rivest, Adleman8
Crypto-Mania
9
Crypto-ManiaPublic-Key cryptography and beyond!
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
Compute on distributed data, without revealing their private information to each other
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
Compute on distributed data, without revealing their private information to each otherCompute on encrypted data
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
Compute on distributed data, without revealing their private information to each otherCompute on encrypted data
And other fancy things... with sophisticated control over more complex “access” to information
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
Compute on distributed data, without revealing their private information to each otherCompute on encrypted data
And other fancy things... with sophisticated control over more complex “access” to informationDo it all faster, better, more conveniently and more securely (or find out if one cannot). And also make sure we know what we are trying to do.
9
Crypto-ManiaPublic-Key cryptography and beyond!Secret computation: collaboration among mutually distrusting parties
Compute on distributed data, without revealing their private information to each otherCompute on encrypted data
And other fancy things... with sophisticated control over more complex “access” to informationDo it all faster, better, more conveniently and more securely (or find out if one cannot). And also make sure we know what we are trying to do.
9
10
10
Independence, Indistinguishability, Infeasibility, Zero-Knowledge, ...
10
Independence, Indistinguishability, Infeasibility, Zero-Knowledge, ...
Encryption,
Authentication
10
Independence, Indistinguishability, Infeasibility, Zero-Knowledge, ...
Encryption,
Authentication
DES, AES,
SHA, HMAC
10
Independence, Indistinguishability, Infeasibility, Zero-Knowledge, ...
RSA,
ellip
tic cur
ve
grou
ps, lat
tices
, ...
Encryption,
Authentication
DES, AES,
SHA, HMAC
10
Independence, Indistinguishability, Infeasibility, Zero-Knowledge, ...
one-
way
fun
ctions
, co
llisio
n-re
sista
nt h
ash
func
tion
s, ...
Sema
ntic
secu
rity,
non-
malle
abilit
y, ex
isten
tial
unfo
rgea
bility
...
Obfuscati
on, Leak
age
resilient
crypto,
Imperfect
randomness
, ...
RSA,
ellip
tic cur
ve
grou
ps, lat
tices
, ...
PK Encryption,
Signatures
Encryption,
Authentication
Stre
am c
ipher
s, Bloc
k cip
hers
Pseu
dora
ndom
ness
ge
nera
tors
, PRF
, ...
Random Oracle Model, Generic group model
SSL, TS
L
Iden
tity-
Base
d En
cryp
tion
Secure Multi-Party Computation
Secret sharing,
Verifiable Secret
sharing
ZK proofs
Concrete cryptanalysis
(Birthday attacks,
differential cryptanalysis, ...)
Blind signatures,
Mix-nets, DC-nets,...
e-cash, e-Voting,
Fair Exchange, Privacy
Preserving Datamining, ...
DES, AES,
SHA, HMACHy
brid
enc
rypt
ion
Algo
rithm
s, Re
duct
ions
Malware, DDoS,
Side-channels
Universal com
position
Signcry
ption
Form
al
met
hods
10
In This Course
11
In This Course(how to tame the elephant...)
11
In This CourseFundamental notions of secrecy and infeasibility
(how to tame the elephant...)
11
In This CourseFundamental notions of secrecy and infeasibility
Secure communication (encryption, authentication): definitions, building blocks, construction
(how to tame the elephant...)
11
In This CourseFundamental notions of secrecy and infeasibility
Secure communication (encryption, authentication): definitions, building blocks, construction
And much more: Secure multi-party computation, computing on encrypted data, bleeding edge crypto, quick and dirty crypto...
(how to tame the elephant...)
11
In This CourseFundamental notions of secrecy and infeasibility
Secure communication (encryption, authentication): definitions, building blocks, construction
And much more: Secure multi-party computation, computing on encrypted data, bleeding edge crypto, quick and dirty crypto...
Project: You can pick a topic for surveying/research, or an implementation project
(how to tame the elephant...)
11
In This CourseFundamental notions of secrecy and infeasibility
Secure communication (encryption, authentication): definitions, building blocks, construction
And much more: Secure multi-party computation, computing on encrypted data, bleeding edge crypto, quick and dirty crypto...
Project: You can pick a topic for surveying/research, or an implementation project
A few assignments
(how to tame the elephant...)
11
In This Course(how to tame the elephant...)
12
In This Course
http://www.cs.illinois.edu/class/fa11/cs598man/
(how to tame the elephant...)
12
In This Course
http://www.cs.illinois.edu/class/fa11/cs598man/
Textbook for first part: Katz and Lindell
(how to tame the elephant...)
12
In This Course
http://www.cs.illinois.edu/class/fa11/cs598man/
Textbook for first part: Katz and Lindell
There’s a blog and a wiki.
(how to tame the elephant...)
12
In This Course
http://www.cs.illinois.edu/class/fa11/cs598man/
Textbook for first part: Katz and Lindell
There’s a blog and a wiki.
Office Hours: TBA
(how to tame the elephant...)
12
Related Documents
