Authenticated encryption
Rohit Chadha
Chadha
Cryptography
1 / 12
Recap
Confidentiality
Only unauthorized party can access the data
Block ciphers achieve CPA security in CTR mode, CBC mode
Integrity
No authorized party can alter the data
CBC-MAC, HMAC
Chad

Introduction to Key Exchange
Rohit Chadha
Chadha
Cryptography
How do Alice and Bob share secret keys
Block ciphers, Macs, authenticated encryption all need Alice
and Bob to share secrets
Chadha
Cryptography
How do Alice and Bob share secret keys
Block cip

More Number Theory
Rohit Chadha
Chadha
Cryptography
1 / 14
Recall: Modulus
For every integer a and a positive integer N, there exist unique numbers q
and r s.t.
a = qN + r
0r <N
We write r = a mod N
1
100 mod 6 = 4
2
18 mod 6 =< 2 > 0
3
3 mod 6 =< 2 > 3
N

Integrity: Message authentication codes (MACs)
Rohit Chadha
Chadha
Cryptography
1 / 28
What is Integrity?
Integrity
No unauthorized party can alter the data
So far, we have only considered confidentiality
Integrity is independent of confidentiality
For no

CMP SC 4460/7460: Introduction to
cryptography
Prerequisites: CS 3050 and MATH 2320. More specifically, the course
will assume a familiarity with discrete math used in computer science, big-O
notation and elementary probability theory.
Course Overview: Cr

Digital signatures
Rohit Chadha
Chadha
Cryptography
Digital signatures
Non-repudiation: A participant should not be able to back out of
their commitment
Scenario
Two parties are involved in a commercial exchange (over the
Internet)
Chadha
Cryptography
Dig