CS.202: Intro to Cryptography
Tuesday, 10/11/2016
Homework 3
Due Wednesday, 10/19/2016, at the beginning of the class
Notation: Let a and b be bitstrings. a|b stands for the concatenation of a and b, |a|
stands for the bitlength of a, ai stands for the i-

CS.202: Intro to Cryptography
10/17/2016
Handout for Problem Set 3
Notation: Let a and b be bitstrings. a|b stands for the concatenation of a and b, |a|
stands for the bitlength of a, ai stands for the i-th bit of a, a[i,j] for i, j cfw_1, ., |a| s.t.
i j

CS.202: Intro to Cryptography
Thursday, 10/27/2016
Homework 4
Due Monday, 11/7/2016, at the beginning of the class
1
CCA insecurity of OFB and CBC modes
Show that OFB and CBC modes of block cipher operation are not not CCA-secure. In
each case you can sho

ICS.202: Introduction to Applied Cryptography
9/28/2016
Homework 1
Due Wednesday, 10/5/2016, at the beginning of the class
Notation: If a is a string then |a| denotes its length. For example |ab| = 2, |abcd| =
4, |01| = 2, |010| = 3, etc. If a, b are stri