Computer Security and Cryptography

8.14 STREAM ENCIPHERMENT PROBLEMS

I have always included one cribbing problem each time I have taught. Until Spring 2005, the plaintext was the Class_List in the format

Class_List
0.	Bostrom, Eric
1.	Isaac, Joshua
2.	Piasecki, David
3.	Bautista, Maria
57.	Chang, Yao-Yin
58.	Julian, Vincenzo
59.	Riggs, David

with some permutation of the alphabetical order of the names. A N-stage LFSR (7 ≤ N ≤ 9), a primitive characteristic generating polynomial p(z), and an initial state have been used to stream encipher the concatenated variable length records in Class_List. In Spring 2005, I enciphered one of the 10 amendments forming the Bill of Rights and challenged the students to identify which one.