MCS 223 Cryptography Exam 3
Monday, January 26
This will be a closed-book exam.
You may, however, use one new 3"-by-5" note card,
the previous exams' note cards, and a calculator.
Cryptanalysis aids, such as tables of characteristic frequencies,
will be provided.
You will have the entire class period to work the exam,
but you should not need all that time.
You should be prepared to solve problems of the following kinds.
- Encipher/decipher Playfair messages based on a 5-by-5 square
constructed from a keyword.
- Encipher/decipher messages using Hill's digraphic system.
- Solve crypts in Hill's digraphic system.
- Carry out matrix operations,
particularly multiplying and finding inverses,
especially modulo 26.
- Solve linear congruences,
including systems of simultaneous linear congruences.
- Encipher/decipher columnar transposition ciphers.
- Use frequency data, index of coincidence calculations,
and Kasiski evidence to help recognize the system of
encipherment--monoalphabetic, polyalphabetic, or polygraphic.
Primary references for study are your class notes and Sinkov sections
4.1-5.1, 5.3.
Secondary reference: Barr sections 2.4-2.9
Return home.