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Welcome to CS 355: Topics in Cryptography — Spring 2026! Please note this is different from CS 355 offered last year. See this offering’s schedule for more details.

Organization and Course Policies

Attendance

Attendance at lectures is strongly encouraged. In particular, do not enroll in CS 355 if you are taking another course that meets at the same time.

Grading

Each of the five problem sets is worth 20% of your grade. There is no midterm or final exam.

Problem Sets

You must use LaTeX to write up your problem sets using the provided template. All problem sets are due at 6 pm on the listed day, every two weeks. We will post the problem sets about two weeks before their due date.

Problem Set Submission: You must submit your problem set via Gradescope. You should have been automatically added at the start of the quarter if you’re enrolled in the course. Please email us if there’s any issue. Note that Gradescope requires that the solution to each problem starts on a new page.

Late Submissions: You get three “late days” in total during the quarter. You may use a late day to submit a problem set after the deadline via Gradescope. You may only use late days in one-day increments (no partial late days), and you may use at most one late day on the last one (pset 5).

If you submit an assignment more than 72 hours after the deadline, or if you submit an assignment late after running out of late days, you will receive no credit for the submission. Please submit your assignments on time and save your late days for extraordinary circumstances.

Collaboration: You may discuss the problem sets with other students and you may work together to come up with solutions to the problems. If you do so, you must list the name of your collaborators on the first page of your submission. Each student must write up their problem set independently.

LLMs/AI: In this class, LLMs or other AI tools are considered knowledgeable (if fallible) “friends” outside of this class (i.e., they are not collaborators as described above). Thus, you are allowed to interact with them the same way you would with such friends. It is OK to use them to build intuition, get ideas, learn a topic, et cetera but NOT OK to use them to solve an entire problem, write up the solution, and rob you of the joy of learning :(.

You may use the Boneh-Shoup textbook, or any other textbook of your choosing as a reference. If you use a result from a textbook in the course of solving a problem, please cite the textbook in your write-up. Please do not search the Internet for answers to PSet problems.

Academic Honesty

Please follow the Stanford honor code. In this class, the following will be considered violations of the honor code:

  • Having anyone else (including AI, see above) write up your PSet solutions for you, or looking at anyone else’s write-up. This includes looking at any solutions for past offerings of this class that may be floating around. (If you become aware of any such solutions on the internet or elsewhere, please let the course staff know).
  • Providing help to others in violation of the bullet point above.

If you have questions about these policies, please just ask us!

Students with Documented Disabilities

Students who may need an academic accommodation based on the impact of a disability must initiate the request with the Office of Accessible Education (OAE). Professional staff will evaluate the request with required documentation, recommend reasonable accommodations, and prepare an Accommodation Letter for faculty. Unless the student has a temporary disability, Accommodation letters are issued for the entire academic year. Students should contact the OAE as soon as possible since timely notice is needed to coordinate accommodations. The OAE is located at 563 Salvatierra Walk (phone: 650-723-1066, URL: https://oae.stanford.edu).