CSC-233: Introduction to Cryptography

Read This Document!

This document is not "boilerplate"! There is a lot of important information that you need to know about this course contained here. This is particularly true for students in online sections. Not only does it give you all kinds of information (e.g. how to register for exams, how to contact the instructor, how to get help, what is required on assignments, etc etc, ), it also reiterates some key rules and policies that you must know.

Again, be sure to read this document and be sure to refer to it as needed throughout the course.

Time and Location

Quarter: WinterQuarter, 2026

Class Time: Tuesdays/Thursdays, 10:10-11:40 // Online

Class Location: CDM-222

Instructor Information

Name: Yosef Mendelsohn

Office Hours: Please see my office hours page.

E-Mail: josephmendelsohn@gmail.com

Important Dates & Course calendar

• First Lecture: Tuesday, January 6th

• Please be SURE to view the following and make note of the key dates: https://academics.depaul.edu/calendar/Pages/default.aspx. In particular, note:

  • Last day to add the course

  • Last day to drop the course without penalty (i.e. tuition charge)

  • Last day to withdraw from the course

• Midterm Exam #1:

  • In-Class Section: Thursday, Jan 29, regular classroom time and location

  • Online Section: Window period from Jan 29-Feb 2nd

• Midterm Exam #2:

  • Tuesday, Feb. 17, regular classroom time and location

  • Online Section: Window period from Feb 17-21

• Final Exam:

  • Thursday March 19, 8:30am-10:45 AM

    • NOTE THE TIME! (It is not the usual class time).

    • Location: Regular classroom

  • Online Section: Window period from March 12-19 (this may change)

Course Description

From the course catalog: "[CSC 233] is an introduction to the science and history of secret writing (cryptography) and how codes and ciphers can be broken (cryptanalysis). In historical settings we will encounter the main ideas and methods devised to secure communication channels. Possible topics include: substitution ciphers, transposition ciphers, the Vigènere cipher, statistical methods in cryptanalysis, public-key cryptography, and quantum cryptography.

Prerequisites

• MAT 120 (or MAT 130 or CSC 241 or CSC 243)

About Your Instructor

My faculty bio can be found here.

Grading Breakdown

Important Notes About Assignment and Exam Scores

• The assignments are for YOU TO LEARN. They are not meant for evaluation which is why they do not form a significant part of your grade.

• *Note that the assignment percentage is less than any one of your exams!* So if you use any outside resources on assignments (e.g generative AI), it is guaranteed that this will result in correspondingly poor results on the exams.

• In Other Words: There is no need to "cheat" on assignments (e.g. by using AI) as they only form a small percentage of your course grade. To reiterate: The assignments in this course are there as tools for YOU to LEARN the material.

• Important: Missing any exam will result in a failing grade for the course.

Grading Scale

Course Policies

Assignments

Due Date and Time: Each programming assignment will have a posted deadline, specified on D2L. I have allowed for a "grace period". This is a 2 day period after the “due” date. (D2L calls this the “end date”) during which you can sumibt your assignments. However, there will be a 3 point (out of 40) deduction for each day the assignment is late. No late assignments are accepted beyond this 2-day extension.

You can resubmit as often as you like: If you make modifications to an assignment that you have already submitted, you are welcome to upload the newer version to D2L provided, of course, that it is uploaded before the assignment deadline. The grader will always grade your most recent submission.

Exams

• The course will be made up of three exams: Midterm #1, Midterm #2, and Final Exam. The date are specified under the "Important Dates" section above.

• Detailed information about exams will be communicated to you as the quarter progresses.

• In-Class Students: For quarters in which there is an in-class section, students in that section MUST take the exam in the classroom at the scheduled date and time. In-class students can not take exams via a proctoring service.

• Online students

  • Be sure to closely read the section called "Exams for Online Students" below.

Exams for Online Students

The following is very important, so please read it carefully!

As online students, your exams will be proctored at DePaul University. For students who live more than 30 miles from DePaul University, exams may be taken at licensed proctoring locations.

• You register for exams through MyCDM. I will send out an email reminder asking you to register as the exam time approaches.

• There are NO options for taking the exam online. The exam must be taken in person using one of the two options as specified in this section.

• Exams must be completed within the window of time provided. It is usually 3-4 days.

• A score of 0 will be recorded for the exam if it is not taken within the timeframe. Makeups will not be offered without very extenuating circumstances, and documentation will always be required. It is not possible to pass the course without taking the exam.

• Exams are required. Students who do miss ANY exam can not receive a passing grade in the course.

• The exam scheduling window will be opened about 2 weeks before the exam week. I will send out a News posting when scheduling is available.

• Be sure to register PROPMTLY for proctored exams since preferred times and locations do fill up!!

  • Again, when you receive the notification that the exam registration has opened, do not delay in registering! If you delay in registering for an exam, and all your preferred time slots are filled up, your only option is to contact the Online Learning staff to see if they can squeeze you in somewhere. Your professor is, unfortunately not able to assist with this as he does not have anything to do with exam proctoring.

  • Under extenuating circumstances, the professor may extend the exam window, but this will come with a significant deduction on the exam. This is not to penalize any one student. Rather it is so that all students are treated fairly, and have the same time period and window in which to take the exam.

  • If there is an important need, I am willing to consider allowing a student to take the exam before the window has opened. But I can not promise. If it is possible, however, I will certainly try to work with you on it.

• Important: When exam time comes around, please be sure to read the online student policies document for detailed information.

• Exams MUST be taken either through DePaul’s online learning proctoring service. For students, who live more than 30 miles away from DePaul University, an exam may be taken at a certified proctoring center.

• If you are unable to accept the course requirement that the exam must be taken at a proctored location (either at DePaul or at a licensed center), then you must not register for this course. No exceptions will be given. Please note that this is university policy (not my personal policy).

• Important: All questions relating to online exams should be directed to the online learning staff. That is, please do not contact me with questions about online exams. The online learning staff can be reached at olstaff@cdm.depaul.edu The reason you should contact the OL staff instead of me is that I do not have anything to do with the organization or scheduling of online exams. All of this is handled by CDM’s online learning staff.

  • For example, if you need to modify an existing exam reservation (i.e. change day or time), please email olstaff@cdm.depaul.edu if the Exam App prevents you from making changes

How to Contact Me

My students are always my #1 priority, so I try to check emails frequently throughout the day. Sometimes I can reply to emails within an hour or two, sometimes it take several hours before I get to them. However, I do make every attempt to answer all emails within 24 hours. In the event that this does not happen, please do feel free to resend the email. You don't have to "apologize for disturbing" me as the fault is mine! I will never ignore an email from you. Therefore, if you do not receive a response from me, you may assume that the email got lost in the pile somewhere or ended up in my spam folder. In that case, please do resend it.**

When e-mailing me, it is very important that you include your name and course number in the subject. I have a pretty stringent spam-filter on my e-mail, so if you don’t do this, your e-mail may well end up in my spam folder. For example:**

Subject: Smith, csc-401, absence from lecture

Real-Time Communication

In addition to office hours, I am more than happy to speak with students by Zoom or by phone. If you wish to schedule an appointment, please email me at least 2-3 times that are good for you, and I will email you back with an appointment. However, office hours is strongly encouraged. Obviously for online students, it may be more practical to have phone or online meetings.

Pronoun / Name Preferences

Professional courtesy and sensitivity are especially important with respect to individuals and topics dealing with differences of race, culture, religion, politics, sexual orientation, gender, gender variance, and nationalities. I will gladly honor your request to address you by an alternate name or gender pronoun. Please advise me of this preference early in the quarter so that I may make appropriate changes to my records. Please also note that students may choose to identify within the University community with a preferred first name that differs from their legal name and may also update their gender. The preferred first name will appear in University related systems and documents except where the use of the legal name is necessitated or required by University business or legal need. For more information and instructions on how to do so, please see the Student Preferred Name and Gender Policy at http://policies.depaul.edu/policy/policy.aspx?pid=332

Getting Help in the Course

D2L Discussion Forum: Post course content questions to the D2L forum so I can answer you and share the answer with the class. NOTE: Posting to the discussion forum is the preferred way to ask for help or clarifications. There are many reasons why it is better than emailing me including:

• Someone else in the class might answer you before I do. Your pforessor absolultey loves it when students help each other out!!

• The professor am continually monitoring the forum. Therefore, I will always reply to questions that are posted. (Though I won’t of course simply give away answers or things like that!)

• By posting to the forum instead of emailing the proefssor, ALL students can benefit from any assistance that is provided.

I hope this is obvious, but please be sure to NEVER post your own solutions to assignment or quiz questions. If it is impossible to ask your question without providing your code, then you should see a tutor or contact the professor.

Reach out to the Instructor: I am happy to hear from you if you have questions, if something sparks your interest, or if you are struggling with some aspect of the course. If you are struggling, I’d much rather hear from you sooner than later.

Office Hours

Please see my office hours page here.

Textbooks

The required textbook is Secret History: The Story of Cryptology, 2nd edition by Craig Bauer, which is available in hardcopy and in electronic form. Please note that you need the 2nd edition.

Changes to Syllabus

This syllabus is subject to change as necessary during the quarter. If a change occurs, it will be communicated to you via News postings.

Getting Started

This course will use two web sites.

• The first is my personal web page at: http://condor.depaul.edu/ymendels/233/

  • This page contains links to all important documents such as course notes, example web documents, this syllabus, and other resources.

• The second is DePaul University’s course management system called ‘D2L’: https://d2l.depaul.edu

  • This is where you will submit your assignments and see your grades.

  • News postings will also be available here.

Please be sure to bookmark both of these on your browser.

News Postings

After the first few days of the quarter, all communications will occur through D2L ‘News’ postings. These postings are extremely important – particularly so for online courses. So make absolutely certain that you have “subscribed” to News postings. By subscribing, all News postings will automatically be sent to your email. Information on subscribing wil be emailed to you early in the course.

READ (don't "skim") the News postings!! Some students make a habit of just skimming these postings when they come out. Please do not do this! For online-only courses in particular, they often contain important information. Course policies may be updated, deadlines change, assignments may have typos, etc. etc. So do be sure and read them!

Course Topics

Note that these are subject to change depending on timing.

College Policies

Incomplete

An incomplete grade is given only for an exceptional reason such as a death in the family, a serious illness, etc. Any such reason must be documented. Any incomplete request must be made at least two weeks before the final, and approved by the Dean of the College of Computing and Digital Media. Any consequences resulting from a poor grade for the course will not be considered as valid reasons for such a request. Incompletes are only granted when the large majority of the course work has already been completed.

Academic Policies

All students are required to manage their class schedules each term in accordance with the deadlines for enrolling and withdrawing as indicated in the University Academic Calendar. Information on enrollment, withdrawal, grading and incompletes can be found at: cdm.depaul.edu/enrollment.

Online Course Evaluations

Evaluations are a way for students to provide valuable feedback regarding their instructor and the course. Detailed feedback will enable the instructor to continuously tailor teaching methods and course content to meet the learning goals of the course and the academic needs of the students. They are a requirement of the course and are key to continue to provide you with the highest quality of teaching. The evaluations are anonymous; the instructor and administration do not track who entered what responses. A program is used to check if the student completed the evaluations, but the evaluation is completely separate from the student’s identity. Since 100% participation is our goal, students are sent periodic reminders over three weeks. Students do not receive reminders once they complete the evaluation. Students complete the evaluation online in Campus Connect.

Academic Integrity and Plagiarism

The course adheres to the DePaul University's Academic Integrity Policy. For complete information about Academic Integrity at DePaul University, please see: http://academicintegrity.depaul.edu/.

Cheating is any action that violates university norms or instructor's guidelines for the preparation and submission of assignments. This includes, but is not limited to, unauthorized access to examination materials prior to the examination itself; use or possession of unauthorized materials during the examination or quiz; having someone take an examination in one's place; copying from another student; unauthorized assistance to another student; or acceptance of such assistance. Plagiarism involves the presentation of the work of another as one's own. Plagiarism includes, but is not limited to the following: the direct copying of any source, such as written and verbal material, computer files, audio disks, video programs or musical scores, whether published or unpublished, in whole or part, without proper acknowledgment that it is someone else's; copying of any source in whole or part with only minor changes in wording or syntax, even with acknowledgment; submitting as one's own work a report, examination paper, computer file, lab report or other assignment that has been prepared by someone else (including research papers purchased from any other person or agency); the paraphrasing of another's work or ideas without proper acknowledgment; working so closely with another person so as to produce identical code.

The use of others' web/publication content (text, graphics, code) is regarded as plagiarism if credit is not given (see the above description of plagiarism). When you directly quote someone's work, you must put it in quotation marks. Without such quotations and reference, it is regarded as an act of plagiarism (see the above description of plagiarism). Using materials that the student prepared for other purposes (e.g., for another course or for his/her work) needs the course instructor's prior permission.

A charge of cheating and/or plagiarism is always a serious matter. It can result in an automatic F in the course and possible expulsion. More information can be found at http://academicintegrity.depaul.edu/. If you have any questions, consult with instructor.

Use of AI Agents such as ChatGPT

In a word: DO NOT DO THIS! It is surprisingly easy to figure out when students have done this. Every quarter, I find a number of these, though, fortunately, the frequency has come down quite a bit. However, consequences will be potentially severe. At the very least, a formal Academic Integrity violation will be filed and it will be placed in your academic record.

Penalties can range from a 0 on the assignment to an F for the entire course. (It has happened).

Again, I find this every single quarter. If you use one of these agents (or get "help" from any outside source such as a friend), there is a VERY VERY VERY good chance that it will be detected. This is plagiarism as it means that you did not come up with the code on your own, and is a violation of academic integrity.

Even if you use the agent without the intention of using the code, it's very easy for this unfamiliar code to creep into your assignments. Again, this happens every single quarter.

Please do not be one of these people! Going through the Academic Integrity process is very stressful for all involved and can lead to serious consequences in terms of your academic career.

To summarize: Do not ever use an Artificial Intelligence agent when working on your assignments. There is a very good chance that unfamiliar code will end up appearing in your assignments if you do. The penalties can be severe. Instead, put the time and effort into learning the course material. After all, this is the whole point if your being at university!!

Sharing / Posting of Course Materials

All students are expected to abide by the University’s Academic Integrity Policy which prohibits cheating and other misconduct in student coursework. Publicly sharing or posting online any prior or current materials from this course (including exam questions or answers), is considered to be providing unauthorized assistance prohibited by the policy. Both students who share/post and students who access or use such materials are considered to be cheating under the Policy and will be subject to sanctions for violations of Academic Integrity.

Students with Disabilities

**Students who feel they may need an accommodation based on the impact of a disability should contact the instructor privately to discuss their specific needs. All discussions will remain confidential. To ensure that you receive the most appropriate accommodation based on your needs, contact the instructor as early as possible in the quarter (preferably within the first week of class), and make sure that you have contacted the Center for Students with Disabilities (CSD) at: csd@depaul.edu.

Lewis Center 1420, 25 East Jackson Blvd. Phone number: (312)362-8002 Fax: (312)362-6544 TTY: (773)325.7296**

In Class Students - Classroom Decorum

Most of the following will apply primarily to in-class sections.

Attendance: For in-class sections, students are expected to attend each class and to remain for the duration. However, attendance will not be factored into your final grade.

Attitude: A professional and academic attitude is expected throughout this course. Measurable examples of non-academic or unprofessional attitude include but are not limited to: talking to others when the instructor is speaking, mocking another’s opinion, emailing, texting or using the internet whether on a phone or computer. If any issues arise a student may be asked to leave the classroom. The professor will work with the Dean of Students Office to navigate such student issues.

Civil Discourse: DePaul University is a community that thrives on open discourse that challenges students, both intellectually and personally, to be Socially Responsible Leaders. It is the expectation that all dialogue in this course is civil and respectful of the dignity of each student. Any instances of disrespect or hostility can jeopardize a student’s ability to be successful in the course. The professor will partner with the Dean of Students Office to assist in managing such issues.

Cell Phones: If you bring a cell phone to class, it must be off or set to a silent mode. Should you Out of respect to fellow students and the professor, texting is never allowable in class. If you are required to be on call as part of your job, please advise me at the start of the course.