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Corresponding entry in Aachen Campus, Bonn University (Lecture, Tutorial).

First meeting: Monday, 26 October 2009, 1300, b-it bitmax.


Prof. Joachim von zur Gathen



Konstantin Ziegler



Time & Place

No lecture on Thursday, 7 January 2010.




4+2 SWS, 8 credits. Optionally, 3+2 SWS, 6 credits.

Successful completion of the course yields 8 credit points. For students who only want 6 credit points, a breakpoint at about 3/4 of the teaching time will be defined, and only the course material up to that point will be relevant for their exams and grades. Students who wish to take the 6 credit version are required to indicate this until February 22nd by email to the tutor.




Cryptography deals with methods for secure data transfer. In earlier times this was the domain of military and intelligence agencies, but today modern cryptography has grown into a key technology, enabling e-commerce and secure internet communications. Its many applications range from credit and debit cards, mobile phones, tv decoders, and electronic money to unforgeable electronic signatures under orders and contracts in the internet. In the course, we first discuss two of the current standard tools, namely AES and RSA. Further topics are key exchange, including group cryptography and discrete logarithm, digital signatures and identification, and cryptographic hash functions.

Final Exam

The final exam took place

You were invited to join us after the exam for an "Apfelschorle" at the Bönnsch.

Results are available at b-it 1.22.

Students who took, but failed the final exam may register until March 22nd 2010 for the make-up exam 

Certificates will be available for pickup at b-it 1.26.

The lecture's mailing list

Students are encouraged to ask and answer any questions related to the course on the mailinglist:

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You can subscribe and unsubscribe to the mailing list using the information given on the list's Info page.

Establishing secure communication

Students are advised to exchange PGP keys with the tutor.

  1. Install Mozilla Thunderbird
  2. Install GnuPG
  3. Install the Thunderbird-Add-On Enigmail
  4. Call OpenPGP from the menu with the same name in Thunderbird.
  5. Follow the assistant to generate your own PGP key.
  6. Upload your PGP key to a key server using the appropriate option in the key management.
  7. Send a signed email with subject "cryptography 2009/10" and non-empty body to the tutor.
  8. Bring a fingerprint of your PGP key to the next lecture and give it to the tutor.
  9. Ask if you have questions.

Submission guidelines

Solving the exercises is crucial for a good understanding of the course's content.

You may submit your solutions either as a hardcopy or as attachment to an email.  In any case put your name in the upper right corner of the first sheet.

If your submission is handwritten,

If you submit by email, follow these steps:

  1. The subject of the email should be "assignment ## by NN" where ## is the number of the assignment and NN is your name.
  2. Your solution must consists of

    • either: a single attached, printable file, best a PDF, (you may want to look for a "pdf printer" if your OS does not natively support pdf export)

    • or: as text only in the mail body.

    A printout of this single thing must contain your name. Your solution can only be graded if the name is on the printout readably.

    (A zipped file is not printable and counts as many files!)

    Please make sure that a printout is readable!

  3. Sign the entire mail including attachments.

  4. Do not encrypt.
  5. Try to keep the size of your mail fairly below 5MB.




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