*:48 Electronic mail

Exam 13 January 1996 with full score answers

Last update 10 Oct 1996 by Jacob Palme <jpalme@dsv.su.se>.

Allowed books during the exam: Ordinary language dictionaries to and from Swedish and English.

Read carefully the questions and check that you answer the right question. In one exam, one question was "Describe some properties of non-simultaneous computer conferencing systems, which are different from electronic mail systems". One student gave a very comprehensive description of the differences between computer conferencing and face-to-face meetings. Such a reply will unfortunately give no points at all!


The introduction of electronic mail in a company is sometimes successful, sometimes not. Discuss various factors which can increase the probability of success.

Full score answer:

  • Ensure that you get a large enough critical mass of users,
  • Ensure that the supervisors support the introduction of e-mail,
  • Ensure that important people in the company participate,
  • The users must have need and will to communicate,
  • Each user must personally find that the advantages are larger than the disadvantages,
  • Plan the introduction well, give necessary courses for key personnel, etc.

Compare quality, efficiency, benefits and usefulness of electronic mail as compared to ordinary telephone calls.

Full score answer:

If you want to reach one person, the work time on an average phone call of 4,5 minutes duration is about the same as for four e-mail messages. Thus, e-mail is less costly than phone calls for simple matters which do not require many messages. E-mail is also almost always less costly than phone calls if you want to reach more than one person. However, phone calls or face-to-face meetings have been found to be more productive if you want to negotiate or discuss complex matters.



What is meant by digital authentication, signature and seal, and why is open-key encryption useful for these services?

Full score answer:

By authentication is meant identification of who is using a service, by digital signature is meant identification of who sent a message, by digital seal is meant safeguarding that a message has not been modified in transmission. All three services often use open key encryption, because no exchange of secret keys is then necessary between the involved parties. Open key encryption can be used getting the holder of a secret key to encrypt a random number and check that the correct result is returned, or for seals, by encrypting a checksum of the document with the secret key. Any holder of the open key can check that the identification, signature or seal is valid.


What is meant by ASN.1 and why is ASN.1 used in standards?

Full score answer:

ASN.1, short for Abstract Syntax Notation One, is a language for specifying the data structures exchanged through computer networks. ASN.1 allows the specification of complex structures with good readability. More than one encoding rule can be used for the same specified structure.