Question 4 (a)

Digital signature: definition, creation and verification

8 marks

Time to write
About 16 minutes

From an older CBCS paper

Question

Question 4 (a) · 8 marks

Define digital signature. Describe the steps by which a digital signature is created and verified: its creation and verification.

Reworded from the university paper; the task is the same. The original paper belongs to the University of Delhi. See DU's question bank.

Before you write

Read off the question and its marks

16 minfor 8 marks

Read from the question

  • Define…Describe…Two asks in one question: answer both.

What the paper leaves open

This older-course question examines the Information Technology Act, 2000, which the current UGCF Business Laws syllabus does not name; it is answered as printed.

Write it in this order

  1. Read; underline the asks; jot your points 1 min
  2. 1 Definition 2 marks 2 min
  3. 2 Steps in creation 3 marks 6 min
  4. 3 Steps in verification 3 marks 6 min
  5. Check: every ask answered, key terms underlined 1 min

Easy marks

  • Definition (step 1, 2 marks): a clear definition and a line on what it covers. It opens the answer, so it takes a minute or two.

Short on time? Keep step 1 short. Trim steps 2 and 3 evenly rather than skip one: each is capped at its own marks.

Try it first. About 16 minutes for 8 marks. Write it out, then open the solution.

Solution

Hover or tap a marked figure, like 72,000, to see how it is made and where else it appears.

Definition. Under section 2(1)(p) of the Information Technology Act, 2000, a “digital signature means authentication of any electronic record by a subscriber by means of an electronic method or procedure in accordance with” section 3.

Steps in creation:

  1. A subscriber may authenticate an electronic record by affixing his digital signature (section 3(1)).
  2. The authentication is effected by the use of an asymmetric crypto system and a “hash function, which envelop and transform the initial electronic record into another electronic record” (section 3(2)).
  3. The hash function computes the hash result of the record; the same record always yields the same result, and the record cannot feasibly be reconstructed from it.
  4. The subscriber's private key, the key of his key pair used for creating a digital signature, is applied to produce the signature, which is attached to the record.

Steps in verification:

  1. The recipient uses the subscriber's public key, the key of the pair used to verify a digital signature, which is listed in his Digital Signature Certificate.
  2. Verification determines whether “the initial electronic record was affixed with the digital signature by the use of” the private key corresponding to the subscriber's public key, and whether the record has been retained intact or altered since it was signed (section 2(1)(zh)).

Where the 8 marks sit

#ComponentMarks
1Definition2
2Steps in creation3
3Steps in verification3
Total8
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