ITPEC FE Morning October 2023 Question 38
When information, such as an e-mail or a document file, is sent and received with a digital signature via the Internet, which of the following is an appropriate combination of security properties that ensure that such information is from the signer and has not been altered or tampered with during transmission?
Explanation
Authenticity and integrity — a digital signature proves who signed the information and that it has not changed since.
The sender signs a hash of the message with his private key. The receiver verifies the signature with the sender's public key and compares it with a fresh hash of what arrived. A valid signature shows the signer's key was used (authenticity), and a matching hash shows no bit was altered (integrity).
Answer (b)
Why not others:
- •(a) Atomicity and consistency — ACID properties of database transactions, not security properties
- •(c) Availability and confidentiality — a signature neither keeps the message secret, which needs encryption, nor keeps a service running
- •(d) Durability and isolation — the other two ACID transaction properties
Key rule: A signature gives authenticity, integrity and non-repudiation; confidentiality needs encryption as well.
Security · AI-written, may contain errors
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