easyMultiple Choice
SSCP Practice Question: When implementing a digital signature, which key…
When implementing a digital signature, which key is used to create the signature?
⚠ Common exam trap
It's easy for candidates to confuse the roles of keys in encryption versus signing, mistakenly thinking the receiver's private key or the sender's public key is used to create the signature because they associate 'private' with secrecy and 'public' with sharing, without understanding the specific asymmetric operations required for non-repudiation.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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Sender's private key
In a digital signature scheme, the sender uses their own private key to create the signature. This ensures non-repudiation because only the sender possesses that private key, and the corresponding public key can verify the signature. The process involves encrypting a hash of the message with the sender's private key, as specified in standards like PKCS#1 and RFC 8017.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Receiver's private key
Why it's wrong here
Signing with the receiver's private key would let anyone holding that key forge signatures, and the receiver cannot verify authorship since senders lack it. It is tempting because private keys do perform signing, but only the sender's own private key, paired with the sender's public key for verification.
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Sender's private key
Why this is correct
A digital signature is produced by encrypting a hash of the message with the sender's private key. Only the sender possesses that key, so any recipient using the corresponding public key can verify authenticity and integrity, providing non-repudiation.
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Sender's public key
Why it's wrong here
Public keys verify signatures; they cannot create them, since anyone could then forge a signature using the freely distributed key. It is tempting because the sender's key pair is genuinely involved, but the private half performs signing while the public half is published for verification.
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Receiver's public key
Why it's wrong here
The receiver's public key is unrelated to signing; it encrypts data sent to that receiver, and the sender has no access to the receiver's private key. It is tempting because public keys do feature in digital signatures, but the sender's public key is the one used, and only for verification.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SSCP exam.