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CISSP Exam - Question 331


Which of the following is required to verify the authenticity of a digitally signed document?

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Correct Answer: C

To verify the authenticity of a digitally signed document, the recipient must use the sender's public key. When a document is digitally signed, the sender's private key is used to create the digital signature. The recipient then uses the sender's public key to decrypt the digital signature and retrieve the original hash of the document. By computing the hash of the received document and comparing it to the decrypted hash, the recipient can confirm the document's authenticity. Therefore, the correct answer is the sender's public key.

Discussion

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RollizoOption: B
Oct 1, 2022

Rather than encrypting the data itself, you can create a one-way hash of the data and then use your private key to encrypt the hash. The encrypted hash, along with other information like the hashing algorithm, is known as a digital signature.

jackdryan
May 14, 2023

B is correct

Tygrond87Option: D
May 10, 2023

The correct answer is D. Sender's private key. To verify the authenticity of a digitally signed document, the recipient must have the sender's public key and the signed document itself. The recipient then uses the public key to decrypt the digital signature on the document, which was created using the sender's private key. The digital signature is created by encrypting a hash of the document using the sender's private key. When the recipient decrypts the signature using the sender's public key, they obtain the hash of the original document. They can then compute the hash of the received document themselves and compare it to the decrypted hash. If the two hashes match, then the document is considered authentic and has not been modified in transit.

Nickname53796Option: C
Oct 19, 2022

…verify the signature with the senders public key

Nickname53796
Oct 19, 2022

Which isn’t an option. Next best is the hash

Jamati
Nov 13, 2022

He misread the answers

HughJassoleOption: B
Jul 2, 2023

B. "The hash value is unique to the document that is hashed or encrypted and any changes in that document will lead to a changed hash value, this characteristic facilitates the validation of the data by the recipients" https://hashstudioz.com/blog/how-does-a-digital-signature-help-in-validating-a-documents-authenticity/

SoleandheelOption: C
Dec 15, 2023

B. Digital hash of the signed document The digital hash of the signed document is used in the process of verifying the authenticity of a digitally signed document. When a document is digitally signed, a hash of the document is created, and that hash is encrypted with the sender's private key to create the digital signature. To verify the authenticity of the document, the recipient uses the sender's public key to decrypt the signature and obtain the hash. Then, the recipient hashes the received document and compares it to the decrypted hash. If they match, it verifies the document's authenticity.

franbarpro
Oct 25, 2022

The "I" in CIA

BoyBastosOption: C
Sep 4, 2023

C. Recipient's public key To verify the authenticity of a digitally signed document, the recipient uses the sender's public key. The sender signs the document using their private key, and the recipient can then verify the signature using the corresponding public key. If the signature is valid, it confirms the authenticity of the document and ensures that it was indeed signed by the holder of the private key. The other options are not used for verifying the authenticity of a digitally signed document in the context of public key infrastructure (PKI).

BoyBastos
Sep 4, 2023

I stand corrected. C is recipient public key and not senders.

thanhlbOption: B
Oct 23, 2023

option C. Recipient's public key not true, people is confusing with sender's public key using to verify a digital signature, so B is my choice

klarakOption: B
May 7, 2024

The question is about authenticity so B would be correct. You need the hash to determine that.