CompTIA Security+ Exam: PKI Concepts for Secure Information Sharing

PKI Concepts for Secure Information Sharing

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Question

A user needs to send sensitive information to a colleague using PKI.

Which of the following concepts apply when a sender encrypts the message hash with the sender's private key? (Choose two.)

Answers

Explanations

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A. B. C. D. E.

AE.

When a sender encrypts the message hash with the sender's private key, two concepts are applied in PKI:

  1. Non-repudiation: Non-repudiation is the ability to prove that a message was sent and received by a specific sender and receiver. When the sender encrypts the message hash with their private key, they are essentially digitally signing the message. This digital signature ensures that the sender cannot later deny sending the message, as the signature can be used to prove their identity. Thus, the concept of non-repudiation is applied in PKI when a sender encrypts the message hash with their private key.

  2. Message integrity: Message integrity is the assurance that a message has not been tampered with or altered during transmission. When the sender encrypts the message hash with their private key, it acts as a checksum. If the message is tampered with during transmission, the recipient can compare the hash value they receive with the original hash value that was encrypted by the sender. If the hash values do not match, it means the message has been altered and has lost its integrity. Thus, the concept of message integrity is also applied in PKI when a sender encrypts the message hash with their private key.

Email content encryption, steganography, and transport security are not applicable in this scenario because they do not involve the use of a sender's private key to encrypt a message hash.