Which method provides message integrity, sender identity authentication, and non-repudiation?

Which method provides message integrity, sender identity authentication, and non-repudiation?

• A. Symmetric cryptography
• B. Message hashing
• C. Message authentication code
• D. Public key infrastructure (PKI)

Answer: (D)

The correct choice is Public Key Infrastructure (PKI), which is designed to provide a framework for secure communications and enables three critical security services: message integrity, sender identity authentication, and non-repudiation. Public Key Infrastructure utilizes asymmetric cryptography, which involves a pair of cryptographic keys: a public key, known to everyone, and a private key, kept secret by the owner. When a sender uses their private key to sign a message, it allows the recipient to verify the sender's legitimacy using the public key, thus ensuring sender identity authentication. Additionally, the act of signing the message creates a digital signature that guarantees message integrity, as any alteration of the message after signing would invalidate this signature. Furthermore, non-repudiation is achieved because the sender cannot deny having signed the message, given that the signature can be independently verified by anyone who has access to the sender's public key. This is crucial in legal and business contexts, where the accountability of communications is important. In contrast, symmetric cryptography primarily ensures confidentiality and relies on a shared secret, but it does not naturally provide non-repudiation since anyone with the key can impersonate the sender. Message hashing provides integrity by generating a fixed-size hash from the input data,

The correct choice is Public Key Infrastructure (PKI), which is designed to provide a framework for secure communications and enables three critical security services: message integrity, sender identity authentication, and non-repudiation.

Public Key Infrastructure utilizes asymmetric cryptography, which involves a pair of cryptographic keys: a public key, known to everyone, and a private key, kept secret by the owner. When a sender uses their private key to sign a message, it allows the recipient to verify the sender's legitimacy using the public key, thus ensuring sender identity authentication. Additionally, the act of signing the message creates a digital signature that guarantees message integrity, as any alteration of the message after signing would invalidate this signature.

Furthermore, non-repudiation is achieved because the sender cannot deny having signed the message, given that the signature can be independently verified by anyone who has access to the sender's public key. This is crucial in legal and business contexts, where the accountability of communications is important.

In contrast, symmetric cryptography primarily ensures confidentiality and relies on a shared secret, but it does not naturally provide non-repudiation since anyone with the key can impersonate the sender. Message hashing provides integrity by generating a fixed-size hash from the input data,