(a) Digital security infrastructure

(b) Food security infrastructure

(c) Health care and education infrastructure

(d) Telecommunication and transportation infrastructure  

Ans: d

Explanation:

Public key infrastructure (PKI) is a comprehensive framework for assigning, identifying and verifying user identity through digital certificates used for enabling trustworthy and secure digital communications.

Paired with public-key cryptography, digital certificates act as virtual passports—authenticating the identity and permissions of various users and entities when establishing secure end-to-end communication over public or private networks. Encompassing elements of software, hardware, policies and procedures, PKI formalizes the process to create, distribute, manage and revoke digital certificates.

Public key infrastructure (PKI) provides protocols to validate the authenticity of the digital certificates that underscore the trust in public key cryptography systems. A cornerstone of cybersecurity, cryptography provides confidentiality, integrity, nonrepudiation and authenticity. PKI adds validity to cryptographic systems by cryptographically binding digital certificates to unique users, institutions, entities and third parties.

The ability to establish the secure transfer of information between users, entities and devices enables ecommerce and banking platforms to collect financial information, allows Internet of Things (IoT) connected devices and establishes confidential lines of communication, for secure email web servers, cybersecurity specialists rely on data encryption to securely encrypt (scramble) and decrypt (unscramble) sensitive data.

The two primary types of data encryption are known as public key cryptography and private key cryptography.

What is public key cryptography?

Also known as asymmetric encryption or public key encryption, public key cryptography uses a pair of keys, a shared public key and a private key that is unique to each party. The public key is used for encryption while the private key is used for decryption.

What is private key cryptography?

Also known as symmetrical or secret key cryptography, private key cryptosystems use only one key for both encryption and decryption. 

Cryptography is also used for common messaging applications like email and WhatsApp to provide end-to-end encryption (E2EE) and maintain the privacy of users’ conversations. With E2EE, only the sender and intended recipient can decrypt and read their messages, making it nearly impossible for third parties—including users’ own service providers—to access the content.

While symmetric cryptography is faster, asymmetric cryptography is often more practical and secure. In practice, both types of cryptosystems are often used together.

However, both types of systems can be vulnerable to so-called man-in-the-middle (MitM) attacks, in which a malicious eavesdropper might intercept secure data during transmission.

Hence, option d is correct.

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