[FY25 PKI Capability Training] Digital Signatures

What is the primary function of a digital signature?

• To verify authenticity and integrity of a message or document.

• To compress the size of a document.

• To encrypt the contents of a message.

• To format a document for printing.

Answer explanation

The primary function of a digital signature is to verify the authenticity and integrity of a message or document, ensuring that it has not been altered and confirming the identity of the sender.

Which of the following is a key component of a digital signature?

• Hash Function

• Public Key

• All of the above

• Private Key

Answer explanation

A digital signature relies on a hash function to create a unique digest of the message, a private key to sign it, and a public key to verify the signature. Therefore, all components are essential, making 'All of the above' the correct answer.

A _____ is a cryptographic algorithm that creates a unique digital fingerprint of a message.

• public key

• private key

• digital signature

• hash function

Answer explanation

A hash function is a cryptographic algorithm that generates a unique digital fingerprint of a message, ensuring data integrity. Unlike public and private keys, which are used for encryption, a hash function focuses on creating a unique representation.

Which of the following is a common digital signature algorithm?

• AES

• SHA-256

• RSA

• MD5

Answer explanation

RSA is a widely used digital signature algorithm that relies on asymmetric cryptography. In contrast, AES and SHA-256 are encryption and hashing algorithms, respectively, while MD5 is an outdated hashing algorithm.

A _____ is a mathematical technique used to verify the authenticity and integrity of a digital message or document.

• public key

• digital certificate

• private key

• digital signature

Answer explanation

A digital signature is a mathematical technique that ensures the authenticity and integrity of a digital message or document, making it the correct choice. Public and private keys are used in the process, but they do not verify authenticity directly.

The (a) is used to encrypt data, while the (b) is used to decrypt data.

• (a) Public Key

  (b) Private Key

• (a) Private Key

  (b) Public Key

Answer explanation

The Public Key is used to encrypt data, allowing anyone to secure information for the owner. The Private Key, on the other hand, is used to decrypt that data, ensuring only the owner can access it.

What is the main purpose of using a hash function in digital signatures?

• To generate a random number.

• To create a unique digital fingerprint of the message.

• To provide a timestamp.

• To encrypt the data.

Answer explanation

The main purpose of using a hash function in digital signatures is to create a unique digital fingerprint of the message. This ensures data integrity and authenticity, allowing the recipient to verify that the message has not been altered.

(a) is preventing a party from denying their involvement in a transaction or communication.

• Authorization

• Non-Repudiation

• Key Management

• Integrity

Answer explanation

Non-Repudiation ensures a party cannot deny their involvement in a transaction, while Key Management involves the generation, storage, distribution, and revocation of cryptographic keys, making both terms correct.

(a) is ensuring that data is only accessible to authorized individuals.

(b) is ensuring that data has not been modified or corrupted.

• (a) Authorization

  (b) Authentication

• (a) Authorization

  (b) Non-Repudiation

• (a) Key Management

  (b) Authentication

• (a) Confidentiality

  (b) Integrity

• (a) Authorization

  (b) Integrity

Answer explanation

(a) refers to Confidentiality, which ensures data is accessible only to authorized individuals. (b) refers to Integrity, which ensures data has not been modified or corrupted. Thus, the correct answers are Integrity and Confidentiality.

(a) is verifying the identity of a person or device.

(b) is granting access to resources based on a user's identity and permissions.

• (a) Authentication

  (b) Confidentiality

• (a) Authentication

  (b) Authorization

• (a) Authorization

  (b) Authentication

• (a) Authentication

  (b) Key Management

Answer explanation

(a) refers to Authentication, which verifies identity, while (b) refers to Authorization, which grants access based on that identity and permissions. Both are essential for secure access control.