Encryption/Decryption

Which of the following best describes the fundamental mechanism by which a digital signature ensures non-repudiation? A. The sender encrypts the entire message with their public key, and the recipient decrypts it with their private key.

• The sender encrypts the entire message with their public key, and the recipient decrypts it with their private key.

• The sender creates a hash of the message and encrypts this hash with their private key; the recipient uses the sender's public key to decrypt the hash and verifies it against their own calculated hash

• The recipient encrypts the message with the sender's public key, and the sender decrypts it with their private key.

• A trusted third party directly authenticates both the sender and recipient before communication begins.

Hashing primarily serves to encrypt data, making it unreadable to unauthorized parties, thereby ensuring confidentiality.

• True

• False

In the context of hashing functions, what is the 'Input Key'?

• The cryptographic algorithm used to convert data.

• The fixed-length string of letters and numbers produced by the hash function.

• The original data or message that is processed by the hash function.

• A data structure used for storing hash values.

MD5 is explicitly recommended as a secure hashing algorithm for new applications requiring strong cryptographic integrity, as indicated in the presentation's list of common algorithms.

• True

• False

Digital signatures find their practical application across various industries. Which of the following is NOT listed as a key application?

• Decentralized finance (DeFi)

• Healthcare records

• Supply chain management

• Real-time video conferencing encryption

Which of the following statements accurately differentiates asymmetric cryptography from symmetric cryptography in terms of key management and security services provided?

• Asymmetric cryptography uses a single shared key for both encryption and decryption, providing only confidentiality.

• Symmetric cryptography requires two distinct keys, offering confidentiality, authenticity, and non-repudiation.

• Asymmetric cryptography uses separate public and private keys, providing confidentiality, authenticity, and non-repudiation.

• Symmetric cryptography is slower for large data transfers, whereas asymmetric cryptography is faster.

One of the key challenges of asymmetric cryptography is its slow speed, making it generally less ideal for encrypting large volumes of data compared to symmetric methods.

• True

• False

In a mobile chat system utilizing both symmetric and asymmetric cryptography, what is the typical role of asymmetric cryptography at the start of a conversation?

• To encrypt the ongoing contents of the conversatio

• To verify the identity of participants.

• To generate a single shared key for bulk data encryption.

• To reduce the size of the ciphertext for faster transmission.

For symmetric key encryption, the size of the ciphertext produced is always larger than the original plaintext.

• True

• False

Which application listed in the presentation primarily uses asymmetric cryptography for confirming identity to authorize transactions, rather than for bulk data encryption?

• Banking (encrypting credit card information)

• Data storage (encrypting data on a device)

• Blockchain (confirming identity for cryptocurrency transactions)

• Mobile chat systems (encrypting ongoing conversation contents)