Cryptography

5 minutes 5 Questions

Cryptography is a method of securing information and communication through the use of codes, making the data intelligible only to those parties who possess the decryption keys. Cryptography involves the creation, storage, and secure transfer of cryptographic keys, providing data confidentiality, integrity, authentication, and non-repudiation. Cryptographic methods are essential in ensuring the protection of sensitive information during transmission or when stored. There are two primary types of cryptography: symmetric key and asymmetric key. Symmetric key cryptography involves the usage of the same key for both encryption and decryption, whereas asymmetric key cryptography uses a public-private key pair, where one key is used to encrypt the data, and the other key is used for decryption.

Guide to Cryptography for CISSP

What is Cryptography?
Cryptography is the practice and study of techniques to secure communications in the presence of adversaries. It is a method of protecting information and communications by transforming the original representation of the information, known as plaintext, into an alternative form known as ciphertext.

Why is Cryptography Important?
Cryptography plays a vital role in information security. It provides the necessary tools for privacy, confidentiality, data integrity, non-repudiation, and authentication. Without the use of cryptography, data sent via internet can be intercepted and read by anyone.

How does Cryptography Work?
Cryptography works by using algorithms and mathematical equations to secure communications. An algorithm is used to transform plaintext into ciphertext (encryption) and then back into plaintext (decryption).

Exam Tips: Answering Questions on Cryptography
1. Understand the Basic Concepts: It is essential to have a clear understanding of basic cryptography concepts such as symmetric and asymmetric encryption, hash functions, and digital signatures.
2. Practice with Real-World Examples: Understanding how cryptography is applied in real-life scenarios can help answer exam questions.
3. Know the Algorithms: Be familiar with basic cryptographic algorithms such as DES, RSA, AES and HMAC.
4. Understand Key Management: Key management, including key exchange, storage, and the lifecycle of cryptographic keys, is often a critical part of the exam.
5. Think Like a Cryptographer: Remember that the primary goal of cryptography is to ensure data confidentiality, integrity, and authenticity. Try to understand not only how the puzzles are put together, but also why they are assembled in that way.

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Question 1

An organization is using digital signatures to ensure the integrity of their data. Recently, a security breach was discovered, and data was tampered with. Which cryptographic element was compromised or not used correctly?

Symmetric key Encryption Hashing Asymmetric key

Correct Answer: Hashing

Digital signatures rely on hashing to ensure data integrity. If data was tampered with, the hashing function or its implementation was compromised or not used correctly. Encryption and symmetric or asymmetric keys are primarily used for confidentiality, not integrity, while key distribution and key management do not directly relate to data integrity.

Question 2

A large company wants to implement a public key infrastructure (PKI). As a part of the PKI implementation, ensuring secure key storage is a top priority. What should be used to store the private keys?

Secure FTP Server Hardware Security Module (HSM) Cloud-based Key Management Service Encrypted USB Drive

Correct Answer: Hardware Security Module (HSM)

A Hardware Security Module (HSM) provides the most secure option for storing private keys, as it is purpose-built, tamper-resistant, and designed to securely manage cryptographic keys. An FTP server, cloud-based service, USB drive, file server, and database may not provide the same level of security as an HSM.

Question 3

An organization is using digital certificates to authenticate its users. A user's private key has been compromised. What should the organization do to prevent unauthorized access?

Generate a new public key Increase the certificate's expiration date Revoke the user's certificate Reissue the certificate with an increased key size

Correct Answer: Revoke the user's certificate

Revoking the user's certificate will prevent unauthorized access by making the compromised private key invalid. Generating a new public key, reissuing the certificate with an increased key size, or increasing the expiration date do not address the compromised private key. Switching to symmetric key cryptography and implementing multi-factor authentication do not solve the specific issue of the compromised private key.

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