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Questions and Answers
What term is used to describe the process of converting plaintext to ciphertext?
What is a block cipher?
What type of crypto system is used when both the sender and receiver utilize the same key?
Which of the following cryptographic algorithms uses 64-bit blocks and is a symmetric encryption method?
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What is the key size utilized by a DES system?
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What is a significant disadvantage of symmetric encryption systems?
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Which statement is most accurate regarding newly developed encryption methods?
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Certified encryption methods are best described as:
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What will be the value of Phi if using the RSA algorithm with prime numbers p = 5 and q = 11?
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In asymmetric encryption, which key does Carol use to encrypt a message intended for Bob?
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What key will Bob use to decrypt the message once Carol has encrypted it for confidentiality?
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How many private and public keys are used in a classroom of 30 students and a professor if every student submits an encrypted assignment?
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Why is public-key encryption generally considered more secure than symmetric encryption?
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The RSA algorithm is primarily used in which of the following applications?
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The effectiveness of the Diffie-Hellman algorithm relies on what mathematical concept?
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What is the most widely used public-key cryptosystem?
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In an asymmetric cryptography system, who uses the private key to decrypt ciphertext?
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What type of document does a Certification Authority issue to bind a subscriber's name to a public key?
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The primary objective of a hash function is to ensure what?
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Which family of cryptographic hash functions is the most widely used?
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In the context of digital signatures, the hash value of a message is encrypted with which key?
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What guarantees does a digital signature provide?
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When comparing hash values to verify a message's integrity, what indicates that the message has not been altered?
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What key does a sender use to digitally sign a hash before sending it?
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Study Notes
Encryption and Decryption
- Deciphering/Decryption: The process of converting ciphertext back to plaintext.
- Symmetric Key Cryptosystem: Uses the same key for both encryption and decryption.
Symmetric Key Encryption
- Block Cipher: Encrypts data in blocks, often 8 or 16 bits, transforming each block with a key.
- DES (Data Encryption Standard): A classic symmetric cryptosystem using 64-bit blocks with a 56-bit key.
- Disadvantage of Symmetric Encryption: The difficulty of securely transmitting the secret key.
Choosing Encryption Methods
- Consider the vendor's claims carefully: Don't assume advertised "unbreakable" methods are truly reliable.
- New Encryption Methods: Use with caution until they have been thoroughly tested and proven.
- Certified Encryption Methods: Check the level and source of certification to ensure they are trustworthy.
Asymmetric Key Encryption
- Public-Key Cryptosystem: Uses two keys: a public key for encryption and a private key for decryption.
- RSA: The most widely used public-key cryptosystem.
- Diffie-Hellman Algorithm: Dependent on the difficulty of computing discrete logarithms for its security.
- RSA Modulus (N): Calculated by multiplying two large prime numbers (p and q). Finding the prime numbers from N is virtually impossible.
- Confidentiality with Asymmetric Encryption: The sender (Carol) uses the receiver's (Bob's) public key to encrypt messages.
- Decryption with Asymmetric Encryption: The receiver (Bob) uses their private key to decrypt the message.
Digital Signatures
- Public Key Cryptosystem for Digital Signatures: The sender uses their private key to sign the hash of the message before sending it.
- Hash Function's Purpose: Ensures data integrity and authentication.
- Purpose of a Digital Certificate: Authenticates the public key.
- Verification of Digital Signatures: Upon receiving a message, the receiver compares the hash value of the message to the original hash value in the digital signature.
- Equal Hash Values: Indicate that the message has not been altered.
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Description
Test your knowledge on encryption and decryption techniques, including symmetric and asymmetric key systems. This quiz covers important concepts like block ciphers, DES, and the selection of encryption methods. Understand the advantages and disadvantages of various encryption techniques.
