28 Questions
What is another name for Asymmetric key encryption?
Public Key Encryption
In Asymmetric key encryption, who is the public encryption key known to?
Known to all
What is the purpose of Bob’s private key in the RSA algorithm?
To decrypt ciphertext
Why is it important to agree on a key in asymmetric key encryption?
To prevent others from knowing the entire key scheme
What is the significance of choosing large prime numbers in RSA algorithm?
To ensure security and complexity of the encryption
What is the role of Diffie-Hellman in asymmetric key encryption?
To propose the radically different approach of public and private keys
What is the main topic of Lecture 9 in the COMP1806 Information Security course?
Symmetric key encryption
Which of the following is NOT a requirement for the secure use of symmetric encryption?
Sharing the key openly with all parties
Why does symmetric key encryption fail to achieve message authentication?
Failure to keep the secret key known only to sender / receiver
What is the estimated time required to guess the correct key for AES 256?
1.8x10^56 years
What is the main focus of today's lecture on information security?
Fixing the limitations of symmetric key encryption using asymmetric key encryption
What is the key factor that often fails in achieving secure use of symmetric encryption?
Inability to ensure the secret key is ONLY known to sender and receiver
What is the main goal of cryptography?
Ensuring data confidentiality, data integrity, and data authenticity
What does integrity ensure in the context of cryptography?
The message received is the same as the message sent
How is authenticity accomplished in cryptography?
Using digital certificates
What is the meaning of concealing a message by encoding it?
The sender encrypts the message using a cryptographic key
Which technique only protects against unintentional alteration of the message in cryptography?
Using hashing to create a unique message digest
Who can prove their identity to another without personal knowledge of their identity in cryptography?
A user or system using digital certificates
What is the main focus of symmetric key cryptography?
Efficient encryption and decryption
What is the main goal of a computationally secure encryption scheme?
To make it difficult to estimate the effort required to break the cipher
In symmetric encryption, what is the relationship between plaintext length and ciphertext length?
Ciphertext is typically shorter than plaintext
What is the purpose of the encryption function EK(P) in symmetric encryption?
To perform a one-one mapping from plaintext to ciphertext
What characteristic should the encryption and decryption functions have in symmetric encryption?
They should have efficient algorithms
What is the main issue that symmetric encryption aims to address?
Secure communication over insecure channels
What is the main goal of a computationally secure encryption scheme?
To make it difficult to estimate the effort required to break the cipher
In symmetric encryption, what is the relationship between plaintext length and ciphertext length?
Ciphertext is typically shorter than plaintext
What is the main goal of an efficient symmetric encryption scheme?
To ensure that breaking the cipher is economically feasible
What characteristic should the encryption and decryption functions have in symmetric encryption?
They should have efficient algorithms
Study Notes
Asymmetric Key Encryption
- Also known as public-key encryption
- Public encryption key is known to everyone
- Purpose of Bob's private key in RSA algorithm is to decrypt the message
Key Agreement
- Important to agree on a key in asymmetric key encryption to ensure secure communication
- Diffie-Hellman is a key exchange protocol used in asymmetric key encryption
RSA Algorithm
- Choosing large prime numbers is significant in RSA algorithm to ensure security
- Large prime numbers make it difficult to factorize the modulus, thus ensuring security
Symmetric Key Encryption
- Main focus is on confidentiality and speed
- In symmetric key encryption, the key factor that often fails is key management
- Symmetric key encryption fails to achieve message authentication because it only provides confidentiality
- Estimated time required to guess the correct key for AES 256 is virtually impossible
Cryptography
- Main goal is to provide confidentiality, integrity, and authenticity
- Integrity ensures that the message is not modified or altered during transmission
- Authenticity is accomplished through digital signatures
- Concealing a message by encoding it is called encryption
- Digital signatures only protect against unintentional alteration of the message
Identity Verification
- Zero-knowledge proof allows one to prove their identity to another without revealing their identity
Symmetric Encryption Scheme
- Main goal is to provide confidentiality and ensure that the encryption scheme is computationally secure
- Relationship between plaintext length and ciphertext length is that the ciphertext length is equal to or greater than the plaintext length
- Purpose of the encryption function EK(P) is to map plaintext to ciphertext
- Encryption and decryption functions should be invertible and efficiently computable
- Main issue that symmetric encryption aims to address is confidential transmission of data
- Main goal of an efficient symmetric encryption scheme is to provide fast encryption and decryption
Test your knowledge on applications of cryptography in information security with a focus on threat actors, risk assessment, security for machine learning, designing secure systems, and more. This quiz covers the concepts discussed in Lecture 9 of the COMP1806 course.
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