Chapter 8: Security in Computer Networks Flashcards
Which property of secure communication is described below?
Only sender & intended receiver should “understand” message contents.
1. Sender encrypts message
2. Receiver decrypts message
Confidentiality
Which property of secure communication is described below?
Sender & receiver want to confirm each other’s identity
Authentication
Which property of secure communication is described below?
Sender & receiver want to ensure message not altered, in transit / afterwards, without detection
Message integrity
Which property of secure communication is described below?
Services must be accessible & available to users
Access & availability / Operational security
What act that a “bad guy” can do, is described below?
Intercept messages, or delete or modify them
Eavesdrop
What act that a “bad guy” can do, is described below?
Putting message into connection
Insertion
What act that a “bad guy” can do, is described below?
Faking (spoofing) source address or other fields in a packet
Impersonation
What act that a “bad guy” can do, is described below?
“Taking over” ongoing connection by removing sender/receiver, and inserting themselves in their place
Hijacking
What act that a “bad guy” can do, is described below?
Preventing a service from being used by others
Denial of service
Which type of attack for breaking an encryption scheme is described below?
When the “bad guy” has a ciphertext that they can analyze
Ciphertext-only attack
Which type of attack for breaking an encryption scheme is described below?
A cipher text-only attack where the attacker search through all keys
Brute force
Which type of attack for breaking an encryption scheme is described below?
When the attacker has a plaintext corresponding to a ciphertext
Known-plaintext attack
Which type of attack for breaking an encryption scheme is described below?
When the attacker can get the ciphertext for a chosen plaintext
Chosen-plaintext attack
What is the type of cryptography where the sender and receiver share the same key, K, called?
Symmetric key cryptography
What’s this cipher called?
A cipher that substitutes one thing for another
Substitution cipher
What’s this cipher called?
A cipher that substitutes one letter for another
Monoalphabetic cipher
What is the US encryption standard with a 56-bit symmetric key, 64-bit plaintext input and block cipher with cipher block chaining called?
Data Encryption Standard (DES)
What do we call chaining where data is encrypted in specific blocks, and each block is dependent on the blocks before it for decryption?
Cipher block chaining
What do we call the symmetric key NIST standard that replaced DES, processes data in 128 bit blocks & uses 128, 192, or 256 bit keys?
Advanced Encryption Standard (AES)
What do we call the sort of cryptography where the sender & receiver don’t share a secret key, but use a public encryption key known to all & a private decryption key known only to the receiver?
Public key cryptography
If given the public key in public key cryptography, should one be able to compute the corresponding private key?
No, the fact that this should be impossible is one of the requirements for public key encryption algorithms
What do we call the cryptographic technique analogous to hand-written signatures?
Digital signatures
What attribute of digital signatures is described below?
The recipient can prove to someone that the sender & no one else must’ve signed the document
Verifiable / non-forgeable
What cryptography technique that ensures message integrity has the following goal?
Fixed-length, easy-to-compue digital “fingerprint”
Message digest
