Section 2.8 Basics of Cryptographic concepts Flashcards
What do you call the conversion of machine-readable and human-readable communicated information into an unreadable form that keeps the information confidential and private?
Cryptography
The central function of cryptography is _________, the transformation of data into an unreadable form.
Encryption
Encryption ensures _______ by keeping the information hidden from those for whom the information is not intended.
Confidentiality
What transforms encrypted data back into an intelligible form?
Decryption
Cryptography also supports ________ by making systems better able to handle resource constraints.
High resiliency
Cryptographic algorithms and techniques are chosen based on?
The level of protection required and resource constraints
The number of bits that are within an encryption algorithm’s key is?
Key length/size
The set of all possible permutations of a key is the?
Keyspace
Data integrity is maintained by using what cryptologic function?
Hashing
What is often used to create signatures for files that indicate whether a file has been tampered with?
Hashing
What cryptologic function is used to maintain Authentication?
Encrypted digital certificates are used to identify users electronically on a network
By implementing _____________ processes, a cryptographic system can be considered secure for business and legal transactions?
Nonrepudiation
What concept provides security by modifying the data to make it unreadable to a human or program trying to use it?
Obfuscation
A system that provides encryption and decryption services is called a?
Cryptosystem
A cryptosystem uses a mathematical encryption ___________ to turn data into ciphertext?
Algorithm/Cipher
A _______ is like a password that’s combined with an algorithm to create the ciphertext.
key
The strength of an encryption key depends on the algorithm’s what?
keyspace
Most attacks on encryption center on what?
The interception of keys
What concept means that the outcome of the ciphertext is dependent on several parts of the key, rather than only one? This concept increases the change in the plaintext to ciphertext.
Confusion
What concept means that even a small change in the plaintext results in a significant change in the ciphertext?
Diffusion
What type of cipher switches out the plaintext characters with other characters?
Substitution Cipher
What type of cipher rearranges the characters in different places through mathematical formulas?
Transposition Cipher
What encryption scheme has both parties using the same key to encrypt and decrypt?
Symmetric Encryption/Secret Key
The security of Symmetric Encryption depends on?
Users keeping their keys private
A symmetric systems is much faster than asymmetric encryption because what?
The underlying algorithms are simpler and more efficient.
What type of symmetric encryption encrypts data one bit at a time?
Stream Ciphers
What is the most commonly found streaming cipher, found in the Wired Equivalent Privacy (WEP) protocol?
RC4
What type of symmetric encryption encrypts entire blocks of data?
Block Ciphers
What do you call authentication schemes that have been developed to work with block ciphers to provide not only encryption but also authentication?
Authenticated models of operation/Authenticated encryption
What encryption scheme uses 2 mathematically-related, different keys to encrypt and decrypt?
Asymmetric Encryption scheme
What encryption concept involves a 3rd party, such as a government agency or an authorized organization, that holds a special third key used to encrypt the private key, which is then stored in a secure location?
Key escrow
The advantage of an asymmetric scheme over symmetric schemes is that it offers a level of?
Authentication and Nonrepudiation
What kind of cryptosystem uses complex mathematical structures to create secure asymmetric algorithms and keys? Often used as a lightweight solution, provides functionality such as encryption an digital signatures.
Elliptic-curve Cryptography (ECC)
What kind of key exchange takes places within the normal communication channel?
In-band key exchange
what kind of key exchange utilizes a separate channel outside the norm to authenticate the user?
Out-of-band Key exchange
What do you call temporary keys that are made each time a key is needed and are temporary in nature?
Ephemeral Keys
What is designed by using complex cryptographic protocols to prevent the situation where a compromise of one secret key or message leads to a compromise of previous confidential messages?
Perfect Forward Secrecy (PFS)
What do you call a randomly generated input often used in hashing?
Salt
What do you call a one-time use number that are randomly created to ensure if the same message is encrypted twice then the outcomes are different?
Initialization Vector (IV)
What do you call numbers that are used once for a limited time?
Nonces
What are the difference between nonces and IV’s?
IV’s are random
What do you call the process of taking a weak key and making it stronger against attacks by creating an enhanced key; an initial key and hash function or block cipher applied in a loop?
Key stretching
What kind of cryptography uses light waves pulsing over fiber optic cable to transmit code which shares the key between two users?
Quantum Cryptography
What kind of encryption encrypts data while it is being processed? It also allows for computation to take place on ciphertext, with a result that matches what the value of the plaintext would have been if not encrypted.
Homomorphic Encryption
What concept refers to algorithms, generally asymmetric, that are considered secure against attacks using quantum computing?
Post-Quantum Computing
What is the concept of hiding data in other media such as graphic images, digital audio, or video files?
Steganography
What do you call publicly accessible ledgers that record online transactons?
Blockchains
What prevent messages from being modified in transit?
Hashing algorithms
What do you call a mathematical function that takes a variable-sized message and transforms it into a fixed-length value? Difficult to reverse and the results are never decrypted.
One-way Hash
What do you call the output of a one-way hash?
Hash Value/Message Digest
Attacks against one-way hash functions can be prevented by using?
longer hash values
What occurs when 2 different hash messages result in the same hashing value?
Hash value collisions
What attack occurs when an attacker intercepts a hash and uses it to authenticate directly, rather than using the underlying plaintext password?
Pass the Hash Attack
What is created when the digest of the message is encrypted using the sender’s private key?
Digital signature
What hash produces a 128-bit hash value used for security applications and integrity checking?
MD5
What do you call a key agreement protocol that enables users to exchange encryption keys over an insecure medium?
Diffie-Hellman Exchange (DHE)
What key agreements allow the two parties to authenticate each other through the addition of more advanced technologies and is used in the Public Key Infrastructure?
Elliptic-curve Diffie-Hellman Exchange (ECDHE)
What asymmetric algorithm is used for both digital signatures and general encryption? Widely used in open standards and cryptosystems, including PGP and GPG.
ElGamal
What is the digital authentication standard of the US Government?
Digital Signature Algorithm (DSA)
What do you call an encrypted hash value used to ensure the identity and integrity of a message?
Digital signature
What guarantees the individual sending the message is who he claims to be?
Digital signature
What is the hash function message digest originally based on MD4?
RIPEMD
What is used as an algorithm for message authentication purposes, where the authentication is applied using hash functions and a secret key to create an authentication code value?
Hash-based Message Authentication Code (HMAC)
Information assurance through encryption protects information and information systems by securing their what?
Confidentiality, integrity, authentication, and nonrepudiation
Random numbers are often used within algorithms to prevent?
Replay attacks
What do you call a small, fast key that is used for encryption in small mobile devices?
ECC
What is a feature of specific key agreement protocols that assures session keys will not be compromised if long-term secrets (private keys) used in session key exchange are compromised?
PFS
What indicates that a cryptographic system generates random public keys for each session and it does not use a deterministic algorithm in the process?
PFS
What encryption algorithm is typically used for bulk encryption/encrypting large amounts of data?
Symmetric
What kind of encryption algorithm is AES256?
Symmetric
What encryption algorithm is typically used for the distribution of symmetric bulk encryption keys (shared keys)?
Asymmetric
What encryption algorithm is typically used for identity authentication via digital signatures and certificates?
Asymmetric
What encryption algorithm is typically used for non-repudiation services and key agreements?
Asymmetric
What are typically used for the verification of digital signatures?
Hash functions
What are typically used for the generation of pseudo-random numbers?
Hash functions
What do you call the practice of harnessing the principles of quantum mechanics to improve security and detect whether a third party is eavesdropping on communications?
Quantum Cryptography
What mode of operation for block ciphers is the simplest and least secure mode? Processes 64-bit blocks, encrypts blocks with the chosen key.
Electronic Codebook Mode (ECB)
What mode of operation for block ciphers has each block of unencrypted text XORed with the block of ciphertext immediately preceding?
Cipher Block Chaining (CBC)
What mode of operation for block ciphers uses an incrementing counter instead of a seed? Errors do not propagate.
Counter (CTR)
What is the go to option for encryption for low power small devices?
ECC (Asymmetric)
What is the go to option for encryption for the military?
AES 256 (Symmetric)
What kind of encryption allows users to run calculations on data while it is still encrypted?
Homomorphic Encryption
What kind of encryption allows data to be encrypted and out-sourced to commercial clouds for processing?
Homomorphic Encryption
Low power devices often use _________ for encryption, as it uses a small key.
ECC
What should be used to check/support file integrity?
File Hash
What can be used to ensure integrity for email?
Digital signatures
