Study guide Flashcards
What is the Bifid Cipher?
A cipher that maps letters to numeric values and combines substitution and transposition.
What is the Playfair Cipher?
A cipher using a 5x5 matrix of letters for digraph substitution (pairs of letters).
What is the Caesar Cipher?
A cipher that shifts each letter of the plaintext by a fixed number.
What is the purpose of the Kasiski Examination?
It breaks the Vigenère/Polyalphabetic cipher.
What does XOR operation do?
XOR compares two binary values; for example: 1110 XOR 1011 = 0101.
What is the difference between symmetric and asymmetric cryptography?
Symmetric: Fast speed
Asymmetric: More secure
What are the components known to the recipient before encryption in both symmetric and asymmetric cryptography?
- Nonce
- Private Key
- Public Key
- Cryptographic Algorithm
- Plaintext
What is Privacy Enhanced Mail (PEM)?
A text-based format for certificates.
What is a True Random Number Generator (TRNG)?
A device that generates random numbers using a physical process.
Which cipher does the Clipper Chip use?
Skipjack.
What is the purpose of a digital signature?
To verify that a data entity was created by the claimed sender.
What are differential cryptanalysis, algebraic attack, and linear cryptanalysis?
Types of attacks on cryptographic algorithms.
How does key length affect performance and security?
As key length increases, performance decreases, but security improves.
What is the LM hash mechanism?
A method used to store passwords in a hashed form in Windows operating systems.
How often is a new block added to the blockchain?
Every 10 minutes.
How do mining rewards relate to blockchain length?
As blockchain length increases, mining rewards decrease.
What are the steps to send a digitally signed message using public cryptography?
- Generate a public/private key pair
- Sign the message with the private key
- Send the signed message
What are the block cipher modes of operation?
- ECB: Each block is processed separately with the same key.
- CBC: Initialization vector (IV) encrypts the first block and then encrypts subsequent blocks.
- CFB: IV is encrypted, XORed with the next block, and used as an IV for subsequent blocks.
- OFB: Block 1 is XOR’d with the encrypted IV; the output is XOR’d with the second block.
- CTR: Encrypts and XORs a counter value and nonce with the plaintext block.
What is the similarity between AES and RC4?
Both are symmetric ciphers.
What is a prime number?
A number that is divisible by 1 and itself.
What encryption standards should you know (WEP, WPA, WPA2)?
- WEP: Uses different keys for different sessions.
- WPA: Improved security over WEP.
- WPA2: Stronger security than WPA.
What are the stages of key/certificate management?
- Initialization
- Issued
- Cancellation
What is forward secrecy?
A cryptographic property where session keys are not compromised even if the server’s private key is later exposed.
What is homomorphic encryption?
Encryption that allows computations on encrypted data without revealing the plaintext.
What is the difference between WPA-Enterprise and WPA-Personal?
- WPA-Enterprise: Requires authentication using a RADIUS server.
- WPA-Personal: Uses a pre-shared key for authentication.
What is the difference between IPSec transport vs. tunnel mode?
- Transport Mode: Encrypts the payload (data).
- Tunnel Mode: Encrypts the entire packet, including the header.
What is a brute force attack?
An attack where every possible key combination is tried until the correct one is found.
What is the hash value size for SHA-1?
160 bits.
What encryption does GSM use?
A5/1 and A5/2 stream encryption.
What is OCSP used for?
Online Certificate Status Protocol is used to check the revocation status of an X.509 digital certificate.
What is the MOD function?
A mathematical operation where you divide one number by another and return the remainder (e.g., 53 mod 11 = 9).
What is NT LAN Manager (NTLM)?
An authentication protocol used in Windows. If the password is shorter than 14 characters, it is padded with null characters before encryption.
What is Chaskey?
A 128-bit hash function.
Why create a hash when collecting evidence?
To ensure data integrity by generating a unique identifier for the data.
What does PKCS #5, 7, 10, and 12 stand for?
Standards for key management and cryptographic operations, such as password-based encryption and public key certificates.
What is the recommended way to memorize the blocks and keys for cryptographic algorithms?
- Blocks: CART = 128, other = 64 (except RC5).
- Keys: CARBT = 128, 192, 256, others need to be memorized.
