Chapter 7 PKI and Cryptographic Applications Flashcards
disadvantage—the algorithm doubles the length of any message it encrypts.
El Gamal
SHA-1 produces a ____-bit message digest.
and processes a message in ___-bit blocks.
160 , 512
SHA-256 produces a ___-bit message digest using a ___-bit block size.
256, 512
SHA-224 uses a truncated version of the SHA-256 hash to produce a __-bit message digest using a ___-bit block size.
224, 512
SHA-512 produces a ___-bit message digest using a ____-bit block size.
512, 1024
SHA-384 uses a truncated version of the SHA-512 hash to produce a ___-bit digest
using a ____-bit block size.
384 , 1024
MD2 pads the message so that its length is a multiple of __ bytes
16
MD2 generates a ___-bit message.
128
______ computes a 16-byte checksum and appends it to the end of the message.
MD2
__ pads the message to ensure that the message length is 64 bits smaller than a multiple of 512 bits.
MD4 , MD5
MD4 algorithm then processes ___-bit blocks of the message in three rounds of computation. The final output is a ____-bit message digest.
512, 128
Difference between MD4 and MD5 is that MD4 uses 3 rounds MD5 uses rounds.
true
Digital Signature Standard consists of which encryption algorithms ?
The Digital Signature Algorithm (DSA)
The Rivest, Shamir, Adleman (RSA)
The Elliptic Curve DSA (ECDSA)
Steganographic algorithms work by making alterations to the _____ significant bits of the many bits that make up image files.
least
protects entire communications circuits by creating a secure tunnel between two points using either a hardware solution or a software solution that encrypts all traffic entering one end of the tunnel and decrypts all traffic entering the other end of the tunnel.
End-to-end encryption
Link encryption
Link encryption
does not encrypt the header, trailer, address, and routing data, so it moves faster from point to point but is more susceptible to sniffers and eavesdroppers.
End-to-end encryption
Link encryption
End-to-end encryption
IPsec relies on security associations, and
there are two main components:
The Authentication Header (AH
The Encapsulating Security Payload (ESP)
IPsec provides for two discrete modes of operation _____ and _________
transport mode and tunnel mode
_____ mode , the entire packet, including the header, is encrypted.
tunnel mode
only the packet payload is encrypted.
transport mode
When encryption happens at the higher OSI layers, it is usually ______ encryption,
end-to-end
if encryption is done at the lower layers of the OSI model, it is usually ____ encryption
link
The attacker responds to the originator’s initialization requests and sets up a
secure session with the originator. The attacker then establishes a second secure session with the
intended recipient using a different key and posing as the originator.
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Man in the Middle
the attacker uses a known plaintext message. The
plain text is then encrypted using every possible key (k1), and the equivalent ciphertext is decrypted using all possible keys (k2). When a match is found, the corresponding pair (k1,
k2) represents both portions of the double encryption
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Meet in the Middle
the attacker has the ability to encrypt plaintext messages of their choosing and can then analyze the ciphertext output of the encryption algorithm.
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Chosen Plaintext
the attacker has the ability to decrypt chosen portions of the ciphertext message and use the decrypted portion of the message to discover the key.
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Chosen Ciphertext
the attacker has a copy of the encrypted message along with the plaintext message used to generate the ciphertext
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Known Plaintext
counting the number of times each letter appears in the ciphertext.
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Frequency Analysis and the Ciphertext Only Attack
attempts every possible valid combination for a key or password. They involve using massive amounts of processing power to methodically guess the key used to secure cryptographic
communications
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Brute Force
attempt to find a vulnerability in the hardware or operating system hosting the cryptography application
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Statistical Attack
focuses on exploiting the software code, not just errors and flaws but the methodology employed to program the encryption system.Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Implementation Attack
algebraic manipulation that attempts to reduce the complexity of the algorithm and focuses on the logic of the algorithm itself
Analytic Attack
Implementation Attack
Statistical Attack
Brute Force
Frequency Analysis and the Ciphertext Only Attack
Known Plaintext
Chosen Ciphertext
Chosen Plaintext
Meet in the Middle
Man in the Middle
Replay
Analytic Attack
Keys used within public key systems must be ____ than those used in private key systems to produce cryptosystems of equivalent strengths
longer
Which algorithm has these steps:
- Choose two large prime numbers (approximately 200 digits each), labeled p and q.
- Compute the product of those two numbers: n = p * q.
RSA public key algorithm
Name asymmetrical algorithms ( 3 )
Elliptic Curve
El Gamal
RSA
According to RSA Security, there are five basic requirements for a cryptographic hash function:
The input can be of any length.
The output has a fixed length.
The hash function is relatively easy to compute for any input.
The hash function is one-way (meaning that it is extremely hard to determine the
input when provided with the output). One-way functions and their usefulness in
cryptography are described in Chapter 6.
The hash function is collision free (meaning that it is extremely hard to find two
messages that produce the same hash value).
Which algorithm pads the message with
additional data until the length reaches the next highest multiple of 512.
SHA
If Alice wants to digitally sign a message she’s sending to Bob,
Alice then encrypts only the message digest using ______
her private key
If Alice wants to digitally sign a message she’s sending to Bob,
Bob decrypts the digital signature using ____ _______ .
Alice’s public key
S/MIME uses the ____- encryption algorithm
RSA
S/MIME relies on the use of __ for exchanging cryptographic keys.
X.509 certs
