Dataset Viewer
id
int64 0
134
| question
stringlengths 40
1.55k
| choice
listlengths 4
7
| answer
listlengths 1
3
| label
stringclasses 5
values |
|---|---|---|---|---|
0
|
The following ciphertext was encoded via Caesar cipher with a fixed shift of three letters. Determine the original plaintext: HQFUBSWHG ZRUG.
|
[
"ABANDONED WORD",
"ENCRYPTED TEXT",
"ABANDONED TEXT",
"ENCRYPTED WORD",
"None of the above"
] |
[
3
] |
classic
|
1
|
On Encrypting "thepepsiisintherefrigerator" using Vigenère Cipher System using the keyword "HUMOR" we get cipher text.
|
[
"abqqfduugzulqtipaqfraidokvl",
"abqdvwmugzulqtipaqfraidokvl",
"abqqfsuugzukqtipaqfraidokvl",
"abqdvsuugzulqtigaqfraidokvl",
"abqdvwmuwjphfvvyyrfznydokvl"
] |
[
4
] |
classic
|
2
|
In the Triple DES encryption scheme, the total key length is ( ) and the ``meet-in-the-middle'' attack requires ( ) computational tests to breach the cipher.
|
[
"${168}$, $2^{111}$",
"${192}$, $2^{112}$",
"${184}$, $2^{111}$",
"${168}$, $2^{112}$",
"None of the above"
] |
[
3
] |
symmetric
|
3
|
Which of the following is a valid property for congruence?
|
[
"$a \\equiv b \\ (\\mathrm{mod}\\ n)$ if $n\\mid(a-b)$",
"$a \\equiv b \\ (\\mathrm{mod}\\ n)$ implies $b \\equiv a \\ (\\mathrm{mod}\\ n)$",
"$a \\equiv b \\ (\\mathrm{mod}\\ n)$ and $b \\equiv c \\ (\\mathrm{mod}\\ n)$ implies $a \\equiv c \\ (\\mathrm{mod}\\ n)$",
"All of the mentioned",
"None of the above"
] |
[
3
] |
math
|
4
|
Assuming the plaintext is guaranteed to be unique and at most one block long, which DES mode minimizes overhead?
|
[
"Cipher Block Chaining (CBC)",
"Output Feedback Modes (OFB)",
"Electronic Code Book (ECB)",
"Cipher Feedback Mode (CFB)",
"None of the above"
] |
[
2
] |
symmetric
|
5
|
Using the Linear Congruential Method (LCM) with parameters $a = 7$, $c = 0$, and $m = 32$ ($X_{n+1} \equiv (aX_n + c) \mod m$), determine the period of the generated sequence.
|
[
"11",
"4",
"13",
"7",
"None of the above"
] |
[
1
] |
symmetric
|
6
|
In the Linear Congruential Method (LCM), what is the most suitable choice for the modulus $m$ to maximize the period?
|
[
"$2^{31} - 1$",
"$2^{32}$",
"$2^{31}$",
"$2^{32} - 1$",
"None of the above"
] |
[
0
] |
symmetric
|
7
|
Find the solution of $x^2 \equiv 3 \mod 11$.
|
[
"$x \\equiv -9 \\mod 11$ and $x \\equiv 9 \\mod 11$",
"$x \\equiv 9 \\mod 11$",
"$x \\equiv 5 \\mod 11$ and $x \\equiv 6 \\mod 11$",
"No Solution",
"None of the above"
] |
[
2
] |
math
|
8
|
Let $(E, D)$ be a (one-time) semantically secure cipher with key space $K = \{0,1\}^\ell$. A bank wishes to split a decryption key $k \in \{0,1\}^\ell$ into three pieces $p_1, p_2, p_3$ so that any two of the pieces enable decryption using $k$, but no single piece can decrypt. The bank generates two random pairs $(k_1, k_1')$ and $(k_2, k_2')$ such that $k_1 \oplus k_1' = k_2 \oplus k_2' = k$. How should the bank assign pieces so that any two pieces enable decryption using $k$, but no single piece can decrypt?
|
[
"$p_1 = (k_1, k_2)$, $p_2 = (k_1', k_2')$, $p_3 = (k_2')$",
"$p_1 = (k_1, k_2)$, $p_2 = (k_2, k_2')$, $p_3 = (k_2')$",
"$p_1 = (k_1, k_2)$, $p_2 = (k_1', k_2)$, $p_3 = (k_2')$",
"$p_1 = (k_1, k_2)$, $p_2 = (k_1')$, $p_3 = (k_2')$",
"None of the above"
] |
[
2
] |
misc
|
9
|
Suppose Alice is broadcasting packets to 6 recipients $B_1, \ldots, B_6$. Privacy is not important, but integrity is. Each recipient should be assured that the packets are from Alice. Alice sets up 4 secret keys $S = \{k_1, k_2, k_3, k_4\}$. She gives each user $B_i$ a subset $S_i \subseteq S$ of the keys. When Alice transmits a packet, she appends 4 tags computed with each of her 4 keys. User $B_i$ accepts a packet as valid only if all tags corresponding to his keys in $S_i$ are valid.
How should Alice assign keys to the 6 users so that no single user can forge packets on behalf of Alice and fool some other user?
|
[
"$S_1 = \\{k_1, k_2\\}$, $S_2 = \\{k_1, k_3, k_4\\}$, $S_3 = \\{k_1, k_4\\}$, \\\\\n$S_4 = \\{k_2, k_3\\}$, $S_5 = \\{k_2, k_3, k_4\\}$, $S_6 = \\{k_3, k_4\\}$",
"$S_1 = \\{k_2, k_4\\}$, $S_2 = \\{k_2, k_3\\}$, $S_3 = \\{k_3, k_4\\}$, \\\\\n$S_4 = \\{k_1, k_3\\}$, $S_5 = \\{k_1, k_2\\}$, $S_6 = \\{k_1, k_4\\}$",
"$S_1 = \\{k_1, k_2\\}$, $S_2 = \\{k_1, k_3\\}$, $S_3 = \\{k_1, k_4\\}$, \\\\\n$S_4 = \\{k_2, k_3, k_4\\}$, $S_5 = \\{k_2, k_3\\}$, $S_6 = \\{k_3, k_4\\}$",
"$S_1 = \\{k_1, k_2\\}$, $S_2 = \\{k_1\\}$, $S_3 = \\{k_1, k_4\\}$, \\\\\n$S_4 = \\{k_2, k_3\\}$, $S_5 = \\{k_2, k_4\\}$, $S_6 = \\{k_3, k_4\\}$",
"None of the above"
] |
[
1
] |
misc
|
10
|
Suppose $H_1$ and $H_2$ are collision resistant hash functions mapping inputs in a set $M$ to $\{0,1\}^{256}$. Our goal is to show that the function $H_2(H_1(m))$ is also collision resistant. We prove the contrapositive: suppose $H_2(H_1(\cdot))$ is not collision resistant, that is, we are given $x \neq y$ such that $H_2(H_1(x)) = H_2(H_1(y))$. We build a collision for either $H_1$ or for $H_2$. This will prove that if $H_1$ and $H_2$ are collision resistant then so is $H_2(H_1(\cdot))$. Which of the following must be true
|
[
"Either $H_2(x), H_2(y)$ are a collision for $H_1$ or $x, y$ are a collision for $H_2$.",
"Either $x, H_1(y)$ are a collision for $H_2$ or $H_2(x), y$ are a collision for $H_1$.",
"Either $x, y$ are a collision for $H_1$ or $H_1(x), H_1(y)$ are a collision for $H_2$.",
"Either $x, y$ are a collision for $H_2$ or $H_1(x), H_1(y)$ are a collision for $H_1$.",
"None of the above"
] |
[
2
] |
symmetric
|
11
|
Let $(E,D)$ be a secure tweakable block cipher. Define the following MAC $(S,V)$$$S(k,m) := E(k,m,0) \quad \text{and} \quad V(k,m,\text{tag}) := \begin{cases} 1 & \text{if } E(k,m,0) = \text{tag} \\ 0 & \text{otherwise} \end{cases}$$
In other words, the message $m$ is used as the tweak, and the plaintext given to $E$ is always set to $0$. Is this MAC secure?
|
[
"It depends on the specific tweakable block cipher.",
"Yes",
"No",
"None of the above"
] |
[
1
] |
symmetric
|
12
|
Consider a key exchange protocol using an online Trusted Third Party (TTP). Suppose Alice, Bob, and Carol are three users of this system, each sharing a secret key with the TTP denoted $k_a, k_b, k_c$ respectively. They wish to generate a group session key $k_{ABC}$ that will be known to Alice, Bob, and Carol, but unknown to an eavesdropper. How would you modify a typical TTP-based protocol to accommodate this group key exchange? (Note: assume all these protocols are insecure against active attacks).
|
[
"\\begin{minipage}[t]{\\linewidth}\nAlice contacts the TTP. The TTP generates a random $k_{AB}$ and a random $k_{AC}$. The TTP sends to Alice: \\\\\n$E(k_a, k_{AB})$, $ticket_1 \\leftarrow E(k_b, k_{AB})$, $ticket_2 \\leftarrow E(k_c, k_{AC})$. \\\\\nAlice sends $ticket_1$ to Bob and $ticket_2$ to Carol.\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nAlice contacts the TTP. The TTP generates a random $k_{ABC}$ and sends to Alice: \\\\\n$E(k_a, k_{ABC})$, $ticket_1 \\leftarrow E(k_b, k_{ABC})$, $ticket_2 \\leftarrow E(k_c, k_{ABC})$. \\\\\nAlice sends $ticket_1$ to Bob and $ticket_2$ to Carol.\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nBob contacts the TTP. The TTP generates a random $k_{AB}$ and a random $k_{BC}$. The TTP sends to Bob: \\\\\n$E(k_a, k_{AB})$, $ticket_1 \\leftarrow E(k_a, k_{AB})$, $ticket_2 \\leftarrow E(k_c, k_{BC})$. \\\\\nBob sends $ticket_1$ to Alice and $ticket_2$ to Carol.\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nAlice contacts the TTP. The TTP generates a random $k_{ABC}$ and sends to Alice: \\\\\n$E(k_a, k_{ABC})$, $ticket_1 \\leftarrow k_{ABC}$, $ticket_2 \\leftarrow k_{ABC}$. \\\\\nAlice sends $ticket_1$ to Bob and $ticket_2$ to Carol.\n\\end{minipage}",
"None of the above"
] |
[
1
] |
misc
|
13
|
Suppose we modify the Diffie-Hellman protocol. Alice chooses a random $a \in \{1, \ldots, p-1\}$ and sends $A = g^a \pmod{p}$ to Bob. Bob, however, chooses a random $b \in \{1, \ldots, p-1\}$ and sends $B = g^{1/b} \pmod{p}$ to Alice (where $1/b$ denotes $b^{-1} \pmod{p-1}$, the modular multiplicative inverse of $b$ modulo $p-1$). What shared secret can they generate, and how would they do it?
|
[
"Shared secret is $g^{ab}$. Alice computes $B^{1/a} \\pmod{p}$ and Bob computes $A^b \\pmod{p}$.",
"Shared secret is $g^{a/b}$. Alice computes $B^a \\pmod{p}$ and Bob computes $A^{1/b} \\pmod{p}$.",
"Shared secret is $g^{b/a}$. Alice computes $B^a \\pmod{p}$ and Bob computes $A^{1/b} \\pmod{p}$.",
"Shared secret is $g^{a/b}$. Alice computes $B^{1/a} \\pmod{p}$ and Bob computes $A^b \\pmod{p}$.",
"None of the above"
] |
[
1
] |
asymmetric
|
14
|
Consider a toy key exchange protocol using public key encryption. Suppose that when sending his reply $c \leftarrow E(pk, x)$ to Alice, Bob appends a MAC $t:= S(x, c)$ to the ciphertext, so that what is sent to Alice is the pair $(c,t)$. Alice verifies the tag $t$ and rejects the message from Bob if the tag does not verify. Will this additional step prevent the man-in-the-middle attack described in lectures?
|
[
"Yes",
"It depends on what public key encryption system is used.",
"No",
"It depends on what MAC system is used.",
"None of the above"
] |
[
2
] |
misc
|
15
|
Suppose $n+1$ parties, denoted $B, A_1, \ldots, A_n$, wish to establish a shared group key. They require a protocol such that upon completion, all parties possess a common secret key $k$. An eavesdropper observing the entire communication must not be able to determine $k$. The parties agree on the following protocol, which operates in a group $G$ of prime order $q$ with a generator $g$ \begin{enumerate}
\item For $i=1, \ldots, n$, party $A_i$ chooses a random secret integer $a_i \in \{1, \ldots, q-1\}$ (i.e., $a_i \in \mathbb{Z}_q^*$) and sends $X_i = g^{a_i}$ to Party $B$.
\item Party $B$ generates a random secret integer $b \in \{1, \ldots, q-1\}$ (i.e., $b \in \mathbb{Z}_q^*$). For each $i=1, \ldots, n$, Party $B$ computes $Y_i = X_i^b = (g^{a_i})^b = g^{a_i b}$ and sends $Y_i$ to Party $A_i$.
\end{enumerate}
The intended shared group key is $k = g^b$. Party $B$ can compute this key directly since $B$ knows $b$. How can each Party $A_i$ (who knows $a_i$ and receives $Y_i$) compute this group key $k=g^b$?
|
[
"Party $A_i$ computes $g^b$ as $Y_i^{a_i}$.",
"Party $A_i$ computes $g^b$ as $Y_i^{1/a_i}$.",
"Party $A_i$ computes $g^b$ as $Y_i - a_i$.",
"Party $A_i$ computes $g^b$ as $(Y_i^{-1})^{1/a_i}$.",
"None of the above"
] |
[
1
] |
asymmetric
|
16
|
Recall that the standard RSA trapdoor permutation operates in the group $\mathbb{Z}_N^*$, where $N$ is the product of two large distinct primes. The public key is $(N,e)$ and the private key is $(N,d)$, where $d$ is the modular multiplicative inverse of $e$ modulo $\phi(N)$ (i.e., $e \cdot d \equiv 1 \pmod{\phi(N)}$).
Suppose, hypothetically, that RSA was defined modulo a prime $p$ instead of a composite $N$. In this modified scenario, the "public key" would be $(p,e)$. How would one compute the corresponding "private key" exponent $d$ given $(p,e)$?
|
[
"$d \\leftarrow e^{-1} \\pmod{p^2}$",
"$d \\leftarrow e^2 \\pmod{p}$",
"$d \\leftarrow e^{-1} \\pmod{p-1}$",
"$d \\leftarrow -e \\pmod{p}$",
"None of the above"
] |
[
2
] |
asymmetric
|
17
|
Let $(E, D)$ be a CPA-secure cipher defined over $(K, M, C)$ and let $H_1: M \to T$ and $H_2: C \to T$ be collision-resistant hash functions. Consider the following modified encryption schemes\medskip
\textbf{Scheme A):}
\begin{itemize}
\item Encryption: $E_1(k, m) := E(k, m) \| E(k, m)$ (concatenation of two ciphertexts)
\item Decryption: $D_1(k, c_1 \| c_2) := \begin{cases} D(k, c_1) & \text{if } D(k, c_1) = D(k, c_2) \\ \text{reject} & \text{otherwise} \end{cases}$
\end{itemize}
\medskip
\textbf{Scheme B):}
\begin{itemize}
\item Encryption: $E_2(k, m) := \text{let } c \leftarrow E(k, m); \text{ output } (c, c)$
\item Decryption: $D_2(k, (c_1, c_2)) := \begin{cases} D(k, c_1) & \text{if } c_1 = c_2 \\ \text{reject} & \text{otherwise} \end{cases}$
\end{itemize}
\medskip
\textbf{Scheme C):}
\begin{itemize}
\item Encryption: $E_3(k, m) := \text{let } c \leftarrow E(k, m); \text{ output } (c, H_1(m))$
\item Decryption: $D_3(k, (c, h)) := \begin{cases} D(k, c) & \text{if } H_1(D(k, c)) = h \\ \text{reject} & \text{otherwise} \end{cases}$
\end{itemize}
\medskip
\textbf{Scheme D):}
\begin{itemize}
\item Encryption: $E_4(k, m) := \text{let } c \leftarrow E(k, m); \text{ output } (c, H_2(c))$
\item Decryption: $D_4(k, (c, h)) := \begin{cases} D(k, c) & \text{if } H_2(c) = h \\ \text{reject} & \text{otherwise} \end{cases}$
\end{itemize}
\medskip
Which of the above schemes guarantees authenticated encryption (AE) security (Authenticated-encryption (AE) = CPA privacy + ciphertext-integrity (INT-CTXT))?
|
[
"Scheme A",
"Scheme B",
"Scheme C",
"Scheme D",
"None of the above"
] |
[
4
] |
symmetric
|
18
|
Which of the following AES modes of operation fails to provide semantic security under standard assumptions, meaning it may leak patterns from plaintext to ciphertext?
|
[
"AES in CBC mode with a random IV",
"AES in CTR mode",
"AES in ECB mode",
"AES in GCM mode",
"None of the above"
] |
[
2
] |
symmetric
|
19
|
In the idealized Random Oracle Model, which cryptographic primitive is most often analyzed as if it were a truly random function to support security proofs?
|
[
"Block ciphers",
"Public-key encryption systems",
"Cryptographic hash functions",
"Message authentication codes",
"None of the above"
] |
[
2
] |
misc
|
20
|
Which of the following values among 17, 20, 38, and 50 does \textbf{NOT} admit primitive roots in the multiplicative group $\mathbb{Z}_n^*$?
|
[
"17",
"50",
"38",
"20",
"None of the above"
] |
[
3
] |
math
|
21
|
Evaluate Euler's totient function: $\phi(25) = $
|
[
"22",
"24",
"20",
"25",
"None of the above"
] |
[
2
] |
math
|
22
|
Find an integer $x$ such that $0 \le x \le 28$ and $x^{85} \equiv 6 \pmod{35}$. Which value of $x$ satisfies the congruence?
|
[
"6",
"28",
"8",
"32",
"None of the above"
] |
[
0
] |
math
|
23
|
Which of the following is the smallest positive integer $x$ that satisfies the following system of congruences:
\begin{align*}
x &\equiv 2 \pmod{3},\
x &\equiv 5 \pmod{7},\
x &\equiv 11 \pmod{13}.\end{align*}
|
[
"16",
"54",
"89",
"121",
"None of the above"
] |
[
3
] |
math
|
24
|
Using Rabin cryptosystem with parameters $p=23$ and $q=7$, compute the ciphertext for plaintext $28$. The ciphertext is
|
[
"42",
"93",
"140",
"127",
"None of the above"
] |
[
2
] |
asymmetric
|
25
|
Within the ElGamal cryptosystem, suppose the prime $p = 31$. If $g$ is chosen as the smallest primitive root modulo $p$ and the private key $d = 10$, compute the value of $y$ such that $y \equiv g^d \bmod p$.
|
[
"24",
"36",
"25",
"62",
"None of the above"
] |
[
2
] |
asymmetric
|
26
|
Let $E(k,x)$ be a secure block cipher. Consider the following tweakable block cipher construction$$E'((k_1,k_2), t, x) = E(k_1, x) \oplus E(k_2, t)$$
where $(k_1, k_2)$ is the key, $t$ is the tweak, and $x$ is the plaintext block. Is this tweakable block cipher secure?
|
[
"Yes, it is secure assuming $E$ is a secure block cipher.",
"\\begin{minipage}[t]{\\linewidth}\nNo because for $x \\neq x'$ we have \\\\\n$E'((k_1,k_2), 0, x) \\oplus E'((k_1,k_2), 0, x) = E'((k_1,k_2), 0, x') \\oplus E'((k_1,k_2), 0, x')$\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nNo because for $t \\neq t'$ we have \\\\\n$E'((k_1,k_2), t, 0) \\oplus E'((k_1,k_2), t, 1) = E'((k_1,k_2), t', 0) \\oplus E'((k_1,k_2), t', 1)$\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nNo because for $t \\neq t'$ we have \\\\\n$E'((k_1,k_2), t, 0) \\oplus E'((k_1,k_2), t', 1) = E'((k_1,k_2), t', 1) \\oplus E'((k_1,k_2), t', 0)$\n\\end{minipage}",
"\\begin{minipage}[t]{\\linewidth}\nNo because for $x \\neq x'$ and $t \\neq t'$ we have \\\\\n$E'((k_1,k_2), t, x) \\oplus E'((k_1,k_2), t', x) = E'((k_1,k_2), t, x') \\oplus E'((k_1,k_2), t', x)$\n\\end{minipage}",
"None of the above"
] |
[
2
] |
symmetric
|
27
|
Given a superincreasing sequence $l=\{38, 20, 9, 4, 2, 1\}$ (The sequence is from right to left, corresponding to the bits from low to high.) that sums to 23, determine the binary vector $n$ which yields this total.
|
[
"011111",
"010011",
"010111",
"010010",
"None of the above"
] |
[
1
] |
asymmetric
|
28
|
For RSA with $p = 11$, $q = 17$, and public exponent $e = 7$, decrypt the ciphertext 44 to recover the plaintext.
|
[
"88",
"22",
"13",
"41",
"None of the above"
] |
[
1
] |
asymmetric
|
29
|
Consider a knapsack cryptosystem where letters A-Z are mapped to integers 0 through 25. You receive ciphertext values 14, 25, and 89. If the public key is \{57, 14, 3, 24, 8\} (The sequence is from right to left, corresponding to the bits from low to high.), what plaintext corresponds to this message?
|
[
"INK",
"TIN",
"KIN",
"INT",
"None of the above"
] |
[
3
] |
asymmetric
|
30
|
How many real versus imaginary roots (when $y=0$) exist for the elliptic curve equation $y^2 = x^3 - 4x$?
|
[
"All solutions are imaginary",
"All roots are real",
"Two real, one imaginary root",
"One real, two imaginary roots",
"None of the above"
] |
[
1
] |
math
|
31
|
Let $P = (4, 3.464)$ be a point on the elliptic curve $y^2 = x^3 - 17x + 16$ over the real numbers. What is the result of computing $2P$ on this curve?
|
[
"(11.694, -43.723)",
"(12.022, -39.362)",
"(43.022, 39.362)",
"(32.022, 42.249)",
"None of the above"
] |
[
1
] |
asymmetric
|
32
|
Bob chooses the elliptic curve $E_{67}(2, 3)$ defined over $GF(67)$, along with the base point $e_1 = (2, 22)$ and a private scalar $d = 4$. He computes $e_2 = d \cdot e_1$ and publishes $(E, e_1, e_2)$. If Alice wishes to send $P = (24, 26)$ and randomly selects $r = 2$, what are the resulting ciphertext points $C_1$ and $C_2$? ($E_p(a, b) : y^2 = x^3 + ax+b \mod p$)
|
[
"C1=(35,1) ; C2 =(21,44)",
"C1=(44,21) ; C2 =(1,35)",
"C1=(44,21) ; C2 =(44,21)",
"C1=(21,44); C2 =(35,1)",
"None of the above"
] |
[
0
] |
asymmetric
|
33
|
Which of the following best characterizes the mathematical relationship between inputs and outputs in a standard MAC algorithm, considering multiple inputs can lead to the same authentication tag?
|
[
"injective (one-to-one) mapping",
"many-to-one transformation",
"surjective (onto) mapping",
"None of the above"
] |
[
1
] |
misc
|
34
|
Given a MAC algorithm with a key of size $k$ bits and an authentication tag of $n$ bits, what is the expected computational effort required for a brute-force attack that attempts to guess either the key or a valid tag?
|
[
"$2^k$",
"$2^n$",
"$\\min(2^k,\\ 2^n)$",
"$\\frac{2^k}{2^n}$",
"None of the above"
] |
[
2
] |
misc
|
35
|
What is the estimated number of operations required to generate a collision for a hashing algorithm $\mathbf{H}: \{0, 1\}^* \rightarrow \{0, 1\}^n$ ?
|
[
"$\\mathcal{O}(2^{n/2})$",
"$\\mathcal{O}(2^n)$",
"$\\mathcal{O}(2^{2n})$",
"$\\mathcal{O}(2^{n-1})$",
"None of the above"
] |
[
0
] |
symmetric
|
36
|
In the elliptic curve group defined by $y^2 = x^3 - 17x + 16$ over real numbers, what is $P + Q$ if $P = (0, -4)$ and $Q = (1, 0)$?
|
[
"(15, -56)",
"(-23, -43)",
"(69, 26)",
"(12, -86)",
"None of the above"
] |
[
0
] |
asymmetric
|
37
|
The security of the RSA encryption scheme primarily corresponds to which of the following computationally hard problems?
|
[
"The discrete logarithm problem",
"The problem of factoring large composite integers",
"Elliptic curve point addition and multiplication",
"A hybrid of factoring and discrete logarithm problems"
] |
[
1
] |
asymmetric
|
38
|
In the context of cryptographic algorithms, what best describes the avalanche effect?
|
[
"A minor change in the plaintext causes a significant change in the ciphertext",
"Changing both the key and the plaintext simultaneously leads to encryption failure",
"Changing the key slightly will force a completely different plaintext",
"A slight change in the ciphertext affects the decryption key",
"None of the above"
] |
[
0
] |
misc
|
39
|
Which of the following is a correct difference between CBC (Cipher Block Chaining) mode and Counter (CTR) mode encryption?
|
[
"CBC mode requires padding for partial blocks, whereas CTR mode does not.",
"CTR mode is inherently sequential and cannot be parallelized, whereas CBC can.",
"CBC mode allows random access decryption, whereas CTR mode does not.",
"In CBC mode, encryption can be parallelized, whereas decryption cannot in CTR mode.",
"None of the above"
] |
[
0
] |
symmetric
|
40
|
Why is it important to use a random Initialization Vector (IV) in CBC mode encryption?
|
[
"A random IV prevents leakage of message patterns across different encryptions.",
"A random IV ensures resistance against chosen plaintext attacks in block cipher ECB mode.",
"A random IV allows decryption without knowing the key.",
"A random IV ensures integrity protection of the ciphertext.",
"None of the above"
] |
[
0
] |
symmetric
|
41
|
When implementing CBC-MAC, which type of IV should be used and why?
|
[
"A fixed IV, to guarantee deterministic and repeatable MAC outputs.",
"No IV is required for CBC-MAC.",
"A random IV, to ensure non-determinism in message authentication.",
"A unique IV per message, to prevent replay attacks.",
"None of the above"
] |
[
0
] |
symmetric
|
42
|
Given an RSA public key $(N,e)$ and the factorization $N = pq$, how can the secret key $d$ be computed?
|
[
"$d = e^{-1} \\mod \\varphi(N)$, where $\\varphi(N) = (p - 1)(q - 1)$",
"$d = e^{-1} \\mod (N - 1)$",
"$d = ep \\mod (q - 1)$",
"$d = p^{-1} \\mod q$",
"None of the above"
] |
[
0
] |
asymmetric
|
43
|
Which of the following best defines a collision-resistant hash function?
|
[
"It is hard to find any two distinct inputs $x \\neq x'$ such that $H(x) = H(x')$",
"Given $x$, it is hard to find $y$ such that $H(x) = H(y)$.",
"No collisions exist for any practical input set.",
"It is hard to invert the hash output.",
"None of the above"
] |
[
0
] |
symmetric
|
44
|
If a hash function $H$ is one-way, must it also be collision-resistant?
|
[
"No, a function can be one-way yet still allow finding collisions efficiently.",
"Yes, one-wayness always implies collision resistance.",
"Yes, since inverting implies finding collisions.",
"It depends on whether the output length $n$ is large enough.",
"None of the above"
] |
[
0
] |
symmetric
|
45
|
Let p be a prime such that $p \equiv 2 \pmod{3}$, and let $\alpha \in \mathbb{Z}_p^*$. Which of the following efficiently computes the cube root of $\alpha\pmod{p}$?
|
[
"Compute $\\alpha^{\\frac{2p-1}{3}} \\pmod{p}$.",
"Compute $\\alpha^{\\frac{p+1}{3}} \\pmod{p}$.",
"Compute $\\alpha^{\\frac{p-1}{2}} \\pmod{p}$.",
"Cube roots modulo such primes cannot be efficiently computed.",
"None of the above"
] |
[
0
] |
math
|
46
|
What is the performance advantage of using a modulus $N' = p'q'r'$ (product of three equal-sized primes) over $N = pq$ in RSA ($\lfloor\log_2(N)\rceil = \lfloor\log_2(N')\rceil$), when employing the Chinese Remainder Theorem (CRT) for decryption?
|
[
"CRT does not apply to $N'$.",
"Decryption is faster due to smaller moduli and exponents.",
"Decryption is slower due to more primes involved.",
"Encryption becomes faster, but decryption remains the same.",
"None of the above"
] |
[
1
] |
asymmetric
|
47
|
Sender $S$ digitally signs a message $m$ using its private key and sends it to receiver $R$. Considering possible cryptographic attacks, who among the following can potentially launch a birthday attack to alter $m$ while maintaining the same hash value?
|
[
"Only S",
"Only a third-party attacker",
"S and a third-party attacker",
"Receiver R and a third-party attacker",
"None of the above"
] |
[
0
] |
misc
|
48
|
Using a columnar transposition cipher, the plaintext 'the tomato is a plant in the nightshade family' is encrypted using the keyword 'TOMATO'. What is the resulting ciphertext, grouped by columns?
|
[
"\"TINESAX / EOAHTFX / HTLTHEY / MAILAIX / TAPNGDL / OSTNHMX\"",
"\"TINESAX / EOAHTEX / MAILAIX / HTLTHEY / TAPNGDL / OSTNHMX\"",
"\"TINESAX / EOAHTFX / HTLTHEY / MAILAIX / OSTNHMX / TAPNGDL\"",
"\"EOAHTFX / TINESAX / HTLTHEY / MAILAIX / TAPNGDL / OSTNHMX\"",
"\"TINESAX / EOAHTFX / HTLTHEY / MAIIAIX / TAPNGDL / OSTNHMX\""
] |
[
4
] |
classic
|
49
|
Which of the following security properties is not inherently guaranteed by a digital signature mechanism?
|
[
"Authentication",
"Non-repudiation",
"Confidentiality",
"Integrity",
"None of the above"
] |
[
2
] |
asymmetric
|
50
|
In a public-key cryptographic scheme, if user A wants to send a secure message to user B, which key should A use to encrypt the message?
|
[
"A's private key",
"B's private key",
"B's public key",
"A's public key",
"None of the above"
] |
[
2
] |
asymmetric
|
51
|
When comparing AES with DES, which operation in DES lacks a corresponding component in AES?
|
[
"Function f",
"Permutation P",
"Swapping of left and right halves",
"XOR between subkey and function output",
"None of the above"
] |
[
2
] |
symmetric
|
52
|
In elliptic curve cryptography (ECC), the problem of "given P, a point on the curve, and the scalar multiplication Q = kP (where k is an integer), find k" primarily corresponds to which mathematical problem
|
[
"Integer factorization problem",
"Discrete logarithm problem",
"Elliptic curve discrete logarithm problem",
"Subset sum problem"
] |
[
2
] |
asymmetric
|
53
|
Imagine you are designing a secure voting system where votes need to be encrypted to ensure privacy. Which encryption scheme is most suitable for tallying votes without decrypting them all (assuming only two candidates: A and B, with encrypted votes represented as 0 or 1)?
|
[
"AES-GCM",
"RSA",
"Fully Homomorphic Encryption",
"ElGamal",
"None of the above"
] |
[
2
] |
misc
|
54
|
Suppose you have encrypted a message using RSA, where the public key is $(n, e)$ and the private key is $d$. If an attacker successfully factors the modulus n into two distinct prime numbers $p$ and $q$, what can the attacker now do?
|
[
"Decrypt any message encrypted with the public key without calculating $d$.",
"Compute the private key $d$, and thus decrypt any message encrypted with the public key.",
"Forge messages signed with the private key but cannot decrypt ciphertext.",
"Perform no meaningful attack since the encryption process remains secure.",
"None of the above"
] |
[
1
] |
asymmetric
|
55
|
What is a primary vulnerability of the Electronic Code Book (ECB) mode of encryption?
|
[
"It needs a larger block size to be secure",
"It uses excessive padding for all input sizes",
"It is susceptible to cryptanalysis due to the one-to-one mapping between plaintext and ciphertext blocks",
"None of the above"
] |
[
2
] |
symmetric
|
56
|
In a digital signature system, which key should the sender (e.g., Alice) use to sign a message so that the recipient (e.g., Bob) can verify the origin and authenticity of the message?
|
[
"Bob's private key",
"Alice's private key",
"Bob's public key",
"Alice's username and password",
"None of the above"
] |
[
1
] |
asymmetric
|
57
|
Based on the information available to an attacker, cryptanalysis attacks can generally be classified into four types: ciphertext-only attacks, known-plaintext attacks, chosen-plaintext attacks, and chosen-ciphertext attacks. Which type of attack is considered the most difficult for the attacker to attack successfully?
|
[
"Ciphertext-only attack",
"Known-plaintext attack",
"Chosen-plaintext attack",
"Chosen-ciphertext attack",
"None of the above"
] |
[
0
] |
misc
|
58
|
In the RSA blind signature scheme, how does the requester blind the original message before sending it to the signer?
|
[
"Encrypting the message with a private key",
"Encrypting a random blinding factor with the public key of RSA, and multiplying it with the message",
"Encrypting the message with a public key",
"Reordering blocks of the message",
"None of the above"
] |
[
1
] |
asymmetric
|
59
|
Which transformation step in the AES encryption algorithm is primarily responsible for achieving diffusion?
|
[
"ShiftRows",
"SubBytes",
"AddRoundKey",
"MixColumns",
"None of the above"
] |
[
3
] |
symmetric
|
60
|
Which of the following statements about confusion in cryptography is incorrect?
|
[
"Confusion aims to make the ciphertext-key relationship more complex",
"S-boxes play a key role in achieving confusion",
"Confusion can be effectively achieved using a basic XOR operation",
"The purpose of confusion is to prevent attackers from deducing the key",
"None of the above"
] |
[
2
] |
symmetric
|
61
|
If a cryptographic algorithm employs confusion but lacks diffusion, which type of attack is it most vulnerable to?
|
[
"Differential cryptanalysis",
"Linear cryptanalysis",
"Brute force attack",
"None of the above"
] |
[
0
] |
symmetric
|
62
|
What is the main objective of diffusion in the design of a secure encryption system?
|
[
"Making small changes in the plaintext significantly affect the ciphertext",
"Reducing the number of encryption rounds",
"Enhancing the non-linearity between ciphertext and key",
"Improving encryption speed",
"None of the above"
] |
[
0
] |
symmetric
|
63
|
Let $(Gen, E, D)$ be a chosen ciphertext secure public-key encryption system with message space $\{0,1\}^{128}$. Which of the following is also chosen ciphertext secure?
|
[
"$(Gen, E', D')$ where $E'(pk, m) = (E(pk, m), E(pk, 0^{128}))$ and $D'(sk, (c_1, c_2)) = D(sk, c_1)$.",
"$(Gen, E', D')$ where $E'(pk, m) = (E(pk, m), E(pk, m))$ and \\\\\n$D'(sk, (c_1, c_2)) = \\begin{cases} D(sk, c_1) & \\text{if } D(sk, c_1) = D(sk, c_2) \\\\ \\perp & \\text{otherwise} \\end{cases}$.",
"$(Gen, E', D')$ where $E'(pk, m) = E(pk, m \\oplus 1^{128})$ and $D'(sk, c) = D(sk, c) \\oplus 1^{128}$.",
"None of the above"
] |
[
2
] |
asymmetric
|
64
|
The letter frequency analysis method is most effective against which type of classical cipher algorithm?
|
[
"Transposition cipher",
"Monoalphabetic substitution cipher",
"Polyalphabetic substitution cipher",
"Stream cipher",
"None of the above"
] |
[
1
] |
classic
|
65
|
Which of the following cipher algorithms offers the strongest resistance to frequency analysis but the weakest resistance to known-plaintext attacks?
|
[
"Affine cipher",
"Vigenère cipher",
"Rotational cipher",
"Hill cipher",
"None of the above"
] |
[
3
] |
classic
|
66
|
The index of coincidence method is particularly effective for breaking which type of cipher?
|
[
"Transposition cipher",
"Polyalphabetic substitution cipher",
"Stream cipher",
"None of the above"
] |
[
1
] |
classic
|
67
|
The Vigenère cipher, a representative example of classical cipher systems, employs which type of encryption approach?
|
[
"Transposition cipher",
"Monoalphabetic substitution cipher",
"Polyalphabetic substitution cipher",
"Stream cipher",
"None of the above"
] |
[
2
] |
classic
|
68
|
In the DES algorithm, if all the subkeys generated from a given initial key k are identical, such a key is called a weak key. How many weak keys exist in DES?
|
[
"2",
"4",
"8",
"16",
"None of the above"
] |
[
1
] |
symmetric
|
69
|
The Index Calculus method is used to analyze which type of cryptographic algorithm?
|
[
"Knapsack cryptosystem",
"RSA",
"ElGamal",
"ECC",
"None of the above"
] |
[
2
] |
asymmetric
|
70
|
Suppose an affine cipher uses the encryption rule \( c \equiv 17m + 2 \pmod{26} \). Which of the following represents the correct decryption function?
|
[
"\\( m \\equiv 3c + 6 \\pmod{26} \\)",
"\\( m \\equiv 3c - 2 \\pmod{26} \\)",
"\\( m \\equiv 23c + 6 \\pmod{26} \\)",
"\\( m \\equiv 23c - 2 \\pmod{26} \\)",
"None of the above"
] |
[
2
] |
symmetric
|
71
|
Consider a maximum-length sequence (m-sequence) generated by an n-stage linear feedback shift register (LFSR). In one full period of this sequence, how many runs of consecutive 1s with length exactly n-1 occur?
|
[
"0",
"1",
"2",
"n",
"None of the above"
] |
[
2
] |
symmetric
|
72
|
The (t, n)-threshold scheme proposed by Shamir is based on which of the following?
|
[
"Lagrange interpolation polynomial",
"Discrete logarithm problem",
"Knapsack problem",
"Large integer factorization problem",
"None of the above"
] |
[
0
] |
misc
|
73
|
Which of the following statements about digital signatures is correct?
|
[
"A digital signature appends a piece of irrelevant digital information to the transmitted data",
"A digital signature solves the problem of secure data transmission by encryption",
"A digital signature typically uses symmetric encryption mechanisms",
"A digital signature can solve security issues such as tampering and forgery",
"None of the above"
] |
[
3
] |
asymmetric
|
74
|
What additional property transforms a commutative ring into a mathematical field?
|
[
"Existence of reciprocals for all non-null elements",
"Presence of opposites for all elements",
"Availability of reciprocals for all elements",
"Partial availability of reciprocals",
"None of the above"
] |
[
0
] |
math
|
75
|
In the AES algorithm, which component introduces non-linearity?
|
[
"Byte substitution",
"Row shifting",
"Column mixing",
"Round key addition",
"None of the above"
] |
[
0
] |
symmetric
|
76
|
For the affine cipher $y \equiv (a\cdot x + b) \mod 26$, what constraint applies to the coefficient 'a'?
|
[
"Any integer value is acceptable",
"Must be divisible by 2",
"Must be relatively prime to 26",
"Must be divisible by 13",
"None of the above"
] |
[
2
] |
symmetric
|
77
|
What correctly describes key management in public-key systems?
|
[
"All cryptographic keys are public",
"Encryption keys are public while decryption keys are private",
"Private keys are exchanged between parties",
"Both encryption and decryption keys remain secret",
"None of the above"
] |
[
1
] |
asymmetric
|
78
|
Given two distinct primes \( p \) and \( q \), let \( n = p \cdot q \). What is the value of Euler's totient function \( \varphi(n) \)?
|
[
"\\( p + q - 1 \\)",
"\\( p \\cdot q \\)",
"\\( (p - 1)(q - 1) \\)",
"\\( (p + 1)(q + 1) \\)",
"None of the above"
] |
[
2
] |
math
|
79
|
What algebraic structure do residue classes modulo a prime p form?
|
[
"A non-field ring",
"An additive group only",
"A finite field",
"An infinite field",
"None of the above"
] |
[
2
] |
math
|
80
|
In public key cryptography, what is the correct sequence for signing-then-encrypting a message?
|
[
"Sign with X's private key → Encrypt with Y's public key",
"Sign with Y's public key → Encrypt with X's private key",
"Encrypt with X's public key → Sign with Y's private key",
"Encrypt with Y's private key → Sign with X's public key",
"None of the above"
] |
[
0
] |
asymmetric
|
81
|
The Euclidean Algorithm produces a sequence $X_1 > X_2 > \ldots > X_k = 0$ of positive integers where each $X_t$ for $2 < t \leq k$ is the remainder obtained by dividing $X_{t-2}$ by $X_{t-1}$. If $X_{k-1} = 45$, then the set of all positive common divisors of $X_1$ and $X_2$ is
|
[
"{1, 3, 5, 9, 15, 45}",
"{1, 3, 5, 15}",
"{1, 3, 5}",
"{1, 9, 15, 45}",
"{1, 3, 5, 9, 15}",
"None of the above"
] |
[
0
] |
math
|
82
|
Let $L$ be the least common multiple of 175 and 105. Among all common divisors $x > 1$ of 175 and 105, let $D$ be the smallest. Which of the following is correct?
|
[
"$D = 5$ and $L = 1050$",
"$D = 7$ and $L = 1050$",
"$D = 5$ and $L = 525$",
"$D = 7$ and $L = 525$",
"$D = 5$ and $L = 35$",
"None of the above"
] |
[
2
] |
math
|
83
|
The Euclidean Algorithm is used to produce a sequence \( X_1 > X_2 > X_3 > X_4 > X_5 = 0 \) of positive integers where \( X_t = q_{t+1}X_{t+1} + X_{t+2} \), for \( t = 1, 2, 3 \). The quotients are \( q_2 = 3 \), \( q_3 = 2 \), and \( q_4 = 2 \). Which of the following is correct?
|
[
"gcd(\\( X_1, X_2 \\)) = \\( -2X_1 + 6X_2 \\)",
"gcd(\\( X_1, X_2 \\)) = \\( -2X_1 - 6X_2 \\)",
"gcd(\\( X_1, X_2 \\)) = \\( -2X_1 - 7X_2 \\)",
"gcd(\\( X_1, X_2 \\)) = \\( 2X_1 + 7X_2 \\)",
"gcd(\\( X_1, X_2 \\)) = \\( -2X_1 + 7X_2 \\)",
"None of the above"
] |
[
4
] |
math
|
84
|
Which cipher mode should always be used when available to ensure both confidentiality and integrity?
|
[
"ECB",
"CBC",
"GCM or CCM",
"CTR",
"None of the above"
] |
[
2
] |
symmetric
|
85
|
In RSA encryption, what must be enabled to protect against Known Plaintext Attacks?
|
[
"Random Padding (OAEP)",
"Initialization Vector (IV)",
"Key Derivation Function (KDF)",
"None of the above"
] |
[
0
] |
asymmetric
|
86
|
How many distinct solutions exist for the congruence equation \( x^2 \equiv 1 \mod 30 \)?
|
[
"1",
"2",
"4",
"8",
"None of the above"
] |
[
2
] |
math
|
87
|
Which of the following quotient rings does NOT define a field isomorphic to \( \text{GF}(2^5) \)?
|
[
"$GF(2)[x] / \\langle x^5 + x^4 + x^3 + x + 1 \\rangle$",
"$ GF(2)[x] / \\langle x^5 + x^3 + 1 \\rangle$",
"$GF(2)[x] / \\langle x^5 + x^4 + x^3 + x^2 + 1 \\rangle$",
"$GF(2)[x] / \\langle x^5 + x^4 + 1 \\rangle$",
"None of the above"
] |
[
3
] |
math
|
88
|
Which of the following irreducible polynomials over \( \text{GF}(3) \) is also primitive?
|
[
"\\( x^3 + 2x + 1 \\)",
"\\( x^3 + 2x + 2 \\)",
"\\( x^3 + x^2 + 2 \\)",
"\\( x^3 + x^2 + x + 2 \\)",
"None of the above"
] |
[
0
] |
math
|
89
|
In a Feistel network cipher, each round consists of \( L_i = R_{i-1} \), and which of the following describes \( R_i \)?
|
[
"\\( R_i = L_{i-1} \\oplus f(L_{i-1}, k_i) \\)",
"\\( R_i = L_{i-1} \\oplus f(R_{i-1}, k_i) \\)",
"\\( R_i = R_{i-1} \\oplus f(R_{i-1}, k_i) \\)",
"\\( R_i = R_{i-1} \\oplus f(L_{i-1}, k_i) \\)",
"None of the above"
] |
[
1
] |
symmetric
|
90
|
The block cipher IDEA uses a combination of algebraic operations from three distinct groups. Which of the following is \textbf{NOT} one of them?
|
[
"\\( (\\{0,1\\}^{16}, \\oplus) \\)",
"\\( \\mathbb{Z}_{65536}, + \\mod 65536 \\)",
"\\( S_{16}, \\circ \\text{ (composition)} \\)",
"\\( \\mathbb{Z}_{65537}^*, \\times \\mod 65537 \\)",
"None of the above"
] |
[
2
] |
symmetric
|
91
|
Let \( m_i \) and \( c_i \) denote plaintext and ciphertext blocks in CBC mode. For \( i > 1 \), what is the correct decryption operation?
|
[
"\\( m_i = d_k(c_i) \\oplus m_{i-1} \\)",
"\\( m_i = d_k(c_i \\oplus m_{i-1}) \\)",
"\\( m_i = d_k(c_i) \\oplus c_{i-1} \\)",
"\\( m_i = d_k(c_i \\oplus c_{i-1}) \\)",
"None of the above"
] |
[
2
] |
symmetric
|
92
|
The block cipher SAFER uses an 8-bit substitution defined as \( S(x) = 45^x \mod 257 \), with 256 represented by 0. Which function below is NOT a bijective mapping on 8-bit values?
|
[
"\\( S(x) = 45^{5x} \\mod 257 \\)",
"\\( S(x) = 45^{6x} \\mod 257 \\)",
"\\( S(x) = 45^{9x} \\mod 257 \\)",
"\\( S(x) = 45^{15x} \\mod 257 \\)",
"None of the above"
] |
[
1
] |
symmetric
|
93
|
In a hybrid cryptosystem, what is the role of the symmetric key?
|
[
"It is used to encrypt the public key",
"It is used to encrypt the session data after it is established",
"It is used to encrypt the private key",
"It is used for the authentication of the message sender",
"None of the above"
] |
[
1
] |
misc
|
94
|
For which prime numbers $p$ and $q$ can a cyclic multiplicative subgroup of order $q$ be constructed within $(\mathbb{Z}_p^*, \times)$? Cryptographic schemes based on the discrete logarithm problem typically operate on such groups.
|
[
"$p = 859$, $q = 103$",
"$p = 853$, $q = 101$",
"$p = 857$, $q = 107$",
"$p = 863$, $q = 109$",
"None of the above"
] |
[
2
] |
asymmetric
|
95
|
Consider a key management scheme devised by an administrator. The administrator generates an RSA modulus $N$ and a master secret $s \in \mathbb{Z}_N^*$. For each user $i$, a secret key $s_i = s^{r_i} \pmod{N}$ is assigned, where $r_i$ is the $i$-th prime number (e.g., $r_1=2, r_2=3, \ldots$).
To encrypt a file intended for a group of users, say users $i, j,$ and $t$, the administrator uses the key $k = s^{r_i r_j r_t} \pmod{N}$. Each authorized user can compute $k$. For instance, user $i$ computes $k = (s_i)^{r_j r_t} = (s^{r_i})^{r_j r_t} = s^{r_i r_j r_t} \pmod{N}$. The scheme aims to ensure that only the designated users can compute $k$ and access the file.
However, this system is insecure. Any two colluding users can combine their secret keys to recover the master secret $s$. Consider users 1 and 2, with secret keys $s_1 = s^{r_1} \pmod{N}$ and $s_2 = s^{r_2} \pmod{N}$ respectively. Since $r_1$ and $r_2$ are distinct primes, by the Extended Euclidean Algorithm (Bezout's identity), there exist integers $a$ and $b$ such that $a \cdot r_1 + b \cdot r_2 = 1$.
How can users 1 and 2 compute the master secret $s$ using their keys $s_1, s_2$ and the integers $a, b$? {}
|
[
"$s = s_1^b \\cdot s_2^a \\pmod{N}$",
"$s = s_1^a + s_2^b \\pmod{N}$",
"$s = s_1^b + s_2^a \\pmod{N}$",
"$s = s_1^a \\cdot s_2^b \\pmod{N}$",
"None of the above"
] |
[
3
] |
asymmetric
|
96
|
Which of the following is \textbf{not} a property provided by Message Authentication Codes (MACs)?
|
[
"Integrity — detecting any modification of a message during transmission",
"Authentication — verifying the message origin for the receiver",
"Non-repudiation — preventing the sender from denying message origin",
"Fixed output length — generating authentication tags of a consistent size",
"None of the above"
] |
[
2
] |
misc
|
97
|
Which of the following statements about the Digital Signature Algorithm (DSA) is \textbf{false}?
|
[
"Proposed by NIST as a US federal digital signature standard",
"Signature verification is faster than RSA at equivalent security levels",
"Based on the ElGamal signature scheme",
"Vulnerable if the same ephemeral key is reused across signatures",
"None of the above"
] |
[
1
] |
asymmetric
|
98
|
Which of the following statements about key establishment using a Key Distribution Center (KDC) is \textbf{false}?
|
[
"Each user shares a Key Encryption Key (KEK) with both the KDC and every other user",
"Only $n$ long-term keys are needed in a network with $n$ users",
"When a new user joins, only one secure key is required between the user and the KDC",
"The KDC distributes session keys encrypted under users' KEKs",
"None of the above"
] |
[
0
] |
misc
|
99
|
Which of the following quotient rings is isomorphic to the finite field $\mathbb{GF}(81)$?
|
[
"$\\mathbb{GF}_3[x] / \\langle x^4 + x + 2 \\rangle$",
"$\\mathbb{GF}_3[x] / \\langle x^4 + 2x + 1 \\rangle$",
"$\\mathbb{GF}_3[x] / \\langle x^4 + 1 \\rangle$",
"$\\mathbb{GF}_3[x] / \\langle x^4 + 2 \\rangle$",
"None of the above"
] |
[
0
] |
math
|
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