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EC-Council 212-81 Exam - Topic 5 Question 67 Discussion

Posted by Mitsue on Mar 05, 2026 at 06:47 PM

An attack that is particularly successful against block ciphers based on substitution-permutation networks. For a block size b, holds b-k bits constant and runs the other k through all 2k possibilities. For k=1, this is just deferential cryptanalysis, but with k>1 it is a new technique.

Suggested Answer: D

Integral Cryptanalysis

https://en.wikipedia.org/wiki/Integral_cryptanalysis

Integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based on substitution-permutation networks. It was originally designed by Lars Knudsen as a dedicated attack against Square, so it is commonly known as the Square attack. It was also extended to a few other ciphers related to Square: CRYPTON, Rijndael, and SHARK. Stefan Lucks generalized the attack to what he called a saturation attack and used it to attack Twofish, which is not at all similar to Square, having a radically different Feistel network structure. Forms of integral cryptanalysis have since been applied to a variety of ciphers, including Hierocrypt, IDEA, Camellia, Skipjack, MISTY1, MISTY2, SAFER++, KHAZAD, and FOX (now called IDEA NXT).

Incorrect answers:

Chosen Plaintext Attack - is an attack model for cryptanalysis which presumes that the attacker can obtain the ciphertexts for arbitrary plaintexts. The goal of the attack is to gain information that reduces the security of the encryption scheme.

Linear Cryptanalysis - is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers. Linear cryptanalysis is one of the two most widely used attacks on block ciphers.

Differential Cryptanalysis - is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how differences in information input can affect the resultant difference at the output. In the case of a block cipher, it refers to a set of techniques for tracing differences through the network of transformation, discovering where the cipher exhibits non-random behavior, and exploiting such properties to recover the secret key (cryptography key).


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26 comments · newest first
PA
Paz 2 months ago
I agree with A) Differential Cryptanalysis. The constant bits part is key to the definition.
EA
Earlean 2 months ago
I'm leaning towards D) Integral Cryptanalysis. It sounds like a new approach to me.
LU
Lura 2 months ago
I feel like it's B) Linear Cryptanalysis. The k>1 part makes me think of linear techniques.
IR
Ira 2 months ago
I think it's A) Differential Cryptanalysis. It fits the description well.
RO
Rolland 2 months ago
C) Chosen Plaintext Attack seems off. It doesn’t match the technique described.
BE
Beata 3 months ago
I feel A is definitely the best choice. The k>1 part is key.
FR
Frederic 3 months ago
I agree, but what about B) Linear Cryptanalysis? It also targets block ciphers.
JU
Julio 3 months ago
I think it's A) Differential Cryptanalysis. It fits the description well.
AL
Allene 3 months ago
A) Differential Cryptanalysis seems right. It matches the k=1 explanation perfectly.
ME
Melodie 3 months ago
I'm leaning towards D) Integral Cryptanalysis. It sounds like a new technique.
EL
Eladia 4 months ago
I feel like it's B) Linear Cryptanalysis. The constant bits make sense.
TH
Thaddeus 4 months ago
I think it's A) Differential Cryptanalysis. It fits the description well.
FR
Francine 4 months ago
I disagree, it’s not integral cryptanalysis either.
TR
Truman 4 months ago
Definitely not chosen plaintext attack.
KI
Kip 6 months ago
Wait, k>1 is a new technique? That's interesting!
ER
Ernie 6 months ago
I think it's actually linear cryptanalysis.
GE
Gennie 6 months ago
Sounds like differential cryptanalysis to me!
CH
Charlesetta 6 months ago
I agree with Merissa, differential is the way to go here!
GO
Goldie 6 months ago
Definitely not chosen plaintext attack, that's for sure.
KE
Keneth 6 months ago
Wait, is this really a new technique? I thought k=1 was the limit.
LE
Lemuel 7 months ago
I think it's actually linear cryptanalysis, though.
ME
Merissa 7 months ago
Sounds like a classic case of differential cryptanalysis!
MI
Misty 7 months ago
I thought chosen plaintext attacks were more about manipulating input to get useful output, so this doesn't seem like that. I lean towards differential cryptanalysis, but I’m not completely confident.
VA
Vannessa 7 months ago
This might be integral cryptanalysis, but I can't recall the details about how it works with the k bits. It feels like a tricky question!
AN
Annmarie 7 months ago
I remember studying linear cryptanalysis too, but this seems different since it focuses on holding bits constant. I wonder if it's really differential or something else entirely.
FR
Francis 7 months ago
I think this sounds a lot like differential cryptanalysis, especially since it mentions holding bits constant. But I'm not entirely sure about the specifics with k.
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