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EC-Council 212-81 Exam - Topic 6 Question 61 Discussion

Posted by Tawna on Aug 17, 2025 at 01:55 PM

Which of the following uses an 80 bit key on 64 bit blocks?

Suggested Answer: A

Skipjack

https://en.wikipedia.org/wiki/Skipjack_(cipher)

Skipjack uses an 80-bit key to encrypt or decrypt 64-bit data blocks. It is an unbalanced Feistel network with 32 rounds.

Incorrect answers:

Twofish - is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. It was one of the five finalists of the Advanced Encryption Standard contest, but it was not selected for standardization. Twofish is related to the earlier block cipher Blowfish.

AES - For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.

DES - Data Encryption Standard is a symmetric-key algorithm for the encryption of digital data. Although its short key length of 56 bits makes it too insecure for applications, it has been highly influential in the advancement of cryptography.


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22 comments · newest first
RO
Rolland 10 months ago
Really? I didn't know Skipjack had an 80-bit key!
HA
Hassie 10 months ago
Wait, isn't AES the more modern option?
EL
Elouise 10 months ago
Totally agree, it's definitely Skipjack!
LA
Larae 10 months ago
Skipjack uses an 80-bit key on 64-bit blocks.
AM
Amalia 11 months ago
I thought DES was the one with 64-bit blocks?
JE
Jettie 11 months ago
AES uses 128-bit blocks, so it can't be the answer here.
MA
Marica 11 months ago
Twofish is definitely not the right answer; I recall it uses larger blocks.
MI
Mitsue 12 months ago
I remember practicing a question about DES, but I don't think it has an 80-bit key.
HE
Herman 12 months ago
I think Skipjack uses an 80-bit key, but I'm not sure about the block size.
DE
Delfina 1 year ago
I'm pretty confident Skipjack is the correct answer here. The key and block sizes match the question.
MA
Malcolm 1 year ago
I'm a bit unsure about this one. I'll need to review my notes on the different encryption algorithms to be sure.
TA
Tamekia 1 year ago
Skipjack uses an 80-bit key, and the question specifies 64-bit blocks, so I think that's the one.
HA
Han 1 year ago
Okay, I know AES uses a 128-bit key, so that's not the right answer. Let me consider the other options.
AZ
Azalee 1 year ago
Hmm, this looks like a cryptography question. I'll need to think through the key sizes and block sizes of the different algorithms.
SO
Sophia 1 year ago
Haha, this question is a real Twofish in a barrel! AES is the way to go, guys.
TR
Trinidad 1 year ago
DES? Really? I thought that was ancient history. Clearly, the answer has to be AES.
VI
Vilma 9 months ago
↳ replying to Trinidad
DES still has its uses, surprisingly!
JA
Janet 10 months ago
↳ replying to Trinidad
Skipjack is interesting, but not the answer.
CO
Colette 10 months ago
↳ replying to Trinidad
AES is definitely more modern.
AL
Alana 11 months ago
↳ replying to Trinidad
I thought DES was outdated too!
NI
Nickole 1 year ago
Ugh, I always get confused between Skipjack and Twofish. They just sound so similar!
MY
My 1 year ago
↳ replying to Nickole
A) Skipjack uses an 80 bit key on 64 bit blocks.
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