Eccouncil 312-50 Exam - Topic 2 Question 105 Discussion

Actual exam question for Eccouncil's 312-50 exam

Question #: 105
Topic #: 2

Harper, a software engineer, is developing an email application. To ensure the confidentiality of email messages. Harper uses a symmetric-key block cipher having a classical 12- or 16-round Feistel network with a block size of 64 bits for encryption, which includes large 8 x 32-bit S-boxes (S1, S2, S3, S4) based on bent functions, modular addition and subtraction, key-dependent rotation, and XOR operations. This cipher also uses a masking key(Km1)and a rotation key (Kr1) for performing its functions. What is the algorithm employed by Harper to secure the email messages?

ACAST-128

BAES

CGOST block cipher

DDES

Show Suggested Answer

Suggested Answer: A

by Wilson at Apr 05, 2025, 04:26 PM

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Jody

7 months ago

I’m leaning towards CAST-128, but I’m not sure.

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Jaclyn

7 months ago

Definitely not GOST, that one's different.

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Ronna

7 months ago

I think it's AES, though. The S-boxes are a big hint!

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Annmarie

8 months ago

Wait, 12-16 rounds? Isn't that a bit outdated for security?

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Brice

8 months ago

Sounds like DES to me, with that Feistel structure.

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Sang

8 months ago

The mention of modular addition and key-dependent rotation makes me think of GOST, but I could be mixing it up with other ciphers.

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Herminia

8 months ago

I practiced a question on symmetric-key ciphers, and I think CAST-128 was mentioned, but this description seems more aligned with DES.

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Pearlie

8 months ago

I'm not entirely sure, but I feel like the use of S-boxes and the block size points more towards AES.

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Elfrieda

9 months ago

I remember studying the Feistel network structure, and I think it might be related to DES since it uses a similar approach.

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Felton

9 months ago

This is a tricky one. The question gives a lot of specific technical details, but it's not immediately clear which cipher it's describing. I'll need to review my knowledge of symmetric-key block ciphers and try to match the features mentioned to the available options.

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Hildegarde

9 months ago

Okay, let's see. The 12- or 16-round Feistel network with 64-bit block size and the use of S-boxes based on bent functions sounds a lot like the GOST block cipher. I think that's the algorithm they're asking about.

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Ettie

9 months ago

Hmm, I'm a bit unsure about this one. The details provided are quite technical, and I'm not entirely familiar with all the cryptographic concepts mentioned. I'll need to carefully re-read the question and think through the options.

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Ming

9 months ago

This question seems pretty straightforward. The description of the cipher's features like the Feistel network, S-boxes, and key-dependent operations points to CAST-128 as the algorithm used.

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Shala

1 year ago

Wait, is this a trick question? I bet the answer is 'All of the above' and Harper is actually using a top-secret, government-grade encryption algorithm that's a mix of everything!

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Elly

1 year ago

User 3: Maybe it's actually GOST block cipher, who knows!

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Leatha

1 year ago

User 2: No, I believe Harper is using DES for encryption.

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Lavera

1 year ago

User 1: I think the answer is AES.

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Tamar

1 year ago

Hmm, this sounds like a fancy version of good old DES. I'm going to have to go with option D on this one.

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Claribel

1 year ago

Ooh, the masking key and rotation key make this one tricky. I'm going to say GOST block cipher, as it's a lesser-known algorithm that uses similar techniques.

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Coral

1 year ago

Haha, this question is a bit of a brain-teaser! I'm going to go with AES, as it's the current industry standard for symmetric-key encryption.

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Vannessa

1 year ago

User 3: AES it is then, sounds like the best option for Harper's email application.

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Leanora

1 year ago

User 2: I agree, AES is definitely a strong contender for securing email messages.

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Brice

1 year ago

User 1: I think AES is the right choice, it's widely used for encryption.

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Elmer

1 year ago

Sounds like a pretty complex encryption algorithm! I think it's CAST-128, as it fits the description of a 12- or 16-round Feistel network with 64-bit blocks and large S-boxes.

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