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EC-Council 212-81 Exam - Topic 2 Question 30 Discussion

Posted by Torie on Apr 19, 2024 at 07:47 AM

If Bob is using asymmetric cryptography and wants to send a message to Alice so that only she can decrypt it, what key should he use to encrypt the message?

Suggested Answer: D

Vigenre

https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher

The Vigenre cipher is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.

First described by Giovan Battista Bellaso in 1553, the cipher is easy to understand and implement, but it resisted all attempts to break it until 1863, three centuries later. This earned it the description le chiffre indchiffrable (French for 'the indecipherable cipher'). Many people have tried to implement encryption schemes that are essentially Vigenre ciphers. In 1863, Friedrich Kasiski was the first to publish a general method of deciphering Vigenre ciphers.


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34 comments · newest first
SH
Shalon 11 months ago
I thought private keys were for encryption, not public ones?
MA
Magdalene 11 months ago
Yup, Alice's public key is the right choice!
LA
Laurene 11 months ago
Wait, why not just use his own private key? Seems off.
EM
Emiko 12 months ago
Totally agree, that's how asymmetric encryption works!
JE
Jesusa 12 months ago
He should use Alice's public key to encrypt the message.
AM
Amie 1 year ago
I’m pretty confident that using Alice's public key is the correct answer, as it ensures only she can decrypt it with her private key.
ST
Stevie 1 year ago
I feel a bit confused; I thought Bob's private key was involved somehow, but that doesn't seem right for this scenario.
DO
Dottie 1 year ago
I remember a practice question where we had to decide which key to use for encryption, and it was definitely the recipient's public key.
JA
Janine 1 year ago
I think Bob should use Alice's public key to encrypt the message, but I'm not entirely sure if that's the right approach.
MA
Martin 1 year ago
I'm not too sure about this one. Asymmetric cryptography can be tricky, and I don't want to overthink it. I'll go with Alice's public key, but I'm not 100% certain that's the right answer.
VI
Viola 1 year ago
Okay, let me think this through. Bob wants to send a message to Alice, and he's using asymmetric cryptography. So he needs to use Alice's key to encrypt the message, and only Alice will be able to decrypt it with her private key. I'm pretty confident that the answer is Alice's public key.
MA
Malcolm 1 year ago
Hmm, this seems straightforward. I think Alice's public key is the right answer since Bob wants to encrypt the message so that only Alice can decrypt it.
RE
Reena 1 year ago
I'm a bit confused. Isn't the whole point of asymmetric cryptography that you use the recipient's public key to encrypt the message? I'm not sure if I'm remembering that correctly.
AL
Alona 1 year ago
Hmm, I'm a bit unsure about this. I'll need to review my notes on service architecture patterns to make sure I understand the tradeoffs between these two approaches.
CO
Colette 1 year ago
This seems like a straightforward question about change management tactics. I'm pretty confident I can identify the right approach here.
KA
Kate 1 year ago
Hmm, I'm a bit unsure about this one. I need to carefully read through the details and think through the different types of antitrust violations.
TY
Tyra 1 year ago
Based on my understanding, the key here is that the chosen practice needs to assess and authorize any changes that could impact services. I think C - Change enablement is the best fit, as it's focused on managing the entire change process.
FE
Fernanda 1 year ago
I'm going with C, Alice's public key. Anything else would just be a recipe for disaster, like sending a message to myself and wondering why nobody can read it.
EM
Emmanuel 1 year ago
↳ replying to Fernanda
C) Bob's public key wouldn't work either. It's meant for encryption, but Alice wouldn't be able to decrypt with it.
QU
Quentin 1 year ago
↳ replying to Fernanda
B) Using Bob's private key would be a mistake. It's meant for decrypting, not encrypting messages.
AN
Anjelica 1 year ago
↳ replying to Fernanda
A) Alice's public key is the correct choice. It's the only way to ensure only she can decrypt the message.
SH
Shalon 1 year ago
Haha, Bob's public key? What is this, amateur hour? Of course it's Alice's public key, how else would she be able to decrypt it?
CA
Caren 1 year ago
↳ replying to Shalon
It's all about encryption and decryption, Bob needs to use Alice's public key for her to decrypt the message.
KR
Kristel 1 year ago
↳ replying to Shalon
Exactly, using Bob's public key would make no sense in this scenario.
CE
Cecil 1 year ago
↳ replying to Shalon
Bob should use Alice's public key to encrypt the message.
BE
Bea 2 years ago
Hmm, I was thinking Bob's private key, but now I'm second-guessing myself. Maybe I need to revisit the basics of asymmetric crypto.
FR
Freeman 2 years ago
I think it's Alice's public key, that's how asymmetric encryption works, right? Gotta keep those private keys private!
CA
Carmelina 1 year ago
↳ replying to Freeman
It's important to understand the role of public and private keys in asymmetric cryptography to keep communications secure.
JU
Jutta 1 year ago
↳ replying to Freeman
Exactly, Bob's private key should never be shared for security reasons.
MI
Mirta 1 year ago
↳ replying to Freeman
That's right, using Alice's public key ensures that only she can decrypt the message with her private key.
GO
Golda 2 years ago
↳ replying to Freeman
Yes, you're correct! Bob should use Alice's public key to encrypt the message.
LE
Lettie 2 years ago
No, because only I have the corresponding private key to decrypt it.
TE
Tegan 2 years ago
But wouldn't that mean anyone with my public key could decrypt it?
LE
Lettie 2 years ago
I think Bob should use my public key to encrypt the message.
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