Which technique can be used to make an encryption scheme more resistant to a known plaintext attack?
A. Hashing the data before encryption
B. Hashing the data after encryption
C. Compressing the data after encryption
D. Compressing the data before encryption
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These kind of questions are realy annonying as none of the provided answers is completly correct.
For the compression part i agree on the fact that this is not a security subject and compressed information can be easly rebuilt. for the remaining answers i dont anderstand how can hashing be used for an encryption purpose except if it can be cancatineted in some way with the plan/ciphertext ! in this case it should be precised on the the question.
Compressing is NOT encryption. The cryptographically best way is 1. Hash, and 2. Encrypt. Compressing just helps to save more space nothing else.
Hashing is a method of one-way encryption. Essentially, ‘A’ says, “Encrypt the data before encrypting.” This makes no sense. Also, through hashing, you are not supposed to be able to retrieve the original copy of the information. Hashes are created to compare hashes. If you download a file from the internet, they provide the hash of that file. You can re-hash the file to verify the hashes match. Works the same way with ATM’s pins. There’s a hash of your pin stored, and when you enter your pin, a hash of what you entered is compared to the stored hash. This, way your pin is not stored in plaintext anywhere. You don’t reverse the hash – that is not supposed to be possible.
Compressing is not encryption. Compressing is reducing the file size as much as possible by combining bits in the data. More accurately, data compression, source coding, or bit-rate reduction, is the process of encoding information using fewer bits than the original representation. This is not done for a security purpose but has the added benefit of requiring the data to be decompressed to read.
If I were to send data to you through an email for example, I would compress the data as much as possible, and then I would encrypt the compressed data.
I am agreeing with the others here, in that D is the correct answer.
I think compression is also a type of encryption, and compression will have data processing performance problems, so the answer is A, what do you think?
Sending E[hash(PlainText)] to a receiver, there is no way for the receiver to decrypt the plain-text. So, A cannot be the answer. IMO D is the answer. Also the problem did not say that we are appending the plain-text ( as in a digital signature)
I think D is correct answer,
If hashing the data, receiver can’t get original data from hash.
I bet on A.
The question is asking about an encryption scheme. You will send both the data and the hash to the receiver.
still need to consider the known plaintext attack in the question. D is the correct answer
Yes, D should be correct – when plaintext is hashed and then encrypted, the receiver will decrypt a message and get hash of the plaintext, but from this hash will not get raw plaintext
I agree with D.
Even if the original plaintext is known, if the compressed data is not known, the known plaintext attack is not performed.
For example, a ZIP Deflate has a degree of freedom in compression.
Different compressed data can be created depending on the degree of freedom of compression, but when they are decoded, they become the same file.