Cryptanalysis on a "partial file" encrypted using a Block Cipher?
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Good Day, Say a text document (100 bytes) was encrypted using a Block Cipher (say DES). However, during transmission, parts of the files have been lost and the file size was reduced to 90bytes (Hypothetical Situation). The lost part is randomly distributed (not only in the end). Would it still be possible to conduct cryptanalysis on that file and recover at least part of file? (Knowing that DES is susceptible to Linear and Differential Cryptanalysis) Waiting for some inputs! :laugh: Thanks!
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
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Good Day, Say a text document (100 bytes) was encrypted using a Block Cipher (say DES). However, during transmission, parts of the files have been lost and the file size was reduced to 90bytes (Hypothetical Situation). The lost part is randomly distributed (not only in the end). Would it still be possible to conduct cryptanalysis on that file and recover at least part of file? (Knowing that DES is susceptible to Linear and Differential Cryptanalysis) Waiting for some inputs! :laugh: Thanks!
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
Why not just resend it? Or are you concerned about someone intercepting a portion of the transmission and trying to decipher that portion and getting most of the message? If so, use something stronger than DES...
"The clue train passed his station without stopping." - John Simmons / outlaw programmer "Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
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Why not just resend it? Or are you concerned about someone intercepting a portion of the transmission and trying to decipher that portion and getting most of the message? If so, use something stronger than DES...
"The clue train passed his station without stopping." - John Simmons / outlaw programmer "Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
Uhmm, No. I have a school project related to cryptography. My design is particularly related to "Personal File Encryption". What I did was divide the plaintext into smaller blocks, chain them, then store 10% of those blocks in a flash drive, thus making it a "physical key". *By chaining those blocks, they have become "interdependent" of each other. So, would it be possible to perform cryptanalysis on a ciphertext that isn't complete?
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
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Uhmm, No. I have a school project related to cryptography. My design is particularly related to "Personal File Encryption". What I did was divide the plaintext into smaller blocks, chain them, then store 10% of those blocks in a flash drive, thus making it a "physical key". *By chaining those blocks, they have become "interdependent" of each other. So, would it be possible to perform cryptanalysis on a ciphertext that isn't complete?
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
Ian Uy wrote:
So, would it be possible to perform cryptanalysis on a ciphertext that isn't complete?
Possibly, but they probably wouldn't get very far.
"The clue train passed his station without stopping." - John Simmons / outlaw programmer "Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
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Uhmm, No. I have a school project related to cryptography. My design is particularly related to "Personal File Encryption". What I did was divide the plaintext into smaller blocks, chain them, then store 10% of those blocks in a flash drive, thus making it a "physical key". *By chaining those blocks, they have become "interdependent" of each other. So, would it be possible to perform cryptanalysis on a ciphertext that isn't complete?
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
From your first post I was going to advise you to think of it this way: You've compressed the plaintext before encryption to remove any entropy. You've then encrypted it, and the data is still the same size. So there can't possibly be any error recovery information. However reading your second post, I'm not sure what technique you are using. It sounds like you are removing 10% of the cleartext and putting it somewhere else. Removing en percen of the ltters wil be trivil to readjust by loking atit.
Mark Churchill Director, Dunn & Churchill Pty Ltd Free Download: Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.
Alpha release: Entanglar: Transparant multiplayer framework for .Net games. -
From your first post I was going to advise you to think of it this way: You've compressed the plaintext before encryption to remove any entropy. You've then encrypted it, and the data is still the same size. So there can't possibly be any error recovery information. However reading your second post, I'm not sure what technique you are using. It sounds like you are removing 10% of the cleartext and putting it somewhere else. Removing en percen of the ltters wil be trivil to readjust by loking atit.
Mark Churchill Director, Dunn & Churchill Pty Ltd Free Download: Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.
Alpha release: Entanglar: Transparant multiplayer framework for .Net games.Hmmm, say I have a simple message that contains:
Hello World, I love cryptography!
The first thing I would do is XOR X[n] and X[n+1] until X<=Message.Length (Like Block Chaining). This makes the text no longer a cleartext but a ciphertext. Then, I will randomly remove parts of the chained message. Since by chaining them, they have already become interdependent with each other and without those missing values, it will be hard to "crack" it. The missing part, in turn, was turned to a key. (Or an Initial Vector). :)
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
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Hmmm, say I have a simple message that contains:
Hello World, I love cryptography!
The first thing I would do is XOR X[n] and X[n+1] until X<=Message.Length (Like Block Chaining). This makes the text no longer a cleartext but a ciphertext. Then, I will randomly remove parts of the chained message. Since by chaining them, they have already become interdependent with each other and without those missing values, it will be hard to "crack" it. The missing part, in turn, was turned to a key. (Or an Initial Vector). :)
It is said that the most complex structures built by mankind are software systems. This is not generally appreciated because most people cannot see them. Maybe that's a good thing because if we saw them as buildings, we'd deem many of them unsafe.
My gut feel is that your effective keyspace will be each contiguous block of text removed. As the plaintext is fairly predictable then the keyspace is reduced considerably. Once the first block is recovered, then the others will fall in sequence. If you are removing random characters then your effective keyspace is probably around 3 or 4 bit if the plaintext is a written language. I would, as always, recommend using a standard method of protecting your data if security is important.
Mark Churchill Director, Dunn & Churchill Pty Ltd Free Download: Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.
Alpha release: Entanglar: Transparant multiplayer framework for .Net games.