Cryptanalysis is the part of cryptology dedicated to the mathematical analysis of the weaknesses of cryptographic algorithms, the goal being to defeat some of the security properties that the algorithm should fulfill, e.g. decrypting data which has been symmetrically encrypted with substantially ...

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Crypt-analysis methods for breaking or finding weakness in an encryption algorithm? [closed]

How cryptanalysts work on an algorithm related to diffusion/confusion factors in order to find a weaknesses in an algorithm, for example how cryptanalysts could find weakness on DES? is there methods ...
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1answer
95 views

Does it increase the security if we split data to n pieces and encrypt each one with different key and different algorithm?

For example: a 10 MB file will be sliced to 10 pieces (each 1 MB) and then dispersed between network nodes. Each node will encrypt it with its own key and different algorithm (AES, TwoFish, Blowfish, ...
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2answers
131 views

How can an attacker identify the encryption method with only ciphertext?

Assume that attacker only could obtain ciphertext, but knows that method is symmetric. Is there a way to find which algorithm was used for the encrytion? And in general, if attacker knows the ...
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1answer
47 views

Which parameters can I use to analyse my cipher? [closed]

I have made a new methodology for a symmetric key cryptography in which I have used matrix operations, a boolean function and ASCII conversion. Please suggest me the possible parameters to judge my ...
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1answer
77 views

Tell type of encryption if given both input and output strings [closed]

I have the string Thisisatest that is encoded as MDQ4MGFhMzRhYTNkYjM1OGIzN2NkZTJhYjZiNjUzMjY= and I am trying to find out what encryption is used here. I think that the encoded string is base64 ...
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2answers
249 views

How is a hash's algorithm detected based on the hash?

I was reading an Ars Technica article this morning and came across the following towards the end (emphasis mine): Equation Group included six other hashes in different exploits that remain unknown ...
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1answer
196 views

Soundness of GRC.com Haystack padding concept [duplicate]

I was wondering how sound is the concept presented by the Gibson Research Corporation (see below if you do not want to follow the link) about simple passwords (= very easy to remember) with the ...
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1answer
635 views

Is there a method to get plain-text from cipher-text in HMAC SHA-1, given that the key is known?

This is technically not even an attack. We have all the resources at hand, except for the original plain-text. We have the cipher-text (to be converted back to plain-text), as well as the key. The ...
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1answer
151 views

Can a botnet be used to effectively break encryption keys?

Can a botnet amass and coordinate enough computing power to break encryption keys that are typically considered to be secure (through brute force)? If this is the case, do we need to make our ...
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1answer
70 views

Calculating the breakability of a given encryption method

I will soon be doing a very important project for school. The main goal of my project is to find a mathematical way to calculate the breakability of a given encryption method of ciphertext. Is there ...
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2answers
372 views

Find DES encryption key having input and encrypted output

Having the source string: S3nh4#1 And the generated encrypted string: csf7259aT07Rw Using this script, it identified the algorithm used to encrypt as DES(Unix) I wonder if it is possible (in ...
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1answer
125 views

How to cryptoanalyze a one time pad that uses a plain text document as the pad?

I have read that in order for a one time pad to be truly secure, the pad itself must be random data. Given the practical difficulty of sharing a secure random pad, I was wondering what would be the ...
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1answer
31 views

Key Extraction via electrical signal processing

Looking for a link to what I believe was recent research that was similar to "RSA Key Extraction via Low-Bandwidth Acoustic Cryptanalysis" - but instead of being based on acoustic emanations, the ...
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5answers
265 views

Is it ever possible to crack an encryption key character by character?

In movies and TV shows, characters are often depicted using devices and applications that are able to determine an encryption key or passcode character by character (or digit by digit). I am a ...
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2answers
162 views

Crack Unknown Encryption [closed]

I was challenged by a friend to decrypt a piece of text that was somehow encrypted. The encrypted text is the following: ...
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1answer
109 views

What keeps the private key safe if an attacker has both clear and encrypted copies of a message and the public key?

Let's say someone obtained a message in both clear text and in its encrypted copy with asymmetric cryptography, like RSA-2048. He also has the public keys. Is the private key still undiscoverable? ...
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2answers
135 views

Cryptanalysis of encrypted data at rest

Imagine I have a file encrypted using AES CBC mode with a key and a random IV. The attacker access to the encrypted text and the IV used but not the key. In this scenario there is no vulnerability ...
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1answer
223 views

Knowing Input&Output, How to determine encode method and the passkey that was used in encoding?

I've looked on this site and on SE. but I couldn't get a handle on this. Is there a way to find what type of encoding (and/or encode key) is being used? For example, I am testing a web ...
3
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1answer
257 views

Klein and PTW wep attack

I'm working on an implementation of Klein's wep attack. For that, I've set up a router with wep encryption and collected 50,000 unique IVs from it. I tried only calculating K[0], meaning - the first ...
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2answers
471 views

Is AES encryption vulnerable?

I was reading weaknesses in AES encryption. Unfortunately, I have a website that uses AES: Its database is almost entirely AES encrypted. Is there a real threat? Would it be worth to refactor the web ...
3
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1answer
487 views

Cracking DES(Unix)/MD5 ARP

This is a basic exemple of Unix Pass Encryption. I have little Hash of MD5 ARP : user50:$apr1$w7YNTrjQ$0/71H7ze5o9/jCnKLt0mj0 user60:$apr1$AIw2h09/$Ti0TRlU9mDpCGm5zg.ZDP. I need to find the pass ...
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1answer
67 views

Frequency Analysis [closed]

I have started looking into Crytography, and the obvious starting point is frequency analysis. As a task for myself I thought it would be good to compile a script which could be used for perform the ...
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2answers
174 views

Does Known plaintext attacks lead to exposure of the key?

The back-story is long and boring so I will get down to the meat of the argument. I say that if a professional code breaker has a bunch of data, the encoded version of said data and the encoding ...
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2answers
584 views

Google's usage of RC4

I was reading about Google's usage of RC4 and an answer on stackexchange website stated the following: I know Google uses RC4 for most of its services, and this is the reason one shouldn't keep ...
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4answers
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What kinds of encryption are _not_ breakable via Quantum Computers?

There's the recent article NSA seeks to build quantum computer that could crack most types of encryption. Now I'm not surprised by the NSA trying anything1, but what slightly baffles me is the word ...
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2answers
102 views

Facing hard encryption [closed]

I have a little problem with encryption. I have this cipher text "AA969CF9657F77C597C8EAFF1594D59374E4977F" and i know that correspond to "http://jogos.meo.pt/". I have another samples, but i can´t ...
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2answers
317 views

cold boot attacks

To quote the wikipedia article on Cold Boot Attacks: In cryptography, a cold boot attack (or to a lesser extent, a platform reset attack) is a type of side channel attack in which an attacker with ...
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4answers
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At what point does adding more iterations to PBKDF2 provide no extra security?

If my true passphrase is used only to generate a hash which is used as the cipher's actual key, doesn't that mean it's possible to try and brute force the cipher itself? I know it would take an ...
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2answers
361 views

What is (“ASCII” redundancy) which is said to be required to retrieve the original plain text in 2 times pad?

Sorry for the long title :$ In a video speaking about attacks on the one time pad which uses psudorandom generators (PRG), It's said that Eve can retrieve the plain text of 2 messages that have been ...
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1answer
141 views

Timing analysis attack and cryptosystem

Why is a “Timing Analysis Attack” a problem for a cryptosystem? I've been trying to learn security, and have a question about timing analysis attack.
12
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2answers
748 views

Correct way to get a number from 0-9 from a random byte?

If I have a good random number generator that gives me a byte of data at a time, and I want to extract a random decimal digit of 0 to 9 from that byte stream, what is the correct way to do that? At ...
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1answer
181 views

The basics of cryptanalysis [closed]

There are a lot of books on encryption. Is there a must read intro, something like Smashing the Stack for Fun and for profit, that more or less everyone reads?
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1answer
153 views

Who can view my https browsing habbits? [closed]

I was wondering about HTTPS security and how easily is compromised. I have already read the similar threads in here, but I have some more questions: Let's say I am searching something at Google. ...
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1answer
464 views

Known plaintext; What cipher is being used here? [closed]

plaintext: CANDY VERY CRANBERRY ciphertext: TXOtWjYhVk 8&O$4AmSA plaintext: http ciphertext: cZf. plaintext: http ciphertext: r5Hz This is definitely somehow decodable from ...
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2answers
576 views

how to identify plain text from cipher [closed]

I am trying to find what encryption algorithm has been used in this code original text: 11011698 encrypted text/cipher: uIC4hZFECIAYMi%20FWxamjQ== original text:11008569 encrypted text/cipher: ...
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2answers
736 views

How can i calculate the number of possible passwords?

I have found a flaw in a site where the password reset feature resets passwords in the following format UpperCaseLetter-Number-LowerCaseLetter-Number-LowerCaseLetter-Number-UpperCaseLetter ...
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7answers
758 views

How easy is it to find a password in a huge text file?

Say that my password is PASSWORD1 I have a 10MB jumbled text file. I hide my password in two parts in the text, between > and < so I can find it myself. Then I put the 2 parts together and add the ...
76
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8answers
10k views

How would one crack a weak but unknown encryption protocol?

I was reading this interesting question: Is my developer's home-brew password security right or wrong, and why? It shows a weak home-brew algorithm developed by "Dave", and the answers discuss ...
2
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1answer
322 views

Legality and ethics of cryptanalysis on password hashes

I'm working on my dissertation concerning cryptanalysis on password hashes. I'd like to delve into the legal and ethical aspects of cryptanalysis, however, seeing as I'n not at all well versed in law ...
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2answers
287 views

Remedy for not having filled the disk with random data?

Filling a large HDD with /dev/urandom prior to encryption can be extremely slow (even with netcat, multiple instances in parallel, etc) and for this reason I'm sure a lot of users skip this advice ...
3
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2answers
288 views

is it easier to get the original password if you have multiple hashes of it?

Most users tipically use the same password for multiple applications. Let's say all of these applications hash the password in some way. Would it be easier for an attacker to get the original password ...
3
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0answers
282 views

Can an attacker guess my password length from a hash? [duplicate]

Possible Duplicate: Possible to detect password length from hash? Is doubling your password adds more security? Considering I do not provide him any personal information relating to it, are ...
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2answers
2k views

Tool for generating MD4 collisions

There are a lot of research papers available online that discuss vulnerabilities of MD4 algorithm, but I couldn't find any implementation of these. Uptill now I have used tools like John the Ripper ...
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2answers
1k views

How to test security of an encryption algorithm?

What are the standards methods to test the quality of an encryption algorithms. Secondly if i am trying to implement an encryption algorithm then what practices should i adopt?
2
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2answers
842 views

Determine encoding/hashing methods used based on knowing the input and output only?

If I know the initial value of a string and the resulting hash but have no access to the system that produces the output, how can I determine what has actually occurred so I can reproduce the hashing ...
7
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1answer
493 views

Identifying, analyzing, and predicting weak session cookies

To elaborate on this, I'm looking at this from the perspective of a hacker/penetration tester. Many times I have seen web applications that I know have weak cookies. I can tell this because I can ...
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2answers
94 views

Encryption app stroring the password

The encryption app that we are using seems to generate the same output for the same input. That is bad right? I'm not smart enough to understand the scheme being used though. The header of each ...
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1answer
302 views

How key_derivation and key_verification functions are implemented of a 7-zip archive's encryption mechanism?

I am curious about how password recovery works for password protected files. And I want to know the exact flow of the 7-zip encryption mechanism :) !! 7-zip uses the AES-256 encryption algorithm in ...
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1answer
290 views

Can I combine two of SHA-3 candidates cryptography hash functions and obtain more secure Algorithm? [duplicate]

Possible Duplicate: Are different hash algorithms ever used together? For example, Is possible to combine (Concatenate or Chain or XOR) Skein SHA-3 candidate with Grostl SHA-3 candidate to ...
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2answers
3k views

Estimating the size of a rainbow table

What are rainbow tables and how are they used? Gives a very precise answer about what rainbow tables are and how they are used. I had always confused hash-tables and rainbow tables. My question is ...