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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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 ...
2
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1answer
110 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? ...
2
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2answers
1k views

How effective have statistical methods been at breaking encryption?

If we look at how statistical engines run on-line translators, and how they are built, we see that they look at a new language and run a statistical model over it searching for what's probably the ...
2
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2answers
527 views

GOST cipher test vectors

Does anyone know where to find test vectors for the GOST cipher? I have been looking around for quite some time, and have been unable to find anything. I know that the sboxes are dependent on the ...
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
132 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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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
182 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
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
194 views

Stripping / appending characters from user password before hashing to conceal it forever?

I had this idea to permanently conceal user password by requiring minimum length then stripping certain characters. For example if the user password is secret123, the system will strip it down to ...
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2answers
136 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
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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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 ...
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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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2answers
176 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
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
99 views

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
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.
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1answer
282 views

any small idea to decode this algortihm from php script [closed]

So I think the algorithm is based on the php function ENCODING_decode defined in includes/encoding.php (which i don't have) . The encoded result $xId_campaign_encoded from the php script has ...
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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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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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3answers
504 views

Best protection against a “chosen-ciphertext” attack?

What is the best protection against a "chosen-ciphertext" attack when transmitting (=streaming) secured (=crypted) data via networks using the TCP protocol?
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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
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
585 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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1answer
32 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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2answers
319 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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1answer
303 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
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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1answer
155 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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2answers
377 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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2answers
163 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
79 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
577 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
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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votes
3answers
460 views

Would this kind of encryption be good at anything?

I have put much thought into this very simple algorithm and I have no clue if it was thought before... But I think it should have. I also know nothing about other encryption algorithms so I can't tell ...