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 ...
4
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3answers
4k views

Vigenere Cipher - help with decryption (by hand)

So this is a Vigenere cipher-text EORLL TQFDI HOEZF CHBQN IFGGQ MBVXM SIMGK NCCSV WSXYD VTLQS BVBMJ YRTXO JCNXH THWOD FTDCC RMHEH SNXVY FLSXT ICNXM GUMET HMTUR PENSU TZHMV LODGN MINKA DTLOG HEVNI ...
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2answers
5k views

Cracking a linear congruential generator

I was recently listening to the security now podcast, and they mentioned in passing that the linear congrunential generator (LCG) is trivial to crack. I use the LCG in a first year stats computing ...
2
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2answers
125 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
87 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, ...
2
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1answer
243 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 ...
0
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1answer
45 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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4answers
6k views

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
238 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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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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1answer
70 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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1answer
132 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 ...
3
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2answers
413 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 ...
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2answers
339 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 ...
3
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5answers
260 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 ...
62
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8answers
147k views

How to determine what type of encoding/encryption has been used?

Is there a way to find what type of encryption/encoding is being used? For example, I am testing a web application which stores the password in the database in an encrypted format ...
4
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1answer
152 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 ...
7
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1answer
583 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
64 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 ...
1
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1answer
120 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 ...
0
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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 ...
33
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5answers
22k views

Should RSA public exponent be only in {3, 5, 17, 257 or 65537} due to security considerations?

In my project I'm using the value of public exponent of 4451h. I thought it's safe and ok until I started to use one commercial RSA encryption library. If I use this exponent with this library, it ...
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2answers
131 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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2answers
154 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: ...
2
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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? ...
12
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2answers
725 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 ...
1
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1answer
199 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
349 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 ...
33
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2answers
46k views

How to estimate the time needed to crack RSA encryption?

How to estimate the time needed to crack RSA encryption? I mean the time needed to crack Rsa encryption with key length of 1024, 2048, 3072, 4096, 5120, 6144, 5120, 7168, 8192, 9216, 10240, 11264, ...
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3answers
1k views

Length of CSRF Token

Is there any standard length of the token which should be used while generating the random tokens? Should we use the same standard which we use for generating Session IDs?
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3answers
443 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 ...
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2answers
548 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 ...
3
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1answer
467 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 ...
29
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8answers
3k views

If someone breaks encryption, how do they know they're successful?

Let's say I have a file containing a random bunch of bits and then I encrypt it using some modern algorithm (Blowfish, AES, or whatever). If someone captures the file and mounts a brute force attack ...
0
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1answer
66 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 ...
0
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2answers
167 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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votes
2answers
101 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
312 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 ...
3
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3answers
394 views

How to optimize compressed file cracking?

I'm currently doing research on cracking encrypted, compressed files (specifically: uif, zip, 7z, dmg). Looking at all the utilities out there, it seems the time it takes to crack something is ...
9
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4answers
1k views

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 ...
0
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1answer
140 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.
28
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7answers
16k views

Where can I learn cryptography/cryptanalysis the hard way, without going to school ? Any good book?

I'm not so bad at mathematics: I know what are p-list and p-combinations, I know matrix algebra, I know what a XOR is, I know how to tell if number is a prime, etc: I'm not the programmer who hates ...
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1answer
176 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
149 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. ...
5
votes
1answer
455 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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votes
2answers
555 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: ...
0
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1answer
281 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 ...
4
votes
2answers
697 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 ...
6
votes
7answers
726 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
votes
8answers
9k 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 ...