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Questions tagged [md5]

MD5 is a hash function that is no longer considered secure from a cryptographic point of view. Therefore, it should only be used for backward compatibility.

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Getting MD5 hash without knowing key

My intuition is that this is probably fairly unfeasible, but I'd like to ask anyway to see if I'm missing anything. I have a list of 8-byte input (e.g. in hexadecimals: ...
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Trying to understand length recovery attack on EAP-MD5

I'm failing to understand how length recovery attack works in EAP-MD5 described in this paper on page 6: https://inria.hal.science/hal-01534313/document I setup ...
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How to generate an arbitrary file matching a given MD5 hash? [duplicate]

I have an MD5 hash and need to generate a file that matches it. There are absolutely no constrains on the contents of said file, it can be binary gibberish. The only important thing is that it matches ...
Werdck's user avatar
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What are the chances of two 5-symbol strings derived from md5 colliding?

I'm taking 2 medium-length strings (50-70 chars) and hash them using md5 to get results like d2ae4f4919a10958e2c603782f0ec1cc, then recording the first 5 symbols of ...
ADC's user avatar
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Is it safe to sign a short token with salted md5

I want to generate some tokens for client as http cookie can I md5 them with salt and then use "<random token>"+"<md5>" as the token ...
xingxing hao's user avatar
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Iterated hash functions

In this image, It describes the basic idea of an iterative hash function. I am confused as to why the i value is set to be m+t+1 ...
Simon Balfe's user avatar
3 votes
1 answer
175 views

Is it possible to sign in to a website using two different passwords using an MD5 hash collision?

I wanna do an experiment. I wanna see if it's possible to sign in to an outdated website that still uses MD5 to store passwords (there are surprisingly still a lot) with two different passwords. For ...
Domino's user avatar
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3 votes
1 answer
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Quickest way to find MD5 collision

I'm trying to find a MD5 hash collision between 2 numbers such that one is prime and the other is composite (at most 1024-bit). I'm using fastcoll with random prefixes for each iteration. For this I ...
infinite-blank-'s user avatar
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2 answers
385 views

How to calculate probability of cracking a password from entropy?

I am working on a project for my maths assessment where I research the effect of complexity and length on a given password. Currently, I am working on calculating the probability of guessing a ...
Ember's user avatar
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101 views

Practical attack on MD5(key || fixed-length-message) as MAC?

I wonder if there is any practical attack on MD5(key || fixed-length-message).
edo1's user avatar
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How were the initial values for the chaining variables in MD5 determined?

The original description of the MD5 algorithm initializes the values of A, B, C, and D to the following: ...
jaip's user avatar
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MD5 , inputs larger than 512 bits

So I get how it works for inputs shorter than $512$, but as for larger inputs "In the case where the remaining input data is exactly $448$ bits long, an entire extra block would need to be added ...
tiredpotato's user avatar
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Which hash functions provide 128 bit resistance?

I was wondering out of the functions (MD5, SHA-1, SHA-256, and SHA-512), do all provide 128-bit pre-image resistance and 128-bit second-image resistance? Also, out of these hash functions, do only SHA-...
CryptoGuru's user avatar
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Is it safe to initialize a random number generator with MD5 for pixel selection in image steganography?

This question is related to "Is it safe to initialize a random number generator with MD5?". But in the context of steganography we don't know which pixels have been selected to hide ...
Begoña Garcia's user avatar
1 vote
1 answer
181 views

Real world hash collision risk, for finite input; uniqueness only no data risk

I've got a comma-delimited list of identifiers that I need to use for uniqueness. MSSQL limits uniqueness to 1700 bytes, which according to my sampling, doesn't appear to be sufficient. hashes are the ...
Scott Brickey's user avatar
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356 views

Can I use half of 256 bit key as AES 256 IV?

After some google research, I have found out the IV used in AES 256 bit encryption must be a 128 bit key. My AES256 encryption is processed with key of random 256 bit key and IV generated of text ...
Kim Mỹ's user avatar
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How Davies–Meyer does work? [duplicate]

I am here so if I asked something wrong or in the wrong way please let me know. How to hash compression large data into the fixed size of the string. Edit: How Davies–Meyer does work? Take the example ...
Rohit Nishad's user avatar
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How to assign md5 of another file to one wav file? [duplicate]

Good afternoon . Please tell me how to change the md5 hash of one wav file to the md5 hash of another wav file. I want to bypass the anti-cheat check on md5. Maybe there are online paid services? I ...
DEFJAM's user avatar
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2 votes
1 answer
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Which hashing function is good enough for session IDs?

Background I'm building a URL shortener, and the URL to shorten may contain a SessionId. For the URL shortener to not compromise the security of the SessionId, I must use a shortening strategy that ...
Ivan Rubinson's user avatar
1 vote
1 answer
292 views

Avoiding MD5 collision with secondary partial hashes

I am trying to design a VCS like program that determines if the files are the same by comparing their MD5 hashes. Then I read about MD5 collisions here, and I wonder if I can work around that by doing ...
Allahjane's user avatar
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1 answer
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how high is the possibility of getting a hash collision in text files?

Just for an example, let's say I downloaded "the adventures of tom sawyer" from gutenberg in .txt file format and saved it to my usb thumb drive. And as you can see, usb drive is not an ...
tadkov's user avatar
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2 votes
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How strong if I combine two hash functions, such as MD5(SHA256(input))?

If I try to do MD5(SHA256(input)), what is the strength of this so-called double hashing approach? Is it as strong as SHA256, or as strong as MD5, or as strong as ...
Neil Niu's user avatar
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1 answer
131 views

How blueimp JavaScript-MD5 works?

I have made some progress on the MD5 avalanche problem, https://github.com/221294583/crc32 It is said that CRC32 realizes avalanche through recursive XOR of polynomials and original values at the same ...
quxinna's user avatar
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Matching accounts across multiple data leaks via their hashed passwords

I've heard about several instances where OSINT researchers were able to match user accounts from multiple data leaks purely based on their hashed passwords, assuming accounts had the same password on ...
nisc's user avatar
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4 votes
2 answers
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How easy is it to fake a file hashed with three functions, CRC32, MD5 and SHA-1?

File-A is hashed with CRC32, MD5 and SHA-1. How easy is it to create a fake file-B that has the same hashes of file-A? CRC32, MD5 and SHA-1? Can an average PC with a GPU calculate a triple hash ...
user94388's user avatar
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1 answer
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Is it possible to have a hash in UUID form that ends with 16 characters instead of 12?

You may know how sometimes a hash in a URL may be in UUID format, which consists of groups of hex values separated by hyphens. In UUID format, I have come to learn that this hash takes the form: 8-4-4-...
Rikudou's user avatar
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1 answer
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Can someone please explain the "secret" and the "data" in the MD5 hashing algorithm?

I've been studying the MD5 hashing algorithm, and there is something that I just don't understand yet. They say that the server holds some sort or "secret" and that it appends some sort of &...
Rikudou's user avatar
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1 answer
419 views

Padding and the MD5 algorithm

In MD5, if M=100, how can we perform padding on it and how many blocks are needed in each round? These are general questions for understanding padding and rounds.
harpreet's user avatar
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112 views

Finding the cleartext password given its MD5

Given powerful GPU and PC hardware, is it realistic to recover a password in a few hours given a cleartext's MD5? Max chars are 95, and the maximum length of the password is 15 characters.
prtqwsq's user avatar
1 vote
1 answer
150 views

Is it possible to exploit MD5 weaknesses to create an artificial collision for a password?

If it is possible, could an attacker create a collision for an MD5 password in a database? Could they look at an MD5 hash output and figure out data that creates the same MD5 hash?
Practixal's user avatar
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Two Different Ciphers with Same MD5

I was wondering if someone could help explain md5 collision abit better. I found this resource: https://www.mscs.dal.ca/~selinger/md5collision/ where they provided an example of where two cipher texts ...
user16198894's user avatar
3 votes
2 answers
415 views

Use slow hashing to reduce digest size?

I have seen this question on MD5 replacement for 128 bit digests. It is said numerous times that having a 128 bit digest is impossible today because finding a collision would only require $2^{64}$ ...
JacopoStanchi's user avatar
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161 views

MD5 Algorithm is nonlinear?

https://iopscience.iop.org/article/10.1088/1742-6596/978/1/012116/pdf Each operation performs a nonlinear function on three of a, b, c,and d. ...
cuthead's user avatar
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177 views

Recreate RC4 Stream cipher

I'm trying to learn how to go about cracking RC4 ciphers (nothing illegal, its an old, i.e., not active challenge for a job application, so no cheating). I have nine md5 hashes with their own ciphers. ...
Richard's user avatar
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3 answers
557 views

If you have two inputs of the same length, are there theoretically collissions in both MD5 and SHA-256?

Can there be two messages M, M' both of the same length such that both MD5(M)=MD5(M') and SHA-256(M)=SHA-256(M')? Let's compare two files: if they have the same length, they are candidates for having ...
Juan's user avatar
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1 vote
1 answer
261 views

Can we build two messages with same MD5 but different size? [duplicate]

Can we build two messages with same MD5 but different size? I researched MD5 collisions, but everything I found targets messages of the same size.
Raoul Bhatia's user avatar
1 vote
1 answer
396 views

Attack MD5 with limited input and partial information

If I know that MD5 input is limited to a character set. can I find any information on the input based on the output? example: input consists of 16 character from list of [1,2,3,4,5]. question: based ...
Mojtaba's user avatar
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0 votes
1 answer
111 views

Will repeatedly applying a hash function to the prior result visit all possible hashes? [duplicate]

If one were to take a message, say "Hello world!", and compute the MD5 hash: 86fb269d190d2c85f6e0468ceca42a20 Then, taking the MD5 hash of this, and repeating that procedure: ...
user192361237's user avatar
2 votes
1 answer
485 views

How are SHACAL-2 ciphers calculated?

I am trying to learn about the underlying functionality of the different hash functions (currently SHA) and I'm pretty stuck even after watching a Stanford video about it. One method of hashing is by ...
Lukas Mittun Alexander Guldstv's user avatar
5 votes
0 answers
78 views

Security implications of using the low-order bits for Merkle–Damgård message length

According to RFC 1321 § 3.2 (MD5), the length of the message ($b$) is encoded as $b \bmod 2^{64}$: ...
forest's user avatar
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0 answers
33 views

Can I clone MD5 hash to a different file? [duplicate]

one.ttf (3f67f2feb32a72cf4b90c767eb43aa52) two.ttf (8880bae64dc9e6ba22446f789d09d3d7) I want to set one.ttf md5 hash to two.ttf It is possible? Like this one.ttf (3f67f2feb32a72cf4b90c767eb43aa52) two....
Khun Htetz Naing's user avatar
1 vote
0 answers
121 views

Changing a bit in IV of MD5

It is obvious that changing even one bit in data or IV (initialization vector) will change the hash value a lot. I want to know if, for example, changing a single bit within the $IV$ in MD5 can be ...
abbas's user avatar
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-5 votes
2 answers
321 views

Are the common hash algorithms already dead? [closed]

I have one honestly question: How can we are so confident with the use of the common hash algorithms (nowadays there are so many pages with cracking tools: crackstation, gpuhash, etc) ? Are we lost ...
Jorge Alberto Medina Rosas's user avatar
1 vote
1 answer
542 views

Is this password-cracking challenge possible?

Taking a graduate computer security class, part of our current assignment is to crack 50 Unix md5crypt password hashes, due on Thursday, October 8th (in eight days.) I've managed to crack 49 out of ...
A. Vance's user avatar
1 vote
1 answer
216 views

Is the MD5 algorithm only useful for bytes, rather than bits?

The MD5 algorithm is designed to accept a message of any length and produce a 512-bit message digest. Because of the way it pads the original message, by adding a 1-bit then a number of 0-bits, the ...
AkThao's user avatar
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1 vote
1 answer
430 views

Avoiding collisions by combining MD5 and SHA-2

It is often suggested that hashing of long character columns can be used for indexing in databases, but the possibility of collisions is an issue for Unique indexes. Whilst I know that both MD5 and ...
user3621075's user avatar
4 votes
2 answers
1k views

The length extension attack and security on length shortening of a hashed message by one byte

MD5, SHA1, SHA2 are vulnerable to length extension attacks Wikipedia:Length extension attack. Could is also be possible to generate $H(\text{message}[1..n-1])$ from $H(\text{message}[1..n])$ if I know ...
Unlikus's user avatar
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3 votes
1 answer
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How can a collision attack using MD5 be used to break WOTS

It is stated in Winternitz One time signature security that MD5 is not safe for Winternitz due to collision attack. Given that WOTS generates multiple, say 32 private keys then hashing them a number ...
evernal's user avatar
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0 answers
154 views

Security implication of concatenating two hashes using different algorithms

Background Hashing files is an expensive thing for CPU. I am tasked to write a secure digital signature scheme. For that, I decided to check the integrity of files using Hash/Digest. To be more secure,...
Eirtaza's user avatar
6 votes
1 answer
116 views

Would increasing the "target space" of MD5 collisions make it significantly easier to find a collision?

This is tangential to this question, which asks about generating a file to match an exact MD5 hash. My question is if it would be significantly easier to generate a file that is "within X digits ...
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