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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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. ...
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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 ...
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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.
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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 ...
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Create a MD5 collision on two given files with an identical prefix

I'm stuck on an assignment of mine and maybe someone has some advice for me. I have the following task: I have to modify two files, which differ in exactly one byte, so that they have the same MD5 ...
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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: ...
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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 ...
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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 $b \bmod 2^{64}$: ...
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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....
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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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Combining Hashes - NTLM and SHA

i have been recently learning about different types of hashing and the encryption/decryption methods of such hashes. Im currently trying to find the preimage of this hash i have been given as a ...
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If two hosts are using a transparent IP level authentication and encryption, is their communication subject to both MITM or replay attacks?

Encryption process for any outgoing packet to the specified "remote IP": -original payload P is encrypted (the bytes after the IP header) using RC4 with the preestablished key ...
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Length extension attack in the middle help!

is it possible to insert the command that you want to execute in the middle of the md5 hash token already known?
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How to create two partly similar plaintexts with same MD5 hash value?

The problem I'd like to solve looks like this: There are two plaintexts which differ in length and letters, but contain a few common strings. The first few words and the last few words are the same, ...
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How is the MD5 digest calculated in BGP?

The RFC is very superficial on the implementation details. What is the injective function being used? RFC (ietf) MD5 digest is produced by applying the MD5 algorithm to these items in the following ...
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MD5 hash: retrieve an element of a source string

Suppose you have a string, precisely an MD5 hash string, which basically it is computed in the following way: "element1:element2:element3" So, in order to get ...
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Formula of function in MD5 algorithm

As i read MD5 have many complex formulas, example: $k_i := \lfloor \space| \sin(i + 1) \times 2^{32}| \space\rfloor$ My question is why use sin(), how about cos() or tan() or something like that. ...
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What is the use of encoding a hash output?

In many applications, the MD5 algorithm is used which produces a 128-bit output which is represented as a sequence of 32 hexadecimal digits. This output is further encoded using a base62 or base64 ...
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CHAP vs EAP-MD5

I started studying EAP authentication framework and I don't understand why was the EAP-MD5 developed. Why not just use the CHAP protocol ? To me they seem the same. Can you explain to me ?
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Can the OpenSSL random number generator be considered cryptographically secure? [duplicate]

The OpenSSL Random Number generator documented here uses an OS-provided entropy source coupled with a MD5 hash function. Does it impact the quality of randomness to use a broken cryptographic hash ...
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Storing email addresses in plain sight

What would be the best approach for storing a list of hardcoded email addresses in plain sight (in a public JS file or such)? The site is pretty low-key, for a small community of friends. Starting ...
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Most efficient way to break md5?

if you know the result of a hash, for this example the resulting hash is: ec664d1d65fd8a58c59b337b11c37a4d And you also know the hash has been made like this: <...
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Are there two known ASCII-only strings which have the same MD5 hash value?

Up to now, the pairs of strings that create an MD5 collision that have been discovered all contain non-ASCII (binary) characters. Are there two known ASCII-only strings which have the same MD5 hash ...
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Is it feasible to get a hash collision for CRC32, MD-5 and SHA-1 on one file?

I'm aware that individually, each has its weaknesses (especially CRC32), but is it feasible that a file could be created to falsely match all three?
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Does a hash function have a Upper bound on input length?

I came across this Answer stating (just a line from the answer):- The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash And in the ...
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For a hashing function like MD5, how similar can two plaintext strings be and still generate the same hash?

When I say similar, I'm referring to the Hamming distance, the Levenshtein distance, or a similar string distance metric that measures how similar or dissimilar two strings are. For instance, are ...
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Suitable 16-bit checksum?

I am writing a toy1 transport protocol and I am trying to implement a feature whereby: A 16-bit checksum is included in every packet. This checksum can be extended to be 48-bit if the data is large, ...
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Does it matter if I publish only publish good or bad MD5 hashes after recovering from a hack?

(This question is a follow-up from another question I asked about MD5, which is why I'm insisting on using MD5 in this question as well) My imaginary Linux distribution, Sushi Linux has had a big ...
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Is there really no use for MD5 anymore?

I read an article about password schemes that makes two seemingly conflicting claims: MD5 is broken; it’s too slow to use as a general purpose hash; etc The problem is that MD5 is fast I know that ...
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Is OpenSSL HMAC vulnerable to length extesion attacks when using MD5 as hash algorithm?

Given that a valid hash for a specific payload is known, would some C code like this be vulnerable to a length extension attack? ...
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Overcome MD5-RSA Signature verification

I asked this question already at the Information Security SO site, but my research on how to overcome this problem ended always on the crypto site. That's why I will try to find some help here :) I ...
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MD5: Existence of invariant (fixed point)

Is it possible to find 128 bits $B$ such that $md5(B) = B$? md5 has collisions that can be computed in acceptable time, but I did not find any papers on fixed points in md5. As pointed out in this ...
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How does MD5 divide the padded message in 16 words?

This is the image from a website that shows all the steps of the MD5 Hashing algorithm: The original message is 'Hello World!'. I don't understand where these values are coming from: For example the ...
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How did I get a nonuniform distribution of UUID4s across MD5 space?

We have a system that processes data. Each entity has an ID that is generated using uuid4() in Python. Later, that ID is used as a partition key for AWS Kinesis. ...
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Integrity check of a binary firmware file with hash function

I need to provide a mechanism that it is possible to verify the integrity of a firmware image flashed on an embedded system. The procedure should be, that if someone has doubt on the firmware’s ...
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Add string to create specific MD5?

I have a file that include a long string , I can calc the md5 of this file . Is there any way to know which string I need to add for this file so the md5 of this file will be specific md5 that I want?...
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Using a hash function as a random number generator

Using MD5 or SHA1 for instance, and applying integers (as seed so to speak) to the hash function, in sequence, and only keeping, say, the first 64 bits of the resulting hash, do we always have a ...
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What is the smallest last value of sequence of integers from 1, where there is a collision in md5? [duplicate]

Question is just out of interest. If we take md5 hash from all integers from 1 to n, what is the first n, where its md5 collides with some previous md5? Has anyone ever calculated and proved the ...
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Md5 padding bits

What is the condition if the message size in md5 increses from 448 as the 64 bits are the length and we have to make the block of 512. So what will be the bits if it increases from 448
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Practical attack on md5 hashing algorithm?

I have the following conditions: String which consist of "STRING+key+ID+key" is hashed with md5. I have a knowledge of STRING (10 chars), ID is probabilistic (int 15), key is 15 chars long (a-z A-Z 0-...
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Vulnerabilities of AES method that uses MD5 to create the key

Are there security vulnerabilities given the would a user be able to access the original text and the encrypted text with AES using an MD5 as a key? In other words, if the user had both the original ...
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MD5 - Chosen Prefix Collision Attack

Given 2 messages $m_1$ and $m_2$, in a chosen prefix attack, we want to find $s_1$ and $s_2$ such that: $\text{MD5}(m_1 || s_1) = \text{MD5}(m_2 || s_2)$ Are $s_1$ and $s_2$ found by brute force ...

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