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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Why does the padding in Merkle–Damgård hash functions like MD5 contain the message length?
I understand the need for padding in MD5 and other hash algorithms such as SHA-1, SHA-256, SHA-384 and SHA-512. But why do we append the message length to the padding? I heard it strengthens the hash ...
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Are there two known strings which have the same MD5 hash value?
Is there an example of two known strings which have the same MD5 hash value (representing a so-called "MD5 collision")?
Adban
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Is HMAC-MD5 considered secure for authenticating encrypted data?
I've read something to the effect that the HMAC construct is able to lessen the problem of collisions in the underlying hash.
Does that mean that something like HMAC-MD5 still might be considered ...
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Could we break MD5 entirely in the future?
Even of today MD5 is (sadly) still heavily used in some applications. Even big tools like ApacheMD5. But even today there are more then enough MD5 hashes which are still not cracked.
According to ...
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How hard is it to generate a simultaneous MD5 and SHA1 collision?
I was recently reading that MD5 is "broken" because it's pretty easy to generate collisions (like 2^(L/2)). And the SHA1 (theoretically) fares no better. The ...
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Is a second preimage attack on MD5 feasible?
What's the practical status of MD5 w.r.t. second-preimage?
Integrity of a piece of data is protected by an MD5 hash, itself assumed genuine. The data (and thus the hash) is known to the adversary. ...
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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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How many trials does it take to break HMAC-MD5?
I know that you can find collision in MD5 with $2^{64}$ trials using Birthday paradox. Now everyone is saying that HMAC-MD5 is significantly more secure. How can I quantify this security? My question ...
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What is the MD5 collision with the smallest input values?
I am interested in MD5 collisions for small input messages.
The collision examples given at http://www.mscs.dal.ca/~selinger/md5collision/ show two different strings, where only a tiny amount of data ...
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Are there MD5 collisions for inputs of different length?
There are many examples of MD5 collisions (some of them can be found here Are there two known strings which have the same MD5 hash value?). But as far as I know two inputs should have the same length ...
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What is the recommended replacement for MD5?
Since MD5 is broken for purposes of security, what hash should I be using now for secure applications?
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Is HMAC-MD5 still secure for commitment or other common uses?
MD5 collisions have been out for some time. In spite of this, HMAC-MD5 is still secure for authenticating data1. This illustrates a strength of the HMAC construction, it does not require that the hash ...
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What was the first MD5 collision ever constructed?
We all know that MD5's collision resistance is severly broken.
But when thinking of "random" strings with great cryptographic importance I've come up with NIST's curve seeds and MD5 collisions. But ...
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Pre-image attack on MD5 hash
I read somewhere MD5 is broken in terms of collision, but I am wondering if it is broken in terms of pre-image resistance?
Given a hash of Md5, is it possible to find the original message of it? If ...
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Will hashing over and over eventually give the same hash?
There are many cases in maths where doing the same thing over and over again will bring you closer to a value. Derivation of polynomials is the striking example: no matter what you start with, you end ...
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Computing the padding of MD5
So I'm reading this question to learn more about length extension attack, and I want to make sure I understand the basics of padding.
It says in the post that given the hash and the length of the ...
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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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How does the attack on MD5 work that allows a file to show its own (full) hash?
I've recently stumbled across this "moment" on Twitter, where there are three files, that show their own MD5 hashes.
As an example, this GIF (screen-shotted in the following image), has the hash:
<...
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How were shift amount constants in MD5 found?
The md5 specification gives a series of 4 rounds to execute over a 16-word block.
Each round has a repeating sequence of 4 shift amounts (s in ...
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Is MD5 second-preimage resistant when used only on FIXED length messages?
I fully realize that MD5 should not be used in any new project, but in my particular situation I have severe CPU performance issues, so MD5 is convenient.
I have read a lot about MD5 security for this ...
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Why aren't hash values for "nothing" (empty) defined as all zeros?
Any decent hash algorithm will produce basically "random like" values for any given input including the empty input.
For example MD5 produces d41d8cd98f00b204e9800998ecf8427e on an empty input.
I ...
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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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Does MD5 generate 128 independent bits?
I heard that there are 128 stochastically independent bits in an MD5 output. Is that true?
If so, are there any citations or proofs for that?
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md5: is reverse length-extension attack possible?
If I know
H = md5( SECRET_KEY | DATA )
then I can calculate
H' = md5( SECRET_KEY | DATA | DATA' )
That's length-extension ...
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MD5 Hash outputs not produced
Are there any hash outputs not produced by the MD5 hash function? I need to use it as a placeholder for an empty hash while comparing two hashes.
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Is it computationaly feasible to reverse MD5SUM?
This might be out of ignorance, I apologize, but how complex of a problem might it be to generate a file of size $N$ whose MD5SUM is $X$?
For example,
...
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1024 RSA Hash Signature attack. Forge a valid signature
I have an RSA signature of 1024 bit where i know the following:
Public modulus N
Public exponent (0x03)
Cypher message
Summary:
An MD5 hash is calculated from a collection of byte and is used as ...
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Cracking secret key of a MD5 hash?
I have a MD5 hash which is obtained by hashing certain strings appended by a pipe character ( | ). (I know the values of these) A secret key is added as a suffix to this (I don't know the secret key). ...
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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 ...
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How can hashes be unique if they are limited in number? [duplicate]
I'm curious, how can for example SHA-256 be unique if there are only a limited number of them?!
For clarification:
how many MD5 hashes are there?
$16^{32}$ MD5 hashes can be produced.
$16^{64}$ SHA-...
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How are the functions used in cryptographic hash functions chosen?
I'm learning about cryptographic hash functions and I have some questions about the functions used in the compression function.
MD5 uses the following functions:
$f_{1}(B,C,D)=(B\wedge C)\lor(D\...
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128 bit hash with least chance of collision?
I'm building a storage system for JSON documents where they are looked up on a 128 bit key. These JSON documents have a timestamp within them, but apart from that are user-entered data. These JSON ...
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How to authenticate over open channel?
I am making an arduino project to open my garage door. I want to make it so users with the passphrase can open the door. Due to computational restrictions it is unlikely encryption is possible. ...
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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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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 does "bits" mean in the context of hash functions?
What does the "bits" in hash functions mean?
I started studying hash functions but I still do not understand what the bits mean.
What does it mean to say that MD5 is 128-bits or that SHA-1 is 160 ...
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Passwords are vulnerable to hash collision attacks?
As stated in this page large documents hashed using md5 maybe vulnerable to collision attacks. My question is even passwords of 6-30 character are vulnerable to such hash collision attacks? If yes, is ...
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Addition step in MD5 implementation
In MD5, there are four rounds. After every round, why do we need to add the computed $Q$ values to the initial values and then take this value as input to the next round. For example after the first ...
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Is it possible to demonstrate that md5(x) != x for any x?
I am looking for an easy to follow explanation, if possible, that demonstrates/proves the validity (or not!) of this assertion:
for any X, md5(X) != X (being X any string of 32 hex characters)
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To understand a fact related to padding in MD5
I'm trying to understand the padding process of MD5
from this link.
In that paper in Section 3.1, I found the following description of padding:
The message is "padded" (extended) so that ...
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Is HMAC-MD5 collision-resistant if the key is unknown?
I'm in a situation where I need to use HMAC-MD5 (for a learning, non-production application) and it needs to be collision-resistant.
So my question: Is HMAC-MD5 collision-resistant if the key is ...
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Finding partial pre-image of MD5 hash
I have the following requirement for hashing using MD5.
H(A,B,C,X);
Where values A,B & C are given. However X is not given.
I would like to find out what value of X would give a hash beginning ...
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Is there any relation between two strings with the same MD5 hash?
Is there any relation between two strings with the same MD5 hash?
For example these two strings:
...
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HASH Algorithm for 8 bits MCU
I need to implement the HASH algorithm (MD5 & SHA-1) on an 8 bit MCU. I hear it can only be implemented on 32bit and sometimes 16bits MCU. Is that possible? I will appreciate link where possible. ...
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Can md5 be used for encrypting data?
I know that md5 shouldn't be used for password hashing because of collisions and possibility of making dictionary attacks e.g. using rainbow tables. But what about ...
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Determine safety of exercise hash functions [duplicate]
There have been several attacks against hash functions such as $h_{sha1}$ and $h_{md5}$.
Professor A suggests a new function $h_{666}$ with an output length of 666 bits.
Professor B suggests ...
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How can one generate pairs/triplets/.../n-ary MD5 collisions
Is there a way to generate n strings with the same MD5 hash?
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distribution for a subset of md5
I need to uniquely assign a 32 bit integer to a collection of human readable strings (i.e. they will not be generated with hash collision in mind). I don't expect more than a few thousand strings. I ...
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What does it mean when two encrypted files, encrypted with the same method but with different keys, when xor'd together, produce a repeating pattern?
Let's say I have fileA and fileB, both encrypted somehow, but in the same method with different keys.
If I xor them together, they will make a repeating pattern of 32 bytes length.
What does that say ...
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Does MD5 hash have quasi commutative property? [duplicate]
I am implementing a one-way accumulator using MD5 hash, wondering wheather it has quasi commutative property or not.
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