MD5 is a hash function that is no longer considered secure. It should only be used for backward compatibility.
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2answers
81 views
Generate fixed length cipher text from arbitrary length plaintext
Using an encryption algorithm like AES, is it possible to generate a fixed length cipher text no matter how long the plain text becomes?
3
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1answer
112 views
Using an MD5 hash as a password
Suppose Alice is using a password prompt that only accepts up to 32 characters for any particular password.
Memorization of long strings of random characters is not one of Alice's strengths, so she ...
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3answers
86 views
Padding of Original Message in MD5
what should I do if my original message is greater than 64 bits? what is the process of padding in MD5?
As described in Internet Security: Cryptographic Principles, Algorithms and Protocols, page ...
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2answers
212 views
Even 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 ...
3
votes
1answer
104 views
BCrypt vs Key Stretching MD5
Ars technica posted an article about the latest in cyber warfare from the stuxnet crew.
They key stretched MD5 by iterating it 10,000 times. It seems to be effective at handicapping HashCat's gpu ...
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votes
3answers
448 views
Is this encryption algorithm build from MD5 secure?
I'm being asked to use an encryption algorithm in my code, and besides the fact that I'm sure there will be implementation faults that lead to vulnerabilities, I also have concerns about the algorithm ...
6
votes
1answer
168 views
Can I find two specific words with the same md5 hash?
I want to find two strings containing special words like "yes" or "no", mixed with random characters, for which the MD5 hash is equal.
An example of what I'm looking for:
...
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0answers
67 views
MD5 > Would multiple hashings increase security? [closed]
A Simple question,
if i run a string trough the standard md5 encryption function multiple times, does it increase security the more i do it? does it protect against rainbow tables? etc.
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1answer
86 views
MD5 implementation
As a personal project, I want to implement MD5 on an FPGA, but I have some doubts about the specifics of the implementation.
My first source of how the algorithm is implemented was the RFC 1321, where ...
2
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0answers
122 views
Creating colliding x509 certificates: Crafting RSA moduli step
I am trying to generate 2 x509 certificates with the same signature but different values in the common name field, based on md5 collisions, as it was specified in this paper (page 7).
Now I have ...
1
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0answers
31 views
Will length-extension work if secret is not prefixed but appended to the data? [duplicate]
Possible Duplicate:
Why is h(m||k) insecure?
Length-extension allows to append any data to the message while not knowing the secret. Any length-extension explaination one the web considers ...
2
votes
1answer
105 views
A question regarding relevance of vulnerability of MD5 when linking multiple records together
I have been studying a Supreme Court case "IMS Health vs Sorrel".
In this case a Friend of Court brief filled by "Electronic Privacy Information Center" states that use of MD5 hash function to link ...
1
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2answers
122 views
Speeding up partially known plaintext preimage recovery attack on MD5
Suppose there are three messages A, B and C of different length, that are 16 DWORDs in ...
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2answers
153 views
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 ...
2
votes
1answer
139 views
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 ...
0
votes
1answer
89 views
MD5 pre-fixing with an unkown postfix
Is the MD5 prefixing attack still valuable to an attacker if he doesn't know the postfix of the string?
For instance, what if the following sanity check was being used:
...
4
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2answers
187 views
Do MD5's weaknesses affect Oplop?
Oplop is an algorithm that generates account-specific passwords from a master password and user-chosen nickname (typically username@domain). From the website:
Concatenate the master password with ...
4
votes
1answer
361 views
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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votes
3answers
209 views
Should I use md5 for my new application?
MD5 is a very fast hash and its output is short and easy to store. Should I use it for my non-security-sensitive application?
I don't think so, but I can't seem to convince anyone else that this is ...
2
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1answer
242 views
Partial collisions for md5
Let $h$ be a bitstring and let $P(h, n)$ be the n-bit prefix of $h$. A partial collision of length $n$, for a hash function $H$ is a pair $(x,y)$, such that $P(H(x),n)=P(H(y),n)$.
What is known about ...
4
votes
2answers
202 views
Tunnels used in md5
I'm reading a paper about finding collisions for the MD5 hash algorithm involving the concept of tunnels.
But I couldn't understand about the difference between point of verification and point of ...
2
votes
2answers
139 views
MD5 implementation doubt
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 ...
5
votes
3answers
344 views
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. ...
4
votes
2answers
548 views
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 ...
2
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0answers
528 views
MD5 encryption in Windows batch script [closed]
I am making a script in Windows batch to have a registration and login system that stores the passwords in a SQL database using SQLite. I need a command line MD5 encryption program to encrypt the ...
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3answers
293 views
reverse of 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,
...
1
vote
1answer
254 views
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. ...
4
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2answers
213 views
Cost of attacking Mobile OTP with a fake server
You want to obtain a 74-bit secret $K$. There is an oracle that will provide you with the following value for several values of $T$:
...
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2answers
324 views
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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5answers
2k views
Are there two known strings which have the same MD5 hash value?
Is there an example of two known strings which have the same hash (MD5) value, i.e. an MD5 collision?
9
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3answers
544 views
Why does the padding in MD5 contain the message length?
I understand the need for padding in MD5. But why do we append the message length to the padding?
I heard it strengthens the hash but how?
Please provide an example if possible and how it applies to ...
3
votes
2answers
462 views
Is it a good idea to use bitwise XOR on a set of MD5 sums?
I have designed an SQL aggregate function in Oracle that bitwise XORs all MD5 sums of the values stored in a column.
For example, if my table is:
...
13
votes
4answers
6k views
Best way to reduce chance of hash collisions: Multiple hashes, or larger hash?
I would like to maintain a list of unique data blocks (up to 1MiB in size), using the SHA-256 hash of the block as the key in the index. Obviously there is a chance of hash collisions, so what is the ...
3
votes
1answer
161 views
Is the last step of an iterated cryptographic hash still as resistant to preimage attacks as the original hash?
Considering a cryptographic hash, such as MD5 or SHA2, denoted by the function $H(m)$ where $m$ is an arbitrary binary string, there is a lot of material available that deals with potential weakness ...
6
votes
1answer
436 views
Implementation of Tao Xie and Denguo Feng's MD5 attack
It is well known that MD5 is completely broken today - however, to understand the theory behind the attacks I am looking for an implementation of the collision attacks described in the 2009 paper A ...
5
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4answers
286 views
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?
7
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1answer
365 views
Change in probability of collision when removing digits from MD5 hexadecimal hash values
I am aware that MD5 has a known collision vulnerability and should not be relied upon when uniqueness is required, but in the environment I am working on I only have access to MD5 hash function. ...
