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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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 ...
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68 views

Is it possible to crack any MD5 hash? [on hold]

I really wonder is it possible to crack any MD5 hash?
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99 views

Thoughts on secure hashing and the “mds” algorithm

Almost a decade ago Raymond Chen blogged [1] about the "hash reset attack" cautioning developers to record the content length in addition to the message digest. Recently I came up with a variation on ...
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78 views

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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2answers
185 views

Is Dropbox's hashing method cryptographically secure?

Dropbox uses CRC32 and md5 to create a checksum of each 4 mb "block" as part of the their compression/file system. I suspect that Dropbox uses an additional cryptographic hash to check if there's a ...
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119 views

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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2answers
490 views

Strength of MD5 in finding duplicate files

Why there is a lot of duplicate file finder application are using MD5 Algorithm? What is the strength of MD5 in terms of searching duplicate files in hard disk or flash driver or any other storage ...
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0answers
35 views

TCR hash functions from MD5

I'm reading Collision-Resistant Hashing: Towards Making UOWHFs Practical (pag. 10 and 11) and here say The most direct way to construct a TCR hash function is to key a function like MD5 or SHA-1. ...
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2answers
81 views

MD5 theoretical question

Ok, so this is a very possible stupid question, but one of those things that has sat at the back of my mind for a while. We all know that MD5 has issues, and these have been known for about a decade. ...
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1answer
507 views

Does ssl_rsa_with_rc4_128_md5 have known weaknesses?

My bank's website uses HTTPS with the cipher suite ssl_rsa_with_rc4_128_md5. What are the known weaknesses of this suite? Do they have a practical impact for ...
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0answers
163 views

Question about modifying the MD5 plain text to cause a collision

I was trying to understand MD5 and got stuck with this question, its from Michael sipser's book on Information security Principles and Practice, 2nd edition The MD5 collision in Problem 25 is said ...
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1answer
98 views

md5sum collision question

I've been reading the wikipedia page, trying to get a better understanding of how to produce a collision. http://en.wikipedia.org/wiki/MD5#Collision_vulnerabilities The wikipedia page above states: ...
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182 views

What is the relation between hash chaining and chosen prefix attack

I read that hash chaining can be used to prevent hash collisions, while the chosen prefix attack allows hash collisions for algorithms like MD5. How are they related? Does hash chaining prevent the ...
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1answer
112 views

salting with password hash to improve security?

Would something like the following improve security (against rainbow attacks, not brute force)? Assume that $P$ is a user-chosen password, and the objective is to obtain a hash $H$ for password ...
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1answer
126 views

Has it become easier to pre-compute tables after MD5 collisions?

Apparently it is not possible to compute all MD5 values from 0x00000000000000000000000000000000 to ...
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1answer
188 views

why hash(hash(str)) is bad?

Why do people say that using hash twice or more is bad? yes there is key derivation that do that job, but in a low bandwidth network countries, the solution i see is to use a simple hashing system on ...
5
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1answer
649 views

Is HMAC-MD5 considered secure?

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 ...
2
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1answer
311 views

length extension attack on an MD5 hash of a text file of about 10K Bytes?

How much computing time on a typical desktop computer would it take to find a new length and new data to extend a text file of about 10K Bytes with a given MD5 hash?
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381 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?
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625 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
163 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
880 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 ...
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1answer
518 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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3answers
590 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 ...
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724 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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144 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 ...
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168 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 ...
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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 ...
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1answer
182 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 ...
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212 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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246 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 ...
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243 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 ...
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1answer
108 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: ...
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2answers
242 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 ...
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810 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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242 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 ...
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1k views

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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428 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 ...
5
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290 views

Tunnels used in md5

I'm reading the paper "Message Freedom in MD4 and MD5 Collisions: Application to APOP" about finding collisions for the MD5 hash algorithm involving the concept of tunnels as described in "Tunnels in ...
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2answers
165 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 ...
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3answers
457 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. ...
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1k 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 ...
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756 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
412 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, ...
2
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1answer
436 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. ...
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257 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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541 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
7k 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 MD5 hash value (representing a so-called "MD5 collision")?
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3answers
1k 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 ...
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774 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: ...