Sunday, January 9, 2011

CrazyEngineers Forum

CrazyEngineers Forum

Md5

Posted: 09 Jan 2011 11:22 AM PST

In cryptography, MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check the integrity of files. However, it has been shown that MD5 is not collision resistant;[3] as such, MD5 is not suitable for applications like SSL certificates or digital signatures that rely on this property. An MD5 hash is typically expressed as a 32-digit hexadecimal number.

The security of the MD5 hash function is severely compromised. A collision attack exists that can find collisions within seconds on a computer with a 2.6Ghz Pentium4 processor (complexity of 2^24.1).[17] Further, there is also a chosen-prefix collision attack that can produce a collision for two chosen arbitrarily different inputs within hours, using off-the-shelf computing hardware (complexity 2^39).

MD5 digests have been widely used in the software world to provide some assurance that a transferred file has arrived intact. For example, file servers often provide a pre-computed MD5 (known as Md5sum) checksum for the files, so that a user can compare the checksum of the downloaded file to it. Unix-based operating systems include MD5 sum utilities in their distribution packages, whereas Windows users use third-party applications.

MD5 processes a variable-length message into a fixed-length output of 128 bits. The input message is broken up into chunks of 512-bit blocks (sixteen 32-bit little endian integers); the message is padded so that its length is divisible by 512. The padding works as follows: first a single bit, 1, is appended to the end of the message. This is followed by as many zeros as are required to bring the length of the message up to 64 bits fewer than a multiple of 512. The remaining bits are filled up with a 64-bit integer representing the length of the original message, in bits.

The main MD5 algorithm operates on a 128-bit state, divided into four 32-bit words, denoted A, B, C and D. These are initialized to certain fixed constants. The main algorithm then operates on each 512-bit message block in turn, each block modifying the state. The processing of a message block consists of four similar stages, termed rounds; each round is composed of 16 similar operations based on a non-linear function F, modular addition, and left rotation.

http://upload.wikimedia.org/wikipedi...px-MD5.svg.png

Dividing two numbers

Posted: 09 Jan 2011 08:21 AM PST

You are given two numbers A and B,
You have to divide A by B without using division operator and modulus operator ?

PS: Repeated Subtraction is not allowed..

I have thought of a solution but i am not satisfied with that so asking for help of CEans

c programs list for interview aspect

Posted: 09 Jan 2011 05:36 AM PST

Hai i want c programs list.........

workshops in Andhra pradesh

Posted: 09 Jan 2011 05:31 AM PST

Hai friends
i want to participate in workshops in my state,
any one give my their list
workshops in next month............

Free falling bodies

Posted: 09 Jan 2011 04:05 AM PST

Try to solve this and show your solution.
1. A stone is dropped from a well and 5s later the sound of the splash is heard. If the velocity of sound is 1120ft per second, what is the depth of the well?
2. A stone is dropped from a captive balloon at an elevation of 1000ft. two seconds later another stone is projected upward from a ground with a velocity of 248 ft per second. if the g is 32ft/s, when, where will the stones be at the same level?
Neglect air resistance.

Need help in Java using swing tools

Posted: 08 Jan 2011 11:24 PM PST

How can we build a app that has 4 boxes and on clicking them boxes can be joined to other .
Needd urgently ...
plz help me out

Indian Engineering Entrepreneurship Scenario

Posted: 08 Jan 2011 10:22 PM PST

CEans,

Recently, we made a call to all the student-startups and the companies started by students or fresh graduates. However, the response that we got was very disappointing. It's also very sad to know that most of the Indian Engineering Students are dying to get selected in IT companies.

Of course I don't expect large numbers, but the ratio of student startups / number of fresh graduates is very poor.

What do you think are the reasons and what can CE do the make a difference?

Startups Incubeted In e-Cell Of Your College?

Posted: 08 Jan 2011 10:13 PM PST

CEans,

Why not tell us about the start-ups incubated in your college's e-cell? I see a new trend coming up among engineering colleges to host an entrepreneurship cell and incubate student started companies.

We wish to know about these startups and what are they working on. We'd also like to feature them on CE.

Job Or Startup: How To Decide?

Posted: 08 Jan 2011 10:04 PM PST

There are many engineers who've spent some time in the corporate world who face the dilemma whether they should take the plunge or continue in their job.

There are students as well, who have the same question as well. Whether they should join the corporate world or start their own company.

If you have the dilemma, the answer is very simple: Go for the job.

Why? Because if you have planned well, you won't have that dilemma anymore. Wait for the moment when you'll not be able to sleep well and continue thinking about taking the plunge.

It's that simple. What do you think? Makes sense?

An engineering comic by PHD (Piled High and Deeper)

Posted: 08 Jan 2011 07:37 PM PST



I have experienced this once. :p

Engineering an Empire - The Story of the Byzantine Greeks

Posted: 08 Jan 2011 07:22 PM PST

Rome is known for it's engineering marvels. They defied the laws of nature to build exceptionally breath-taking big structures.

See the story of the Byzantine Empire of the Greeks:

After 10th :- 3 years diploma or+1 ,+2

Posted: 08 Jan 2011 07:19 PM PST

After reading some thread, the thought occurred in my mind of starting this thread. I hope it will help a lot of students

What do you think Guys?

Which one is better among two?
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