Hi everyone I have a script where I have to download some files and to make sure that everything worked fine I'm comparing MD5 checksums. I have found that the checksums are not correct when downloading with CURL. The script below demonstrates this. It downloads the Google logo and compares checksums. $url = 'http://www.google.com/in...
Lets say I have a class A that inherits from class B in C#. Class B has a property on it called Checksum which, when called at runtime, is to calculate the checksum of all the properties on an instance of class A (the particualr checksum algorithm used is not important, one from the BCL probably). Importantly, the checksum algorithm mus...
I want to create a shellscript that reads files from a .diz file, where information about various source files are stored, that are needed to compile a certain piece of software (imagemagick in this case). i am using Mac OSX Leopard 10.5 for this examples. Basically i want to have an easy way to maintain these .diz files that hold the ...
Is there a file upload control for ASP.Net which performs a client-side checksum calculation (CRC, MD5, etc) on the file contents and transmits the checksum to allow for server-side checksum validation? I have looked through answers on several file upload questions, but did not find this feature mentioned anywhere. ...
Hi, I need to implement the MD5 checksum to verify a MD5 checksum in a XML file including all XML tags and which has received from our client. The length of the received MD5 checksum is 32 byte hexadecimal digits. We need set MD5 Checksum field should be 0 in received XML file prior to checksum calculation and we have to indepandantly...
Does anyone know the formal / official name of the checksum algorithm used in the following functions? function Checksum($number, $encode = true) { if ($encode === true) { $result = 0; $number = str_split($number, 1); foreach ($number as $value) { $result = ($result + ord($value) - ...
I need to embed images inside OpenOffice Text documents without the help of OpenOffice itself. For that I need to work directly inside the zip archive and modify the appropriate xml files. The problem I have now is that OpenOffice stores embedded pictures inside a picture folder and asigns a unique name to them according to the informati...
Interestingly, I can find implementations for the Internet Checksum in almost every language except C#. Does anyone have an implementation to share? Remember, the internet protocol specifies that: "The checksum field is the 16 bit one's complement of the one's complement sum of all 16 bit words in the header. For purposes of c...
Hi all, I have a clarification regarding Checksum of files. In my test application, I got the same checksum value for a duplicated file of my original file. Also, when my original file was renamed, the checksum generated was same. So, can I use the checksum to discard the processing of a duplicated file or a re-named file. regards, K...
Are there algorithms for putting a digest into the file being digested? In otherwords, are there algorithms or libraries, or is it even possible to have a hash/digest of a file contained in the file being hashed/digested. This would be handy for obvious reasons, such as built in digests of ISOs. I've tried googling things like "MD5 inje...
When calculating a single MD5 checksum on a large file, what technique is generally used to combine the various MD5 values into a single value? Do you just add them together? I'm not really interested in any particular language, library or API which will do this; rather I'm just interested in the technique behind it. Can someone expla...
Hi, I need to convert the following c code (to calculate checksum for a file) to python. I had written, the corresponding code in python but the result didn't match the c version. The problem was that python autmatically promotes int to long whenever overflow occurs and this results in wrong checksums. Any idea how to overcome this pro...
how can i create a checksum of only the media data without the metadata to get a stable identification for a media file. preferably an cross platform approach with a library that has support for many formats. e.g. vlc, ffmpeg or mplayer. (media files should be audio and video in common formats, images would be nice to have too) ...
I am sending objects to a server in java, however I want to ensure that it has not been tampered with, in addition to the already provided security. I understand how to take do use a message digest, however, should the checksum ideally be placed in the object? and if so wouldnt this change the checksum at the end. How do you go about thi...
Is there a program, or a script out there that can compare the md5 checksum of files I tried to create my own, but i'm having problems with any files that have a space in them, so I was wondering if it'd be easier to just use an application. md5deep is something I downloaded that returns the checksum. rm md5mastervalue for i in `ls /me...
Hello, I am trying to manually change my paper-toss highscore for my ipod touch. I have gotten into the filesystem and seem to have found the file where the highscores are held. I change the value but the only problem is, is when i go back into the game all highscores are reset. I figure it is because of the checksum in the code. I do no...
I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. ...
Given two different strings S1 and S2 (S1 != S2) is it possible that: SHA1(S1) == SHA1(S2) is True? If yes - with what probability? If not - why not? Is there a upper bound on the length of a input string, for which probably of getting duplicates is 0? OR is the calculation of SHA1 (hence probability of duplicates) independent o...
i am using raw sockets to create my own socket. i need to set the tcp_checksum. i have tried a lot of references but all are not working (i am using wireshark for testing). could you help me please. by the way, i read somewhere that if you set tcp_checksum=0. then the hardware will calculate the checksum automatically for you. is this tr...
I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are t...