crc32

问题 Most of the CRCs I've implemented were appending the calculated CRC value to the message (payload) and checking for a zero result at the receiver after all bytes incl. CRC value were fed through the CRC register. Obviously this is a quite standard approach. Now I would like to use a different approach: Calculate a value from the payload. Use that value as initial value for the CRC register before the message bytes (payload) are fed through the CRC register such that the result after the last

问题 I want to caculate in a tcl script the CRC for this frame : 00000A00080000000A00090000004500002E0000000040117AC00000000000000000003F003F001AB6EB000102030405060708090A0B0C0D0E0F1011 The expected CRC is 0x1652255A. I tried the following (found here): % set string \x00\x00\x0A\x00\x08\x00\x00\x00\x0A\x00\x09\x00\x00\x00\x45\x00\x00\x2E\x00\x00\x00\x00\x40\x11\x7A\xC0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x3F\x00\x3F\x00\x1A\xB6\xEB\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\ x0D\x0E\x0F

问题 I am trying to verify this statement from Wikipedia (http://en.wikipedia.org/wiki/Cyclic_redundancy_check): Sometimes an implementation appends n 0-bits ( n being the size of the CRC) to the bitstream to be checked before the polynomial division occurs. This has the convenience that the remainder of the original bitstream with the check value appended is exactly zero, so the CRC can be checked simply by performing the polynomial division on the received bitstream and comparing the remainder

问题 In some code that I wrote recently, I had this pattern: from zlib import crc32 new_data = get_some_input() crc32List['stream1'] = crc32(new_data, crc32List['stream1']) & 0xffffffffL crc32List['stream2'] = crc32(new_data, crc32List['stream2']) & 0xffffffffL ... crc32List['streamN'] = crc32(new_data, crc32List['streamN']) & 0xffffffffL It seems to me, that there's a bit of redundant computation going on there and if I can find a function called magic(x, y) that does the following caching, I

问题 I'm not good at algorithms like CRC32, MD5 etc. so I'm even having difficulty asking the question :) Basically there is a C# application that uses [DllImport("Crc32.dll")] private static extern UInt32 CRC32Calc(UInt32 crc32, byte[] buffer, uint length); and further down in the code uses it in a method Generate like this UInt32 crc = CRC32Calc(crcSeed, rawData, (uint)rawData.Length); while using a certain crcSeed value. My job is to rework the entire Generate method into a PHP function while

问题 I'm using Python-2.6. I have very little knowledge of hash functions. I want to use a CRC hash function to hash an IP address like '128.0.0.5' into the range [0, H). Currently I'm thinking of doing zlib.crc32('128.0.0.5')%H. Is this okay? There's a few ques. you could try and answer... does it make any diff. if I hash '128.0.0.5' or its binary '0001110101010..' whatever that is or without the '.'s zlib.crc32 returns a signed integer. Does modding (%) a neg. with a positive H always give a pos

问题 I am retrieving lists of crc32 hashes that contain names of files, not there contents. I need to be able to decrypt the strings which are hashed names like "vacationplans_2010.txt" which are less then 25 characters long. is this possible? 回答1: it is one-way hash function. It can't be decrypted. 回答2: Despite what other users answered, CRC32 is not a cryptographic hash function ; it is meant for integrity checks (data checksums). Cryptographic hash functions are often described as "one-way hash

问题 I'm a PHP developer and a little out of my element in C#. In PHP, there's a crc32() function which returns a signed integer for any string that you pass in. So this is what I'm used to: <?php echo crc32("test"); // displays -662733300 I would like to do the same thing in C#. I came across this C# class library but understand little about it. According to his instructions, I'm supposed to do this: // first convert string to byte-array String input = "test"; byte[] bytes = new byte[input.length

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . Is the below code correctly calculating the FCS value of wireless 802.11 frames? Because the value produced by the below code does not match the value shown by wireshark. const uint32_t crctable[] = { 0x00000000L

问题 I'm doing a simple script to check crc of all files... require "zlib" exit if Object.const_defined?(:Ocra) files = Dir.glob("*") File.open('dir.txt', 'a+') do |file| file.puts files end File.read('dir.txt').each_line { |line| file = File.read(line) ; nil file_crc = Zlib.crc32(file,0).to_s(16) puts line, file_crc } The problem is at the line File.read('dir.txt').each_line { |line| I get this error: test.rb:13:in `read': Invalid argument - 1.exe (Errno::EINVAL) from C:/Users/Administrador