checksum

问题 Previously I asked a question about combining SHA1+MD5 but after that I understand calculating SHA1 and then MD5 of a lagrge file is not that faster than SHA256. In my case a 4.6 GB file takes about 10 mins with the default implementation SHA256 with (C# MONO) in a Linux system. public static string GetChecksum(string file) { using (FileStream stream = File.OpenRead(file)) { var sha = new SHA256Managed(); byte[] checksum = sha.ComputeHash(stream); return BitConverter.ToString(checksum)

问题 I want to integrate Paytm SDK in my app. I have MerchantId and Merchant key . But i don't have those Urls. How to generate those URLS? 回答1: I integrated PayTM sdk into swift application and its working fine . The issue where i got stuck about 15 days is the URL Generation : checkSumGenerationURL and checkSumValidationURL . Earlier i was using PayTM provided url but due to this it gets failed every time trying to payment . so here is the final solution : I sit with my server team and then

问题 How can I generate a CRC-8 checksum in PHP? 回答1: function crcnifull ($dato, $byte) { static $PolyFull=0x8c; for ($i=0; $i<8; $i++) { $x=$byte&1; $byte>>=1; if ($dato&1) $byte|=0x80; if ($x) $byte^=$PolyFull; $dato>>=1; } return $byte; } function crc8 (array $ar,$n=false) { if ($n===false) $n=count($ar); $crcbyte=0; for ($i=0; $i<$n; $i++) $crcbyte=crcnifull($ar[$i], $crcbyte); return $crcbyte; } To use this function for a binary string you have to convert the binary string to an array first.

问题 I'm working on an application where users have to make a call and type a verification number with the keypad of their phone. I would like to be able to detect if the number they type is correct or not. The phone system does not have access to a list of valid numbers, but instead, it will validate the number against an algorithm (like a credit card number). Here are some of the requirements : It must be difficult to type a valid random code It must be difficult to have a valid code if I make a

问题 I am looking for a way to connect to a remote server with ftp or lftp and make sure the following steps: Copy files from FTP server to my local machine. Check if the downloaded files are fine (i.e. md5checksum). If the download was fine then delete the downloaded files from the FTP server. This routine will be executed each day from my local machine. What would be the best option to do this? Is there a tool that makes abstraction of all the 3 steps ? I am running Linux on both client and

问题 I'm using the chechsum function in sql server 2008 R2 and I would like to get the same int values in a C# app. Is there any equivalent method in c# that returns the values like the sql checksum function? Thanx 回答1: CHECKSUM docs don't disclose how it computes the hash. If you want a hash you can use in T-SQL and C#, pick from the algorithms supported in HashBytes 回答2: On SQL Server Forum, at this page, it's stated: The built-in CHECKUM function in SQL Server is built on a series of 4 bit left

问题 I am using following code to implement Luhn algorithm for credit card check in c# language but could not get the output to generate the check sum its showing validity: kindly help me.Thank you in advance public class Program { private static void Main(string[]creditcard) { int sum = 0, d; string num ="7992739871"; int a = 0; for (int i = num.Length - 2; i >= 0; i--) { d = Convert.ToInt32(num.Substring(i, 1)); if (a % 2 == 0) d = d * 2; if (d > 9) d -= 9; sum += d; a++; } if ((10 - (sum % 10)

问题 Let's assume that I have some packets with a 16-bit checksum at the end. I would like to guess which checksum algorithm is used. For a start, from dump data I can see that one byte change in the packet's payload totally changes the checksum, so I can assume that it isn't some kind of simple XOR or sum. Then I tried several variations of CRC16, but without much luck. This question might be more biased towards cryptography, but I'm really interested in any easy to understand statistical tools

问题 I'm looking for a solution to generate a checksum for any type of Java object, which remains the same for every execution of an application that produces the same object. I tried it with Object.hashCode(), but the api says ....This integer need not remain consistent from one execution of an application to another execution of the same application. 回答1: I had similar problem (generating good hashcode for XML files) and I found out that the best solution is to use MD5 through MessageDigest or

问题 My understanding is that a hash code and checksum are similar things - a numeric value, computed for a block of data, that is relatively unique. i.e. The probability of two blocks of data yielding the same numeric hash/checksum value is low enough that it can be ignored for the purposes of the application. So do we have two words for the same thing, or are there important differences between hash codes and checksums? 回答1: I would say that a checksum is necessarily a hashcode. However, not all