checksum

问题 In my app I have a requirement to generate an MD5 checksum for a file. Could you please tell me if there is any way in which this can be achieved? Thank you. 回答1: Convert the file content into string & use the below method: public static String getMD5EncryptedString(String encTarget){ MessageDigest mdEnc = null; try { mdEnc = MessageDigest.getInstance("MD5"); } catch (NoSuchAlgorithmException e) { System.out.println("Exception while encrypting to md5"); e.printStackTrace(); } // Encryption

问题 I have to sync large files across some machines. The files can be up to 6GB in size. The sync will be done manually every few weeks. I cant take the filename into consideration because they can change anytime. My plan is to create checksums on the destination PC and on the source PC and then copy all files with a checksum, which are not already in the destination, to the destination. My first attempt was something like this: using System.IO; using System.Security.Cryptography; private static

问题 I\'m having a bit of a problem with the communication to an accelerometer sensor. The sensor puts out about 8000 readings/second continuously. The sensor is plugged in to a usb port with an adaper and shows up as com4. My problem is that I can\'t seem to pick out the sensor reading packets from the byte stream. The packets have the size of five bytes and have the following format: High nibble Low nibble Byte 1 checksum, id for packet start X high Byte 2 X mid X low Byte 3 Y high Y mid Byte 4

问题 How do I use the SHA1CryptoServiceProvider() on a file to create a SHA1 Checksum of the file? 回答1: using (FileStream fs = new FileStream(@"C:\file\location", FileMode.Open)) using (BufferedStream bs = new BufferedStream(fs)) { using (SHA1Managed sha1 = new SHA1Managed()) { byte[] hash = sha1.ComputeHash(bs); StringBuilder formatted = new StringBuilder(2 * hash.Length); foreach (byte b in hash) { formatted.AppendFormat("{0:X2}", b); } } } formatted contains the string representation of the SHA

问题 This question already has an answer here: Probability of SHA1 collisions 3 answers 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 the probability of getting duplicates is 0? OR is the calculation of SHA1 (hence probability of duplicates) independent of the length of the string? The goal I am trying to achieve is to hash some

问题 Typical approaches recommend reading the binary via FileStream and comparing it byte-by-byte. Would a checksum comparison such as CRC be faster? Are there any .NET libraries that can generate a checksum for a file? 回答1: A checksum comparison will most likely be slower than a byte-by-byte comparison. In order to generate a checksum, you'll need to load each byte of the file, and perform processing on it. You'll then have to do this on the second file. The processing will almost definitely be

问题 I am looking to use Java to get the MD5 checksum of a file. I was really surprised but I haven\'t been able to find anything that shows how to get the MD5 checksum of a file. How is it done? 回答1: There's an input stream decorator, java.security.DigestInputStream , so that you can compute the digest while using the input stream as you normally would, instead of having to make an extra pass over the data. MessageDigest md = MessageDigest.getInstance("MD5"); try (InputStream is = Files