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HMAC-SHA256 C# 範例 資料來源: https://docs.microsoft.com/zh-tw/dotnet/api/system.security.cryptography.hmacsha256?view=net-5.0 https://marcus116.blogspot.com/2019/06/how-to-create-hmacsha256-cryptographyin-csharp.html 01.下列範例示範如何使用物件來簽署檔案 HMACSHA256 ，以及如何驗證檔案 using System; using System.IO; using System.Security.Cryptography; public class HMACSHA256example { public static void Main(string[] Fileargs) { string dataFile; string signedFile; //If no file names are specified, create them. if (Fileargs.Length < 2) { dataFile = @"text.txt"; signedFile = "signedFile.enc"; if (!File.Exists(dataFile)) { // Create a file to write to. using (StreamWriter sw = File.CreateText(dataFile)) { sw.WriteLine("Here is a message to sign"); } } } else { dataFile = Fileargs[0]; signedFile = Fileargs[1]; } try { // Create a random key using a random number generator. This would be the // secret key shared by sender and receiver. byte[] secretkey = new Byte[64]; //RNGCryptoServiceProvider is an implementation of a random number generator. using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider()) { // The array is now filled with cryptographically strong random bytes. rng.GetBytes(secretkey); // Use the secret key to sign the message file. SignFile(secretkey, dataFile, signedFile); // Verify the signed file VerifyFile(secretkey, signedFile); } } catch (IOException e) { Console.WriteLine("Error: File not found", e); } } //end main // Computes a keyed hash for a source file and creates a target file with the keyed hash // prepended to the contents of the source file. public static void SignFile(byte[] key, String sourceFile, String destFile) { // Initialize the keyed hash object. using (HMACSHA256 hmac = new HMACSHA256(key)) { using (FileStream inStream = new FileStream(sourceFile, FileMode.Open)) { using (FileStream outStream = new FileStream(destFile, FileMode.Create)) { // Compute the hash of the input file. byte[] hashValue = hmac.ComputeHash(inStream); // Reset inStream to the beginning of the file. inStream.Position = 0; // Write the computed hash value to the output file. outStream.Write(hashValue, 0, hashValue.Length); // Copy the contents of the sourceFile to the destFile. int bytesRead; // read 1K at a time byte[] buffer = new byte[1024]; do { // Read from the wrapping CryptoStream. bytesRead = inStream.Read(buffer, 0, 1024); outStream.Write(buffer, 0, bytesRead); } while (bytesRead > 0); } } } return; } // end SignFile // Compares the key in the source file with a new key created for the data portion of the file. If the keys // compare the data has not been tampered with. public static bool VerifyFile(byte[] key, String sourceFile) { bool err = false; // Initialize the keyed hash object. using (HMACSHA256 hmac = new HMACSHA256(key)) { // Create an array to hold the keyed hash value read from the file. byte[] storedHash = new byte[hmac.HashSize / 8]; // Create a FileStream for the source file. using (FileStream inStream = new FileStream(sourceFile, FileMode.Open)) { // Read in the storedHash. inStream.Read(storedHash, 0, storedHash.Length); // Compute the hash of the remaining contents of the file. // The stream is properly positioned at the beginning of the content, // immediately after the stored hash value. byte[] computedHash = hmac.ComputeHash(inStream); // compare the computed hash with the stored value for (int i = 0; i < storedHash.Length; i++) { if (computedHash[i] != storedHash[i]) { err = true; } } } } if (err) { Console.WriteLine("Hash values differ! Signed file has been tampered with!"); return false; } else { Console.WriteLine("Hash values agree -- no tampering occurred."); return true; } } //end VerifyFile } //end class 02.單純字串加密 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.IO; using System.Security.Cryptography; namespace CS_Console_HMACSHA256 { class Program { private static string HMACSHA256(string message, string key) { var encoding = new System.Text.UTF8Encoding(); byte[] keyByte = encoding.GetBytes(key); byte[] messageBytes = encoding.GetBytes(message); using (var hmacSHA256 = new HMACSHA256(keyByte)) { byte[] hashMessage = hmacSHA256.ComputeHash(messageBytes); return BitConverter.ToString(hashMessage).Replace("-", "").ToLower(); } } static void Pause() { Console.Write("Press any key to continue..."); Console.ReadKey(true); } static void Main(string[] args) { String StrHMACSHA256 = ""; StrHMACSHA256 = HMACSHA256("TEST", "KEY"); Console.WriteLine(StrHMACSHA256);// resulg : 615dac1c53c9396d8f69a419a0b2d9393a0461d7ad5f7f3d9beb57264129ef12 Pause(); } } }