C#关于MD5字符串计算哈希值

下面的代码示例计算字符串的 MD5 哈希值，并将该哈希作为 32 字符的十六进制格式字符串返回。此代码示例中创建的哈希字符串与能创建 32 字符的十六进制格式哈希字符串的任何 MD5 哈希函数（在任何平台上）兼容。

using System;
using System.Security.Cryptography;
using System.Text;

class Example
{
// Hash an input string and return the hash as
// a 32 character hexadecimal string.
static string getMd5Hash(string input)
{
// Create a new instance of the MD5CryptoServiceProvider object.
MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();

    // Convert the input string to a byte array and compute the hash.
    byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));

    // Create a new Stringbuilder to collect the bytes
    // and create a string.
    StringBuilder sBuilder = new StringBuilder();

    // Loop through each byte of the hashed data 
    // and format each one as a hexadecimal string.
    for (int i = 0; i < data.Length; i++)
    {
        sBuilder.Append(data[i].ToString("x2"));
    }

    // Return the hexadecimal string.
    return sBuilder.ToString();
}

// Verify a hash against a string.
static bool verifyMd5Hash(string input, string hash)
{
    // Hash the input.
    string hashOfInput = getMd5Hash(input);

    // Create a StringComparer an comare the hashes.
    StringComparer comparer = StringComparer.OrdinalIgnoreCase;

    if (0 == comparer.Compare(hashOfInput, hash))
    {
        return true;
    }
    else
    {
        return false;
    }
}


static void Main()
{
    string source = "Hello World!";
    
    string hash = getMd5Hash(source);

    Console.WriteLine("The MD5 hash of " + source + " is: " + hash + ".");

    Console.WriteLine("Verifying the hash...");

    if (verifyMd5Hash(source, hash))
    {
        Console.WriteLine("The hashes are the same.");
    }
    else
    {
        Console.WriteLine("The hashes are not same.");
    }
    
}

}
// This code example produces the following output:
//
// The MD5 hash of Hello World! is: ed076287532e86365e841e92bfc50d8c.
// Verifying the hash…
// The hashes are the same.