如何哈希密码

Posted 2021-04-05

嘿，我想在手机上存储密码的哈希，但我不知道该怎么做。我似乎只能找到加密方法。哈希密码的最佳方法是什么？谢谢

答案

更新：这个答案严重过时了。请使用https://stackoverflow.com/a/10402129/251311的建议。

你可以使用

var md5 = new MD5CryptoServiceProvider();
var md5data = md5.ComputeHash(data);

要么

var sha1 = new SHA1CryptoServiceProvider();
var sha1data = sha1.ComputeHash(data);

要将data作为字节数组，您可以使用

var data = Encoding.ASCII.GetBytes(password);

并从md5data或sha1data获取字符串

var hashedPassword = ASCIIEncoding.GetString(md5data);

另一答案

这里的大多数其他答案都与今天的最佳实践有些过时。因此，这里是使用PBKDF2 / Rfc2898DeriveBytes来存储和验证密码的应用。以下代码在这篇文章的独立类中：Another example of how to store a salted password hash。基础知识非常简单，所以在这里分解：

步骤1使用加密PRNG创建salt值：

byte[] salt;
new RNGCryptoServiceProvider().GetBytes(salt = new byte[16]);

步骤2创建Rfc2898DeriveBytes并获取哈希值：

var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 10000);
byte[] hash = pbkdf2.GetBytes(20);

步骤3将salt和password字节组合起来供以后使用：

byte[] hashBytes = new byte[36];
Array.Copy(salt, 0, hashBytes, 0, 16);
Array.Copy(hash, 0, hashBytes, 16, 20);

步骤4将组合的salt + hash转换为字符串进行存储

string savedPasswordHash = Convert.ToBase64String(hashBytes);
DBContext.AddUser(new User { ..., Password = savedPasswordHash });

步骤5根据存储的密码验证用户输入的密码

/* Fetch the stored value */
string savedPasswordHash = DBContext.GetUser(u => u.UserName == user).Password;
/* Extract the bytes */
byte[] hashBytes = Convert.FromBase64String(savedPasswordHash);
/* Get the salt */
byte[] salt = new byte[16];
Array.Copy(hashBytes, 0, salt, 0, 16);
/* Compute the hash on the password the user entered */
var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 10000);
byte[] hash = pbkdf2.GetBytes(20);
/* Compare the results */
for (int i=0; i < 20; i++)
    if (hashBytes[i+16] != hash[i])
        throw new UnauthorizedAccessException();

注意：根据特定应用程序的性能要求，可以减少值“10000”。最小值应该在1000左右。

另一答案

基于csharptest.net's很好的答案，我为此写了一个类：

public static class SecurePasswordHasher
{
    /// <summary>
    /// Size of salt.
    /// </summary>
    private const int SaltSize = 16;

    /// <summary>
    /// Size of hash.
    /// </summary>
    private const int HashSize = 20;

    /// <summary>
    /// Creates a hash from a password.
    /// </summary>
    /// <param name="password">The password.</param>
    /// <param name="iterations">Number of iterations.</param>
    /// <returns>The hash.</returns>
    public static string Hash(string password, int iterations)
    {
        // Create salt
        byte[] salt;
        new RNGCryptoServiceProvider().GetBytes(salt = new byte[SaltSize]);

        // Create hash
        var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);
        var hash = pbkdf2.GetBytes(HashSize);

        // Combine salt and hash
        var hashBytes = new byte[SaltSize + HashSize];
        Array.Copy(salt, 0, hashBytes, 0, SaltSize);
        Array.Copy(hash, 0, hashBytes, SaltSize, HashSize);

        // Convert to base64
        var base64Hash = Convert.ToBase64String(hashBytes);

        // Format hash with extra information
        return string.Format("$MYHASH$V1${0}${1}", iterations, base64Hash);
    }

    /// <summary>
    /// Creates a hash from a password with 10000 iterations
    /// </summary>
    /// <param name="password">The password.</param>
    /// <returns>The hash.</returns>
    public static string Hash(string password)
    {
        return Hash(password, 10000);
    }

    /// <summary>
    /// Checks if hash is supported.
    /// </summary>
    /// <param name="hashString">The hash.</param>
    /// <returns>Is supported?</returns>
    public static bool IsHashSupported(string hashString)
    {
        return hashString.Contains("$MYHASH$V1$");
    }

    /// <summary>
    /// Verifies a password against a hash.
    /// </summary>
    /// <param name="password">The password.</param>
    /// <param name="hashedPassword">The hash.</param>
    /// <returns>Could be verified?</returns>
    public static bool Verify(string password, string hashedPassword)
    {
        // Check hash
        if (!IsHashSupported(hashedPassword))
        {
            throw new NotSupportedException("The hashtype is not supported");
        }

        // Extract iteration and Base64 string
        var splittedHashString = hashedPassword.Replace("$MYHASH$V1$", "").Split('$');
        var iterations = int.Parse(splittedHashString[0]);
        var base64Hash = splittedHashString[1];

        // Get hash bytes
        var hashBytes = Convert.FromBase64String(base64Hash);

        // Get salt
        var salt = new byte[SaltSize];
        Array.Copy(hashBytes, 0, salt, 0, SaltSize);

        // Create hash with given salt
        var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);
        byte[] hash = pbkdf2.GetBytes(HashSize);

        // Get result
        for (var i = 0; i < HashSize; i++)
        {
            if (hashBytes[i + SaltSize] != hash[i])
            {
                return false;
            }
        }
        return true;
    }
}

用法：

// Hash
var hash = SecurePasswordHasher.Hash("mypassword");

// Verify
var result = SecurePasswordHasher.Verify("mypassword", hash);

示例哈希可以是这样的：

$MYHASH$V1$10000$Qhxzi6GNu/Lpy3iUqkeqR/J1hh8y/h5KPDjrv89KzfCVrubn

正如您所看到的，我还将哈希中的迭代包含在内以便于使用，如果我们需要升级，还可以升级它。

---

如果你对.net core感兴趣，我在Code Review上也有一个.net核心版本。

另一答案

我使用哈希和盐进行密码加密（它与Asp.Net Membership使用的哈希相同）：

private string PasswordSalt
{
   get
   {
      var rng = new RNGCryptoServiceProvider();
      var buff = new byte[32];
      rng.GetBytes(buff);
      return Convert.ToBase64String(buff);
   }
}

private string EncodePassword(string password, string salt)
{
   byte[] bytes = Encoding.Unicode.GetBytes(password);
   byte[] src = Encoding.Unicode.GetBytes(salt);
   byte[] dst = new byte[src.Length + bytes.Length];
   Buffer.BlockCopy(src, 0, dst, 0, src.Length);
   Buffer.BlockCopy(bytes, 0, dst, src.Length, bytes.Length);
   HashAlgorithm algorithm = HashAlgorithm.Create("SHA1");
   byte[] inarray = algorithm.ComputeHash(dst);
   return Convert.ToBase64String(inarray);
}