如何在C#/ Bouncy Castle中创建PBKDF2-SHA256密码哈希

Question

我需要创建一个PBKDF2-SHA256密码哈希,但是遇到了一些麻烦.

我下载了Bouncy Castle的回购,但在单元测试中找到了我想要的东西.

在这里找到了一些示例代码,但这只是SHA1.代码的关键点是:

/// <summary>
/// Computes the PBKDF2-SHA1 hash of a password.
/// </summary>
/// <param name="password">The password to hash.</param>
/// <param name="salt">The salt.</param>
/// <param name="iterations">The PBKDF2 iteration count.</param>
/// <param name="outputBytes">The length of the hash to generate, in bytes.</param>
/// <returns>A hash of the password.</returns>
private static byte[] PBKDF2(string password, byte[] salt, int iterations, int outputBytes)
{
    var pdb = new Pkcs5S2ParametersGenerator();
    pdb.Init(PbeParametersGenerator.Pkcs5PasswordToBytes(password.ToCharArray()), salt,
                 iterations);
    var key = (KeyParameter)pdb.GenerateDerivedMacParameters(outputBytes * 8);
    return key.GetKey();
}

我需要将它从SHA1更改为SHA256.

从Java文档和这篇文章看,它看起来可能如下,但C#库中的构造函数没有重载.

var pdb = new Pkcs5S2ParametersGenerator(new Sha256Derived());

找到关于堆栈溢出的另一篇文章,我认为以下可能是可能的,但SHA散列算法不在查找列表中,因此以下内容不起作用.

var bcparam = (KeyParameter)pdb.GenerateDerivedParameters("sha256", outputBytes * 8);

我需要做些什么才能让它正常工作？

注意:如果你读过这篇文章并且不知道如何在Bouncy Castle,但确实知道另一种方式,我仍然感谢你的帮助.

Answer 1

编辑(为简洁起见删除了以前的答案历史记录)

现在有一个可以使用的Bouncy Castle Crypto API NuGet包.或者,您可以直接从GitHub 获取源代码,这将起作用.我从NuGet获得了标准的Bouncy Castle,在撰写本文时尚未更新为1.8.1.

为了搜索者的利益,这里有一个用于散列的C#助手类.已经在多线程上测试过,看起来很好.

注意:此类也适用于库BouncyCastle.NetCore的.NET Core版本

/// <summary>
/// Contains the relevant Bouncy Castle Methods required to encrypt a password.
/// References NuGet Package BouncyCastle.Crypto.dll
/// </summary>
public class BouncyCastleHashing
{
    private SecureRandom _cryptoRandom;

    public BouncyCastleHashing()
    {
        _cryptoRandom = new SecureRandom();
    }

    /// <summary>
    /// Random Salt Creation
    /// </summary>
    /// <param name="size">The size of the salt in bytes</param>
    /// <returns>A random salt of the required size.</returns>
    public byte[] CreateSalt(int size)
    {
        byte[] salt = new byte[size];
        _cryptoRandom.NextBytes(salt);
        return salt;
    }

    /// <summary>
    /// Gets a PBKDF2_SHA256 Hash  (Overload)
    /// </summary>
    /// <param name="password">The password as a plain text string</param>
    /// <param name="saltAsBase64String">The salt for the password</param>
    /// <param name="iterations">The number of times to encrypt the password</param>
    /// <param name="hashByteSize">The byte size of the final hash</param>
    /// <returns>A base64 string of the hash.</returns>
    public string PBKDF2_SHA256_GetHash(string password, string saltAsBase64String, int iterations, int hashByteSize)
    {
        var saltBytes = Convert.FromBase64String(saltAsBase64String);

        var hash = PBKDF2_SHA256_GetHash(password, saltBytes, iterations, hashByteSize);

        return Convert.ToBase64String(hash);
    }

    /// <summary>
    /// Gets a PBKDF2_SHA256 Hash (CORE METHOD)
    /// </summary>
    /// <param name="password">The password as a plain text string</param>
    /// <param name="salt">The salt as a byte array</param>
    /// <param name="iterations">The number of times to encrypt the password</param>
    /// <param name="hashByteSize">The byte size of the final hash</param>
    /// <returns>A the hash as a byte array.</returns>
    public byte[] PBKDF2_SHA256_GetHash(string password, byte[] salt, int iterations, int hashByteSize)
    {
        var pdb = new Pkcs5S2ParametersGenerator(new Org.BouncyCastle.Crypto.Digests.Sha256Digest());
        pdb.Init(PbeParametersGenerator.Pkcs5PasswordToBytes(password.ToCharArray()), salt,
                     iterations);
        var key = (KeyParameter)pdb.GenerateDerivedMacParameters(hashByteSize * 8);
        return key.GetKey();
    }

    /// <summary>
    /// Validates a password given a hash of the correct one. (OVERLOAD)
    /// </summary>
    /// <param name="password">The original password to hash</param>
    /// <param name="salt">The salt that was used when hashing the password</param>
    /// <param name="iterations">The number of times it was encrypted</param>
    /// <param name="hashByteSize">The byte size of the final hash</param>
    /// <param name="hashAsBase64String">The hash the password previously provided as a base64 string</param>
    /// <returns>True if the hashes match</returns>
    public bool ValidatePassword(string password, string salt, int iterations, int hashByteSize, string hashAsBase64String)
    {
        byte[] saltBytes = Convert.FromBase64String(salt);
        byte[] actualHashBytes = Convert.FromBase64String(hashAsBase64String);
        return ValidatePassword(password, saltBytes, iterations, hashByteSize, actualHashBytes);
    }

    /// <summary>
    /// Validates a password given a hash of the correct one (MAIN METHOD).
    /// </summary>
    /// <param name="password">The password to check.</param>
    /// <param name="correctHash">A hash of the correct password.</param>
    /// <returns>True if the password is correct. False otherwise.</returns>
    public bool ValidatePassword(string password, byte[] saltBytes, int iterations, int hashByteSize, byte[] actualGainedHasAsByteArray)
    {
        byte[] testHash = PBKDF2_SHA256_GetHash(password, saltBytes, iterations, hashByteSize);
        return SlowEquals(actualGainedHasAsByteArray, testHash);
    }

    /// <summary>
    /// Compares two byte arrays in length-constant time. This comparison
    /// method is used so that password hashes cannot be extracted from
    /// on-line systems using a timing attack and then attacked off-line.
    /// </summary>
    /// <param name="a">The first byte array.</param>
    /// <param name="b">The second byte array.</param>
    /// <returns>True if both byte arrays are equal. False otherwise.</returns>
    private bool SlowEquals(byte[] a, byte[] b)
    {
        uint diff = (uint)a.Length ^ (uint)b.Length;
        for (int i = 0; i < a.Length && i < b.Length; i++)
            diff |= (uint)(a[i] ^ b[i]);
        return diff == 0;
    }

}

用法示例

public void CreatePasswordHash_Single()
{
    int iterations = 100000; // The number of times to encrypt the password - change this
    int saltByteSize = 64; // the salt size - change this
    int hashByteSize = 128; // the final hash - change this

    BouncyCastleHashing mainHashingLib = new BouncyCastleHashing();

    var password = "password"; // That's really secure! :)

    byte[] saltBytes = mainHashingLib.CreateSalt(saltByteSize);
    string saltString = Convert.ToBase64String(saltBytes);

    string pwdHash = mainHashingLib.PBKDF2_SHA256_GetHash(password, saltString, iterations, hashByteSize);

    var isValid = mainHashingLib.ValidatePassword(password, saltBytes, iterations, hashByteSize, Convert.FromBase64String(pwdHash));

}