C#•2mo ago

Issue with unit test for Argon2-based password hash service

I'm encountering an issue with the implementation of a password hash service using the Argon2 algorithm. I've created a PasswordHasherService class that utilizes Argon2 to generate secure password hashes, along with a method to verify passwords. The implementation of the class seems to be correct, but I'm facing difficulties with a specific unit test. The unit test aims to verify if the VerifyPassword() method returns false when an incorrect salt is provided. Here's an overview of the problem: The PasswordHasherService class has three main methods: HashPassword(): generates a secure password hash using Argon2 and returns the hash along with the salt used. VerifyPassword(): checks if a provided password matches a provided password hash, taking into account the salt used during hash generation. GenerateSalt(): generates a random salt. The unit test in question, named VerifyPassword_ReturnsFalseForIncorrectSalt, checks if the VerifyPassword() method returns false when an incorrect salt is provided. However, even when intentionally providing an incorrect salt in the unit test, the returned result is true, indicating that the test is failing. I've reviewed the code multiple times and ensured that the implementation of the PasswordHasherService class is correct. I've also confirmed that the salt is being generated correctly using the GenerateSalt() method. However, I haven't been able to pinpoint the root cause of this issue. I'm reaching out to the community for assistance in understanding what might be causing this unexpected behavior and how I can fix my unit test to ensure it functions as expected. Any guidance or suggestions would be greatly appreciated. Thank you in advance for your help!

21 Replies

KaykiLetieri.cs•2mo ago

using Isopoh.Cryptography.Argon2;
using RegulatorioAuth.Application.Services.Interfaces;
using System.Security.Cryptography;
using System.Text;

namespace RegulatorioAuth.Application.Services;

public class PasswordHasherService : IPasswordHasherService
{
    public (string HashedPassword, byte[] Salt) HashPassword(string password)
    {
        var salt = GenerateSalt();

        Argon2Config argon2Config = new()
        {
            Type = Argon2Type.DataIndependentAddressing,
            Version = Argon2Version.Nineteen,
            MemoryCost = 65536,
            TimeCost = 4,
            Lanes = 8,
            Threads = 1,
            Password = Encoding.UTF8.GetBytes(password),
            Salt = salt
        };

        using Argon2 argon2 = new(argon2Config);
        using var hash = argon2.Hash();

        return (argon2Config.EncodeString(hash.Buffer), salt);
    }

    public bool VerifyPassword(string password, string hashedPassword, byte[] salt)
    {
        Argon2Config configOfPasswordToVerify = new Argon2Config
        {
            Type = Argon2Type.DataIndependentAddressing,
            Version = Argon2Version.Nineteen,
            MemoryCost = 65536,
            TimeCost = 4,
            Lanes = 8,
            Threads = 1,
            Password = Encoding.UTF8.GetBytes(password),
            Salt = salt
        };

        return Argon2.Verify(hashedPassword, configOfPasswordToVerify);
    }

    public byte[] GenerateSalt()
    {
        byte[] salt = new byte[16];
        using (var rng = RandomNumberGenerator.Create())
        {
            rng.GetBytes(salt);
        }
        return salt;
    }
}

using Isopoh.Cryptography.Argon2;
using RegulatorioAuth.Application.Services.Interfaces;
using System.Security.Cryptography;
using System.Text;

namespace RegulatorioAuth.Application.Services;

public class PasswordHasherService : IPasswordHasherService
{
    public (string HashedPassword, byte[] Salt) HashPassword(string password)
    {
        var salt = GenerateSalt();

        Argon2Config argon2Config = new()
        {
            Type = Argon2Type.DataIndependentAddressing,
            Version = Argon2Version.Nineteen,
            MemoryCost = 65536,
            TimeCost = 4,
            Lanes = 8,
            Threads = 1,
            Password = Encoding.UTF8.GetBytes(password),
            Salt = salt
        };

        using Argon2 argon2 = new(argon2Config);
        using var hash = argon2.Hash();

        return (argon2Config.EncodeString(hash.Buffer), salt);
    }

    public bool VerifyPassword(string password, string hashedPassword, byte[] salt)
    {
        Argon2Config configOfPasswordToVerify = new Argon2Config
        {
            Type = Argon2Type.DataIndependentAddressing,
            Version = Argon2Version.Nineteen,
            MemoryCost = 65536,
            TimeCost = 4,
            Lanes = 8,
            Threads = 1,
            Password = Encoding.UTF8.GetBytes(password),
            Salt = salt
        };

        return Argon2.Verify(hashedPassword, configOfPasswordToVerify);
    }

    public byte[] GenerateSalt()
    {
        byte[] salt = new byte[16];
        using (var rng = RandomNumberGenerator.Create())
        {
            rng.GetBytes(salt);
        }
        return salt;
    }
}

[Fact]
public void VerifyPassword_ReturnsFalseForIncorrectSalt()
{
    // Arrange
    string password = "password123";
    var (hashedPassword, _) = _passwordHasherService.HashPassword(password);
    byte[] incorrectSalt = Encoding.UTF8.GetBytes("WrongSalt");

    // Act
    bool result = _passwordHasherService.VerifyPassword(password, hashedPassword, incorrectSalt);

    // Assert
    Assert.False(result);
}

[Fact]
public void VerifyPassword_ReturnsFalseForIncorrectSalt()
{
    // Arrange
    string password = "password123";
    var (hashedPassword, _) = _passwordHasherService.HashPassword(password);
    byte[] incorrectSalt = Encoding.UTF8.GetBytes("WrongSalt");

    // Act
    bool result = _passwordHasherService.VerifyPassword(password, hashedPassword, incorrectSalt);

    // Assert
    Assert.False(result);
}

Assert.False() Failure
Expected: False
Actual:   True

Assert.False() Failure
Expected: False
Actual:   True

qqdev•2mo ago

So VerifyPassword returns true for the wrong salt

KaykiLetieri.cs•2mo ago

yep

qqdev•2mo ago

That's interesting

KaykiLetieri.cs•2mo ago

It could be an error with the Isopoh.Cryptography.Argon2 library?

qqdev•2mo ago

Maybe. The usage looks fine to me

qqdev•2mo ago

qqdev•2mo ago

Might wanna try this one if you can: https://github.com/kmaragon/Konscious.Security.Cryptography E: Has its own issues

qqdev•2mo ago

https://github.com/mheyman/Isopoh.Cryptography.Argon2/issues/52

GitHub

Hash without salt is corrupt · Issue #52 · mheyman/Isopoh.Cryptogra...

Seems kind of basic, but the hash is corrupt if a salt isn't supplied. Argon2.Hash(new Argon2Config { Password = Encoding.UTF8.GetBytes("test") }) // $argon2id$v=19$m=65536,t=3,p=4 Ar...

qqdev•2mo ago

Stuff like that makes me worry ;D

KaykiLetieri.cs•2mo ago

really I'm going to switch thank you very much

qqdev•2mo ago

Do you have to use argon2?

qqdev•2mo ago

If not: https://stackoverflow.com/a/73126492

Stack Overflow

Hash and salt passwords in C#

I was just going through one of DavidHayden's articles on Hashing User Passwords. Really I can't get what he is trying to achieve. Here is his code: private static string CreateSalt(int size) { ...

KaykiLetieri.cs•2mo ago

Is it better than using Argon2?

qqdev•2mo ago

Google "argon2 vs PBKDF2" for more info on that

qqdev•2mo ago

https://github.com/OWASP/CheatSheetSeries/blob/master/cheatsheets/Password_Storage_Cheat_Sheet.md

GitHub

CheatSheetSeries/cheatsheets/Password_Storage_Cheat_Sheet.md at mas...

The OWASP Cheat Sheet Series was created to provide a concise collection of high value information on specific application security topics. - OWASP/CheatSheetSeries

KaykiLetieri.cs•2mo ago

Thank you very much I'll check it out

Lisa•2mo ago

This is because you are using argon2Config.EncodeString EncodeString includes information about how the hash was computed, including the salt. In this case the provided salt is ignored and the salt from the hashstring is used.

Lisa•2mo ago

// See https://aka.ms/new-console-template for more information

using System.Security.Cryptography;
using Isopoh.Cryptography.Argon2;

var salt = new byte[16];
using (var rng = RandomNumberGenerator.Create())
{
    rng.GetBytes(salt);
}

Console.WriteLine(salt.ToB64String());

Argon2Config argon2Config = new()
{
    Type = Argon2Type.DataIndependentAddressing,
    Version = Argon2Version.Nineteen,
    MemoryCost = 65536,
    TimeCost = 4,
    Lanes = 8,
    Threads = 1,
    Password = "somepassword"u8.ToArray(),
    Salt = salt
};

var argon2 = new Argon2(argon2Config);

var hash = argon2Config.EncodeString(argon2.Hash().Buffer);
Console.WriteLine(hash);

// See https://aka.ms/new-console-template for more information

using System.Security.Cryptography;
using Isopoh.Cryptography.Argon2;

var salt = new byte[16];
using (var rng = RandomNumberGenerator.Create())
{
    rng.GetBytes(salt);
}

Console.WriteLine(salt.ToB64String());

Argon2Config argon2Config = new()
{
    Type = Argon2Type.DataIndependentAddressing,
    Version = Argon2Version.Nineteen,
    MemoryCost = 65536,
    TimeCost = 4,
    Lanes = 8,
    Threads = 1,
    Password = "somepassword"u8.ToArray(),
    Salt = salt
};

var argon2 = new Argon2(argon2Config);

var hash = argon2Config.EncodeString(argon2.Hash().Buffer);
Console.WriteLine(hash);

Lisa•2mo ago

As you can see the salt is included in plaintext in the encoded string.

KaykiLetieri.cs•2mo ago

Thanks

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Issue with unit test for Argon2-based password hash service