server/test/Api.Test/Utilities/KdfSettingsValidatorTests.cs

using Bit.Core.Enums;
using Bit.Core.KeyManagement.Models.Data;
using Bit.Core.Utilities;
using Xunit;

namespace Bit.Api.Test.Utilities;

public class KdfSettingsValidatorTests
{
    [Theory]
    [InlineData(KdfType.PBKDF2_SHA256, 1_000_000, null, null)] // Somewhere in the middle
    [InlineData(KdfType.PBKDF2_SHA256, 600_000, null, null)] // Right on the lower boundary
    [InlineData(KdfType.PBKDF2_SHA256, 2_000_000, null, null)] // Right on the upper boundary
    [InlineData(KdfType.Argon2id, 5, 500, 8)] // Somewhere in the middle
    [InlineData(KdfType.Argon2id, 2, 15, 1)] // Right on the lower boundary
    [InlineData(KdfType.Argon2id, 10, 1024, 16)] // Right on the upper boundary
    public void Validate_IsValid(KdfType kdfType, int kdfIterations, int? kdfMemory, int? kdfParallelism)
    {
        var results = KdfSettingsValidator.Validate(kdfType, kdfIterations, kdfMemory, kdfParallelism);
        Assert.Empty(results);
    }

    [Theory]
    [InlineData(KdfType.PBKDF2_SHA256, 500_000, null, null, 1)] // Too few iterations
    [InlineData(KdfType.PBKDF2_SHA256, 2_000_001, null, null, 1)] // Too many iterations
    [InlineData(KdfType.Argon2id, 0, 30, 8, 1)] // Iterations must be greater than 0
    [InlineData(KdfType.Argon2id, 10, 14, 8, 1)] // Too little memory
    [InlineData(KdfType.Argon2id, 10, 14, 0, 1)] // Too small of a parallelism value
    [InlineData(KdfType.Argon2id, 10, 1025, 8, 1)] // Too much memory
    [InlineData(KdfType.Argon2id, 10, 512, 17, 1)] // Too big of a parallelism value
    public void Validate_Fails(KdfType kdfType, int kdfIterations, int? kdfMemory, int? kdfParallelism, int expectedFailures)
    {
        var results = KdfSettingsValidator.Validate(kdfType, kdfIterations, kdfMemory, kdfParallelism);
        Assert.NotEmpty(results);
        Assert.Equal(expectedFailures, results.Count());
    }

    [Fact]
    public void ValidateAuthenticationAndUnlockData_WhenMatchingKdfAndSalt_ReturnsNoErrors()
    {
        var kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 };
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = kdf,
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Empty(results);
    }

    [Fact]
    public void ValidateAuthenticationAndUnlockData_WhenKdfMismatch_ReturnsKdfEqualityError()
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.Argon2id, Iterations = 3, Memory = 64, Parallelism = 4 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("AuthenticationData and UnlockData must have the same KDF configuration.", results[0].ErrorMessage);
    }

    [Fact]
    public void ValidateAuthenticationAndUnlockData_WhenSaltMismatch_ReturnsSaltEqualityError()
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt-auth"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt-unlock"
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Invalid master password salt.", results[0].ErrorMessage);
    }

    [Fact]
    public void ValidateAuthenticationAndUnlockData_WhenKdfInvalid_ReturnsKdfValidationError()
    {
        // Matching but out-of-range KDF (iterations below minimum for PBKDF2)
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 100 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 100 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Contains("KDF iterations must be between", results[0].ErrorMessage);
    }

    [Theory]
    [InlineData("")]
    [InlineData(" ")]
    [InlineData("\t")]
    [InlineData("\n")]
    public void ValidateAuthenticationAndUnlockData_WhenAuthSaltIsEmptyOrWhitespace_ReturnsSaltError(string salt)
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = salt
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Master password salt must not be empty.", results[0].ErrorMessage);
    }

    [Theory]
    [InlineData("")]
    [InlineData(" ")]
    [InlineData("\t")]
    [InlineData("\n")]
    public void ValidateAuthenticationAndUnlockData_WhenUnlockSaltIsEmptyOrWhitespace_ReturnsSaltError(string salt)
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = salt
        };

        var results = KdfSettingsValidator.ValidateAuthenticationAndUnlockData(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Master password salt must not be empty.", results[0].ErrorMessage);
    }

    [Fact]
    public void ValidateKdfAndSaltAgreement_WhenMatchingKdfAndSalt_ReturnsNoErrors()
    {
        var kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 };
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = kdf,
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        Assert.Empty(results);
    }

    [Fact]
    public void ValidateKdfAndSaltAgreement_WhenKdfMismatch_ReturnsKdfEqualityErrorAndShortCircuits()
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt-auth"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.Argon2id, Iterations = 3, Memory = 64, Parallelism = 4 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt-unlock"
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        // Asserts both that the KDF mismatch is reported AND that the salt-mismatch
        // check does not also fire — KDF mismatch should short-circuit the validator,
        // matching the behavior of ValidateAuthenticationAndUnlockData.
        Assert.Single(results);
        Assert.Equal("AuthenticationData and UnlockData must have the same KDF configuration.", results[0].ErrorMessage);
    }

    [Fact]
    public void ValidateKdfAndSaltAgreement_WhenSaltMismatch_ReturnsSaltEqualityError()
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt-auth"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt-unlock"
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Invalid master password salt.", results[0].ErrorMessage);
    }

    [Theory]
    [InlineData("")]
    [InlineData(" ")]
    [InlineData("\t")]
    [InlineData("\n")]
    public void ValidateKdfAndSaltAgreement_WhenAuthSaltIsEmptyOrWhitespace_ReturnsSaltError(string salt)
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = salt
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Master password salt must not be empty.", results[0].ErrorMessage);
    }

    [Theory]
    [InlineData("")]
    [InlineData(" ")]
    [InlineData("\t")]
    [InlineData("\n")]
    public void ValidateKdfAndSaltAgreement_WhenUnlockSaltIsEmptyOrWhitespace_ReturnsSaltError(string salt)
    {
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = new KdfSettings { KdfType = KdfType.PBKDF2_SHA256, Iterations = 600_000 },
            MasterKeyWrappedUserKey = "wrapped",
            Salt = salt
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        Assert.Single(results);
        Assert.Equal("Master password salt must not be empty.", results[0].ErrorMessage);
    }

    [Theory]
    [InlineData(KdfType.PBKDF2_SHA256, 1, null, null)] // far below minimum
    [InlineData(KdfType.PBKDF2_SHA256, 100_000, null, null)] // sub-minimum but plausible legacy
    [InlineData(KdfType.Argon2id, 1, 8, 1)] // sub-minimum Argon2id
    public void ValidateKdfAndSaltAgreement_WhenKdfBelowMinimum_DoesNotEmitRangeError(
        KdfType kdfType, int iterations, int? memory, int? parallelism)
    {
        // PM-27892 regression guard: this validator MUST NOT range-check the KDF — it
        // exists specifically so legacy-KDF users (whose stored KDF predates current
        // minimums) are not locked out of flows backed by UpdateExistingPasswordData
        // (change password, replace temp password, emergency-access takeover for
        // grantors with master password). Range enforcement at the boundary is the
        // job of ValidateAuthenticationAndUnlockData and is reserved for KDF-being-
        // chosen flows. If this test fails, the validator has been incorrectly
        // expanded to perform range validation and legacy-KDF users will be silently
        // rejected at the boundary.
        var kdf = new KdfSettings
        {
            KdfType = kdfType,
            Iterations = iterations,
            Memory = memory,
            Parallelism = parallelism
        };
        var authentication = new MasterPasswordAuthenticationData
        {
            Kdf = kdf,
            MasterPasswordAuthenticationHash = "hash",
            Salt = "salt"
        };
        var unlock = new MasterPasswordUnlockData
        {
            Kdf = kdf,
            MasterKeyWrappedUserKey = "wrapped",
            Salt = "salt"
        };

        var results = KdfSettingsValidator.ValidateKdfAndSaltAgreement(authentication, unlock).ToList();

        Assert.Empty(results);
    }
}