[PM-22696] send enumeration protection (#6352)

* feat: add static enumeration helper class
* test: add enumeration helper class unit tests

* feat: implement NeverAuthenticateValidator
* test: unit and integration tests SendNeverAuthenticateValidator

* test: use static class for common integration test setup for Send Access unit and integration tests
* test: update tests to use static helper

src/Core/Settings/GlobalSettings.cs

@@ -92,6 +92,10 @@ public class GlobalSettings : IGlobalSettings
     public virtual int SendAccessTokenLifetimeInMinutes { get; set; } = 5;
     public virtual bool EnableEmailVerification { get; set; }
     public virtual string KdfDefaultHashKey { get; set; }
+    /// <summary>
+    /// This Hash Key is used to prevent enumeration attacks against the Send Access feature.
+    /// </summary>
+    public virtual string SendDefaultHashKey { get; set; }
     public virtual string PricingUri { get; set; }
 
     public string BuildExternalUri(string explicitValue, string name)

src/Core/Utilities/EnumerationProtectionHelpers.cs

@@ -0,0 +1,36 @@
+using System.Text;
+
+namespace Bit.Core.Utilities;
+
+public static class EnumerationProtectionHelpers
+{
+    /// <summary>
+    /// Use this method to get a consistent int result based on the inputString that is in the range.
+    /// The same inputString will always return the same index result based on range input.
+    /// </summary>
+    /// <param name="hmacKey">Key used to derive the HMAC hash. Use a different key for each usage for optimal security</param>
+    /// <param name="inputString">The string to derive an index result</param>
+    /// <param name="range">The range of possible index values</param>
+    /// <returns>An int between 0 and range - 1</returns>
+    public static int GetIndexForInputHash(byte[] hmacKey, string inputString, int range)
+    {
+        if (hmacKey == null || range <= 0 || hmacKey.Length == 0)
+        {
+            return 0;
+        }
+        else
+        {
+            // Compute the HMAC hash of the salt
+            var hmacMessage = Encoding.UTF8.GetBytes(inputString.Trim().ToLowerInvariant());
+            using var hmac = new System.Security.Cryptography.HMACSHA256(hmacKey);
+            var hmacHash = hmac.ComputeHash(hmacMessage);
+            // Convert the hash to a number
+            var hashHex = BitConverter.ToString(hmacHash).Replace("-", string.Empty).ToLowerInvariant();
+            var hashFirst8Bytes = hashHex[..16];
+            var hashNumber = long.Parse(hashFirst8Bytes, System.Globalization.NumberStyles.HexNumber);
+            // Find the default KDF value for this hash number
+            var hashIndex = (int)(Math.Abs(hashNumber) % range);
+            return hashIndex;
+        }
+    }
+}

src/Identity/IdentityServer/RequestValidators/SendAccess/SendAccessConstants.cs

@@ -34,18 +34,18 @@ public static class SendAccessConstants
         public const string Otp = "otp";
     }
 
-    public static class GrantValidatorResults
+    public static class SendIdGuidValidatorResults
     {
         /// <summary>
-        /// The sendId is valid and the request is well formed. Not returned in any response.
+        /// The <see cref="TokenRequest.SendId"/> in the request is a valid GUID and the request is well formed. Not returned in any response.
         /// </summary>
         public const string ValidSendGuid = "valid_send_guid";
         /// <summary>
-        /// The sendId is missing from the request.
+        /// The <see cref="TokenRequest.SendId"/> is missing from the request.
         /// </summary>
         public const string SendIdRequired = "send_id_required";
         /// <summary>
-        /// The sendId is invalid, does not match a known send.
+        /// The <see cref="TokenRequest.SendId"/> is invalid, does not match a known send.
         /// </summary>
         public const string InvalidSendId = "send_id_invalid";
     }
@@ -53,11 +53,11 @@ public static class SendAccessConstants
     public static class PasswordValidatorResults
     {
         /// <summary>
-        /// The passwordHashB64 does not match the send's password hash.
+        /// The <see cref="TokenRequest.ClientB64HashedPassword"/> does not match the send's password hash.
         /// </summary>
         public const string RequestPasswordDoesNotMatch = "password_hash_b64_invalid";
         /// <summary>
-        /// The passwordHashB64 is missing from the request.
+        /// The <see cref="TokenRequest.ClientB64HashedPassword"/> is missing from the request.
         /// </summary>
         public const string RequestPasswordIsRequired = "password_hash_b64_required";
     }
@@ -105,4 +105,14 @@ public static class SendAccessConstants
     {
         public const string Subject = "Your Bitwarden Send verification code is {0}";
     }
+
+    /// <summary>
+    /// We use these static strings to help guide the enumeration protection logic.
+    /// </summary>
+    public static class EnumerationProtection
+    {
+        public const string Guid = "guid";
+        public const string Password = "password";
+        public const string Email = "email";
+    }
 }

src/Identity/IdentityServer/RequestValidators/SendAccess/SendAccessGrantValidator.cs

@@ -13,21 +13,19 @@ namespace Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 
 public class SendAccessGrantValidator(
     ISendAuthenticationQuery _sendAuthenticationQuery,
+    ISendAuthenticationMethodValidator<NeverAuthenticate> _sendNeverAuthenticateValidator,
     ISendAuthenticationMethodValidator<ResourcePassword> _sendPasswordRequestValidator,
     ISendAuthenticationMethodValidator<EmailOtp> _sendEmailOtpRequestValidator,
-    IFeatureService _featureService)
-: IExtensionGrantValidator
+    IFeatureService _featureService) : IExtensionGrantValidator
 {
     string IExtensionGrantValidator.GrantType => CustomGrantTypes.SendAccess;
 
-    private static readonly Dictionary<string, string>
-    _sendGrantValidatorErrorDescriptions = new()
+    private static readonly Dictionary<string, string> _sendGrantValidatorErrorDescriptions = new()
     {
-        { SendAccessConstants.GrantValidatorResults.SendIdRequired, $"{SendAccessConstants.TokenRequest.SendId} is required." },
-        { SendAccessConstants.GrantValidatorResults.InvalidSendId, $"{SendAccessConstants.TokenRequest.SendId} is invalid." }
+        { SendAccessConstants.SendIdGuidValidatorResults.SendIdRequired, $"{SendAccessConstants.TokenRequest.SendId} is required." },
+        { SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId, $"{SendAccessConstants.TokenRequest.SendId} is invalid." }
     };
 
-
     public async Task ValidateAsync(ExtensionGrantValidationContext context)
     {
         // Check the feature flag
@@ -38,7 +36,7 @@ public class SendAccessGrantValidator(
         }
 
         var (sendIdGuid, result) = GetRequestSendId(context);
-        if (result != SendAccessConstants.GrantValidatorResults.ValidSendGuid)
+        if (result != SendAccessConstants.SendIdGuidValidatorResults.ValidSendGuid)
         {
             context.Result = BuildErrorResult(result);
             return;
@@ -49,15 +47,10 @@ public class SendAccessGrantValidator(
 
         switch (method)
         {
-            case NeverAuthenticate:
+            case NeverAuthenticate never:
                 // null send scenario.
-                // TODO PM-22675: Add send enumeration protection here (primarily benefits self hosted instances).
-                // We should only map to password or email + OTP protected.
-                // If user submits password guess for a falsely protected send, then we will return invalid password.
-                // If user submits email + OTP guess for a falsely protected send, then we will return email sent, do not actually send an email.
-                context.Result = BuildErrorResult(SendAccessConstants.GrantValidatorResults.InvalidSendId);
+                context.Result = await _sendNeverAuthenticateValidator.ValidateRequestAsync(context, never, sendIdGuid);
                 return;
-
             case NotAuthenticated:
                 // automatically issue access token
                 context.Result = BuildBaseSuccessResult(sendIdGuid);
@@ -90,7 +83,7 @@ public class SendAccessGrantValidator(
         // if the sendId is null then the request is the wrong shape and the request is invalid
         if (sendId == null)
         {
-            return (Guid.Empty, SendAccessConstants.GrantValidatorResults.SendIdRequired);
+            return (Guid.Empty, SendAccessConstants.SendIdGuidValidatorResults.SendIdRequired);
         }
         // the send_id is not null so the request is the correct shape, so we will attempt to parse it
         try
@@ -100,20 +93,20 @@ public class SendAccessGrantValidator(
             // Guid.Empty indicates an invalid send_id return invalid grant
             if (sendGuid == Guid.Empty)
             {
-                return (Guid.Empty, SendAccessConstants.GrantValidatorResults.InvalidSendId);
+                return (Guid.Empty, SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId);
             }
-            return (sendGuid, SendAccessConstants.GrantValidatorResults.ValidSendGuid);
+            return (sendGuid, SendAccessConstants.SendIdGuidValidatorResults.ValidSendGuid);
         }
         catch
         {
-            return (Guid.Empty, SendAccessConstants.GrantValidatorResults.InvalidSendId);
+            return (Guid.Empty, SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId);
         }
     }
 
     /// <summary>
     /// Builds an error result for the specified error type.
     /// </summary>
-    /// <param name="error">This error is a constant string from <see cref="SendAccessConstants.GrantValidatorResults"/></param>
+    /// <param name="error">This error is a constant string from <see cref="SendAccessConstants.SendIdGuidValidatorResults"/></param>
     /// <returns>The error result.</returns>
     private static GrantValidationResult BuildErrorResult(string error)
     {
@@ -125,12 +118,12 @@ public class SendAccessGrantValidator(
         return error switch
         {
             // Request is the wrong shape
-            SendAccessConstants.GrantValidatorResults.SendIdRequired => new GrantValidationResult(
+            SendAccessConstants.SendIdGuidValidatorResults.SendIdRequired => new GrantValidationResult(
                                 TokenRequestErrors.InvalidRequest,
                                 errorDescription: _sendGrantValidatorErrorDescriptions[error],
                                 customResponse),
             // Request is correct shape but data is bad
-            SendAccessConstants.GrantValidatorResults.InvalidSendId => new GrantValidationResult(
+            SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId => new GrantValidationResult(
                                 TokenRequestErrors.InvalidGrant,
                                 errorDescription: _sendGrantValidatorErrorDescriptions[error],
                                 customResponse),

src/Identity/IdentityServer/RequestValidators/SendAccess/SendNeverAuthenticateRequestValidator.cs

@@ -0,0 +1,87 @@
+using System.Text;
+using Bit.Core.Settings;
+using Bit.Core.Tools.Models.Data;
+using Bit.Core.Utilities;
+using Duende.IdentityServer.Models;
+using Duende.IdentityServer.Validation;
+
+namespace Bit.Identity.IdentityServer.RequestValidators.SendAccess;
+
+/// <summary>
+/// This class is used to protect our system from enumeration attacks. This Validator will always return an error result.
+/// We hash the SendId Guid passed into the request to select the an error from the list of possible errors. This ensures
+/// that the same error is always returned for the same SendId.
+/// </summary>
+/// <param name="globalSettings">We need access to a hash key to generate the error index.</param>
+public class SendNeverAuthenticateRequestValidator(GlobalSettings globalSettings) : ISendAuthenticationMethodValidator<NeverAuthenticate>
+{
+    private readonly string[] _errorOptions =
+    [
+        SendAccessConstants.EnumerationProtection.Guid,
+        SendAccessConstants.EnumerationProtection.Password,
+        SendAccessConstants.EnumerationProtection.Email
+    ];
+
+    public Task<GrantValidationResult> ValidateRequestAsync(
+        ExtensionGrantValidationContext context,
+        NeverAuthenticate authMethod,
+        Guid sendId)
+    {
+        var neverAuthenticateError = GetErrorIndex(sendId, _errorOptions.Length);
+        var request = context.Request.Raw;
+        var errorType = neverAuthenticateError;
+
+        switch (neverAuthenticateError)
+        {
+            case SendAccessConstants.EnumerationProtection.Guid:
+                errorType = SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId;
+                break;
+            case SendAccessConstants.EnumerationProtection.Email:
+                var hasEmail = request.Get(SendAccessConstants.TokenRequest.Email) is not null;
+                errorType = hasEmail ? SendAccessConstants.EmailOtpValidatorResults.EmailInvalid
+                    : SendAccessConstants.EmailOtpValidatorResults.EmailRequired;
+                break;
+            case SendAccessConstants.EnumerationProtection.Password:
+                var hasPassword = request.Get(SendAccessConstants.TokenRequest.ClientB64HashedPassword) is not null;
+                errorType = hasPassword ? SendAccessConstants.PasswordValidatorResults.RequestPasswordDoesNotMatch
+                    : SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired;
+                break;
+        }
+
+        return Task.FromResult(BuildErrorResult(errorType));
+    }
+
+    private static GrantValidationResult BuildErrorResult(string errorType)
+    {
+        // Create error response with custom response data
+        var customResponse = new Dictionary<string, object>
+        {
+            { SendAccessConstants.SendAccessError, errorType }
+        };
+
+        var requestError = errorType switch
+        {
+            SendAccessConstants.EnumerationProtection.Guid => TokenRequestErrors.InvalidGrant,
+            SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired => TokenRequestErrors.InvalidGrant,
+            SendAccessConstants.PasswordValidatorResults.RequestPasswordDoesNotMatch => TokenRequestErrors.InvalidRequest,
+            SendAccessConstants.EmailOtpValidatorResults.EmailInvalid => TokenRequestErrors.InvalidGrant,
+            SendAccessConstants.EmailOtpValidatorResults.EmailRequired => TokenRequestErrors.InvalidRequest,
+            _ => TokenRequestErrors.InvalidGrant
+        };
+
+        return new GrantValidationResult(requestError, errorType, customResponse);
+    }
+
+    private string GetErrorIndex(Guid sendId, int range)
+    {
+        var salt = sendId.ToString();
+        byte[] hmacKey = [];
+        if (CoreHelpers.SettingHasValue(globalSettings.SendDefaultHashKey))
+        {
+            hmacKey = Encoding.UTF8.GetBytes(globalSettings.SendDefaultHashKey);
+        }
+
+        var index = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+        return _errorOptions[index];
+    }
+}

src/Identity/Utilities/ServiceCollectionExtensions.cs

@@ -29,6 +29,7 @@ public static class ServiceCollectionExtensions
         services.AddTransient<ILoginApprovingClientTypes, LoginApprovingClientTypes>();
         services.AddTransient<ISendAuthenticationMethodValidator<ResourcePassword>, SendPasswordRequestValidator>();
         services.AddTransient<ISendAuthenticationMethodValidator<EmailOtp>, SendEmailOtpRequestValidator>();
+        services.AddTransient<ISendAuthenticationMethodValidator<NeverAuthenticate>, SendNeverAuthenticateRequestValidator>();
 
         var issuerUri = new Uri(globalSettings.BaseServiceUri.InternalIdentity);
         var identityServerBuilder = services

test/Core.Test/Utilities/EnumerationProtectionHelpersTests.cs

@@ -0,0 +1,230 @@
+using System.Security.Cryptography;
+using System.Text;
+using Bit.Core.Utilities;
+using Xunit;
+
+namespace Bit.Core.Test.Utilities;
+
+public class EnumerationProtectionHelpersTests
+{
+    #region GetIndexForInputHash Tests
+
+    [Fact]
+    public void GetIndexForInputHash_NullHmacKey_ReturnsZero()
+    {
+        // Arrange
+        byte[] hmacKey = null;
+        var salt = "test@example.com";
+        var range = 10;
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(0, result);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_ZeroRange_ReturnsZero()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "test@example.com";
+        var range = 0;
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(0, result);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_NegativeRange_ReturnsZero()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "test@example.com";
+        var range = -5;
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(0, result);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_ValidInputs_ReturnsConsistentResult()
+    {
+        // Arrange
+        var hmacKey = Encoding.UTF8.GetBytes("test-key-12345678901234567890123456789012");
+        var salt = "test@example.com";
+        var range = 10;
+
+        // Act
+        var result1 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+        var result2 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(result1, result2);
+        Assert.InRange(result1, 0, range - 1);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_SameInputSameKey_AlwaysReturnsSameResult()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "consistent@example.com";
+        var range = 100;
+
+        // Act - Call multiple times
+        var results = new int[10];
+        for (var i = 0; i < 10; i++)
+        {
+            results[i] = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+        }
+
+        // Assert - All results should be identical
+        Assert.All(results, result => Assert.Equal(results[0], result));
+        Assert.All(results, result => Assert.InRange(result, 0, range - 1));
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_DifferentInputsSameKey_ReturnsDifferentResults()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt1 = "user1@example.com";
+        var salt2 = "user2@example.com";
+        var range = 100;
+
+        // Act
+        var result1 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt1, range);
+        var result2 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt2, range);
+
+        // Assert
+        Assert.NotEqual(result1, result2);
+        Assert.InRange(result1, 0, range - 1);
+        Assert.InRange(result2, 0, range - 1);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_DifferentKeysSameInput_ReturnsDifferentResults()
+    {
+        // Arrange
+        var hmacKey1 = RandomNumberGenerator.GetBytes(32);
+        var hmacKey2 = RandomNumberGenerator.GetBytes(32);
+        var salt = "test@example.com";
+        var range = 100;
+
+        // Act
+        var result1 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey1, salt, range);
+        var result2 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey2, salt, range);
+
+        // Assert
+        Assert.NotEqual(result1, result2);
+        Assert.InRange(result1, 0, range - 1);
+        Assert.InRange(result2, 0, range - 1);
+    }
+
+    [Theory]
+    [InlineData(1)]
+    [InlineData(2)]
+    [InlineData(5)]
+    [InlineData(10)]
+    [InlineData(100)]
+    [InlineData(1000)]
+    public void GetIndexForInputHash_VariousRanges_ReturnsValidIndex(int range)
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "test@example.com";
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.InRange(result, 0, range - 1);
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("   ")]
+    public void GetIndexForInputHash_EmptyString_HandlesGracefully(string salt)
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, 10);
+
+        // Assert
+        Assert.InRange(result, 0, 9);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_NullInput_ThrowsException()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        string salt = null;
+        var range = 10;
+
+        // Act & Assert
+        Assert.Throws<NullReferenceException>(() =>
+            EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range));
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_SpecialCharacters_HandlesCorrectly()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "test+user@example.com!@#$%^&*()";
+        var range = 50;
+
+        // Act
+        var result1 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+        var result2 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(result1, result2);
+        Assert.InRange(result1, 0, range - 1);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_UnicodeCharacters_HandlesCorrectly()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = "tëst@éxämplé.cöm";
+        var range = 25;
+
+        // Act
+        var result1 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+        var result2 = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.Equal(result1, result2);
+        Assert.InRange(result1, 0, range - 1);
+    }
+
+    [Fact]
+    public void GetIndexForInputHash_LongInput_HandlesCorrectly()
+    {
+        // Arrange
+        var hmacKey = RandomNumberGenerator.GetBytes(32);
+        var salt = new string('a', 1000) + "@example.com";
+        var range = 30;
+
+        // Act
+        var result = EnumerationProtectionHelpers.GetIndexForInputHash(hmacKey, salt, range);
+
+        // Assert
+        Assert.InRange(result, 0, range - 1);
+    }
+
+    #endregion
+}

test/Identity.IntegrationTest/RequestValidation/SendAccess/SendAccessGrantValidatorIntegrationTests.cs

@@ -1,10 +1,8 @@
 using Bit.Core;
-using Bit.Core.Auth.IdentityServer;
 using Bit.Core.Enums;
 using Bit.Core.Services;
 using Bit.Core.Tools.Models.Data;
 using Bit.Core.Tools.SendFeatures.Queries.Interfaces;
-using Bit.Core.Utilities;
 using Bit.Identity.IdentityServer.Enums;
 using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.IntegrationTestCommon.Factories;
@@ -13,16 +11,14 @@ using Duende.IdentityServer.Validation;
 using NSubstitute;
 using Xunit;
 
-namespace Bit.Identity.IntegrationTest.RequestValidation;
+namespace Bit.Identity.IntegrationTest.RequestValidation.SendAccess;
 
 // in order to test the default case for the authentication method, we need to create a custom one so we can ensure the
 // method throws as expected.
 internal record AnUnknownAuthenticationMethod : SendAuthenticationMethod { }
 
-public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory factory) : IClassFixture<IdentityApplicationFactory>
+public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory _factory) : IClassFixture<IdentityApplicationFactory>
 {
-    private readonly IdentityApplicationFactory _factory = factory;
-
     [Fact]
     public async Task SendAccessGrant_FeatureFlagDisabled_ReturnsUnsupportedGrantType()
     {
@@ -39,7 +35,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -70,7 +66,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -125,7 +121,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -154,7 +150,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -183,7 +179,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId);
 
         // Act
         var error = await client.PostAsync("/connect/token", requestBody);
@@ -225,7 +221,7 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, "password123");
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, "password123");
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -236,37 +232,4 @@ public class SendAccessGrantValidatorIntegrationTests(IdentityApplicationFactory
         Assert.Contains("access_token", content);
         Assert.Contains("Bearer", content);
     }
-
-    private static FormUrlEncodedContent CreateTokenRequestBody(
-        Guid sendId,
-        string password = null,
-        string sendEmail = null,
-        string emailOtp = null)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-        var parameters = new List<KeyValuePair<string, string>>
-        {
-            new(OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess),
-            new(OidcConstants.TokenRequest.ClientId, BitwardenClient.Send ),
-            new(OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess),
-            new("deviceType", ((int)DeviceType.FirefoxBrowser).ToString()),
-            new(SendAccessConstants.TokenRequest.SendId, sendIdBase64)
-        };
-
-        if (!string.IsNullOrEmpty(password))
-        {
-            parameters.Add(new(SendAccessConstants.TokenRequest.ClientB64HashedPassword, password));
-        }
-
-        if (!string.IsNullOrEmpty(emailOtp) && !string.IsNullOrEmpty(sendEmail))
-        {
-            parameters.AddRange(
-            [
-                new KeyValuePair<string, string>("email", sendEmail),
-                new KeyValuePair<string, string>("email_otp", emailOtp)
-            ]);
-        }
-
-        return new FormUrlEncodedContent(parameters);
-    }
 }

test/Identity.IntegrationTest/RequestValidation/SendAccess/SendAccessTestUtilities.cs

@@ -0,0 +1,45 @@
+using Bit.Core.Auth.IdentityServer;
+using Bit.Core.Enums;
+using Bit.Core.Utilities;
+using Bit.Identity.IdentityServer.Enums;
+using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
+using Duende.IdentityModel;
+
+namespace Bit.Identity.IntegrationTest.RequestValidation.SendAccess;
+
+public static class SendAccessTestUtilities
+{
+    public static FormUrlEncodedContent CreateTokenRequestBody(
+        Guid sendId,
+        string email = null,
+        string emailOtp = null,
+        string password = null)
+    {
+        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
+        var parameters = new List<KeyValuePair<string, string>>
+        {
+            new(OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess),
+            new(OidcConstants.TokenRequest.ClientId, BitwardenClient.Send),
+            new(SendAccessConstants.TokenRequest.SendId, sendIdBase64),
+            new(OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess),
+            new("device_type", "10")
+        };
+
+        if (!string.IsNullOrEmpty(email))
+        {
+            parameters.Add(new KeyValuePair<string, string>(SendAccessConstants.TokenRequest.Email, email));
+        }
+
+        if (!string.IsNullOrEmpty(emailOtp))
+        {
+            parameters.Add(new KeyValuePair<string, string>(SendAccessConstants.TokenRequest.Otp, emailOtp));
+        }
+
+        if (!string.IsNullOrEmpty(password))
+        {
+            parameters.Add(new KeyValuePair<string, string>(SendAccessConstants.TokenRequest.ClientB64HashedPassword, password));
+        }
+
+        return new FormUrlEncodedContent(parameters);
+    }
+}

test/Identity.IntegrationTest/RequestValidation/SendAccess/SendEmailOtpReqestValidatorIntegrationTests.cs

@@ -1,28 +1,16 @@
 using Bit.Core.Auth.Identity.TokenProviders;
-using Bit.Core.Auth.IdentityServer;
-using Bit.Core.Enums;
 using Bit.Core.Services;
 using Bit.Core.Tools.Models.Data;
 using Bit.Core.Tools.SendFeatures.Queries.Interfaces;
-using Bit.Core.Utilities;
-using Bit.Identity.IdentityServer.Enums;
-using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.IntegrationTestCommon.Factories;
 using Duende.IdentityModel;
 using NSubstitute;
 using Xunit;
 
-namespace Bit.Identity.IntegrationTest.RequestValidation;
+namespace Bit.Identity.IntegrationTest.RequestValidation.SendAccess;
 
-public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<IdentityApplicationFactory>
+public class SendEmailOtpRequestValidatorIntegrationTests(IdentityApplicationFactory _factory) : IClassFixture<IdentityApplicationFactory>
 {
-    private readonly IdentityApplicationFactory _factory;
-
-    public SendEmailOtpRequestValidatorIntegrationTests(IdentityApplicationFactory factory)
-    {
-        _factory = factory;
-    }
-
     [Fact]
     public async Task SendAccess_EmailOtpProtectedSend_MissingEmail_ReturnsInvalidRequest()
     {
@@ -43,7 +31,7 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId); // No email
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId); // No email
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -87,7 +75,7 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, sendEmail: email); // Email but no OTP
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, email: email); // Email but no OTP
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -130,7 +118,7 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, sendEmail: email, emailOtp: otp);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, email: email, emailOtp: otp);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -174,7 +162,7 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, sendEmail: email, emailOtp: invalidOtp);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, email: email, emailOtp: invalidOtp);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -216,7 +204,7 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, sendEmail: email); // Email but no OTP
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, email: email); // Email but no OTP
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -225,32 +213,4 @@ public class SendEmailOtpRequestValidatorIntegrationTests : IClassFixture<Identi
         var content = await response.Content.ReadAsStringAsync();
         Assert.Contains(OidcConstants.TokenErrors.InvalidRequest, content);
     }
-
-    private static FormUrlEncodedContent CreateTokenRequestBody(Guid sendId,
-    string sendEmail = null, string emailOtp = null)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-        var parameters = new List<KeyValuePair<string, string>>
-        {
-            new(OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess),
-            new(OidcConstants.TokenRequest.ClientId, BitwardenClient.Send ),
-            new(OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess),
-            new("deviceType", ((int)DeviceType.FirefoxBrowser).ToString()),
-            new(SendAccessConstants.TokenRequest.SendId, sendIdBase64)
-        };
-
-        if (!string.IsNullOrEmpty(sendEmail))
-        {
-            parameters.Add(new KeyValuePair<string, string>(
-                SendAccessConstants.TokenRequest.Email, sendEmail));
-        }
-
-        if (!string.IsNullOrEmpty(emailOtp))
-        {
-            parameters.Add(new KeyValuePair<string, string>(
-                SendAccessConstants.TokenRequest.Otp, emailOtp));
-        }
-
-        return new FormUrlEncodedContent(parameters);
-    }
 }

test/Identity.IntegrationTest/RequestValidation/SendAccess/SendNeverAuthenticateRequestValidatorTest.cs

@@ -0,0 +1,168 @@
+using Bit.Core.Services;
+using Bit.Core.Tools.Models.Data;
+using Bit.Core.Tools.SendFeatures.Queries.Interfaces;
+using Bit.Core.Utilities;
+using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
+using Bit.IntegrationTestCommon.Factories;
+using Duende.IdentityModel;
+using NSubstitute;
+using Xunit;
+
+namespace Bit.Identity.IntegrationTest.RequestValidation.SendAccess;
+
+public class SendNeverAuthenticateRequestValidatorIntegrationTests(
+    IdentityApplicationFactory _factory) : IClassFixture<IdentityApplicationFactory>
+{
+    /// <summary>
+    /// To support the static hashing function <see cref="EnumerationProtectionHelpers.GetIndexForInputHash"/> theses GUIDs and Key must be hardcoded
+    /// </summary>
+    private static readonly string _testHashKey = "test-key-123456789012345678901234567890";
+    // These Guids are static and ensure the correct index for each error type
+    private static readonly Guid _invalidSendGuid = Guid.Parse("1b35fbf3-a14a-4d48-82b7-2adc34fdae6f");
+    private static readonly Guid _emailSendGuid = Guid.Parse("bc8e2ef5-a0bd-44d2-bdb7-5902be6f5c41");
+    private static readonly Guid _passwordSendGuid = Guid.Parse("da36fa27-f0e8-4701-a585-d3d8c2f67c4b");
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_NoParameters_ReturnsInvalidSendId()
+    {
+        // Arrange
+        var client = ConfigureTestHttpClient(_invalidSendGuid);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(_invalidSendGuid);
+
+        // Act
+        var response = await client.PostAsync("/connect/token", requestBody);
+
+        // Assert
+        var content = await response.Content.ReadAsStringAsync();
+
+        Assert.Contains(OidcConstants.TokenErrors.InvalidGrant, content);
+
+        var expectedError = SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId;
+        Assert.Contains(expectedError, content);
+    }
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_ReturnsEmailRequired()
+    {
+        // Arrange
+        var client = ConfigureTestHttpClient(_emailSendGuid);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(_emailSendGuid);
+
+        // Act
+        var response = await client.PostAsync("/connect/token", requestBody);
+
+        // Assert
+        var content = await response.Content.ReadAsStringAsync();
+
+        // should be invalid grant
+        Assert.Contains(OidcConstants.TokenErrors.InvalidRequest, content);
+
+        // Try to compel the invalid email error
+        var expectedError = SendAccessConstants.EmailOtpValidatorResults.EmailRequired;
+        Assert.Contains(expectedError, content);
+    }
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_WithEmail_ReturnsEmailInvalid()
+    {
+        // Arrange
+        var email = "test@example.com";
+        var client = ConfigureTestHttpClient(_emailSendGuid);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(_emailSendGuid, email: email);
+
+        // Act
+        var response = await client.PostAsync("/connect/token", requestBody);
+
+        // Assert
+        var content = await response.Content.ReadAsStringAsync();
+
+        // should be invalid grant
+        Assert.Contains(OidcConstants.TokenErrors.InvalidGrant, content);
+
+        // Try to compel the invalid email error
+        var expectedError = SendAccessConstants.EmailOtpValidatorResults.EmailInvalid;
+        Assert.Contains(expectedError, content);
+    }
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_ReturnsPasswordRequired()
+    {
+        // Arrange
+        var client = ConfigureTestHttpClient(_passwordSendGuid);
+
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(_passwordSendGuid);
+
+        // Act
+        var response = await client.PostAsync("/connect/token", requestBody);
+
+        // Assert
+        var content = await response.Content.ReadAsStringAsync();
+
+        Assert.Contains(OidcConstants.TokenErrors.InvalidGrant, content);
+
+        var expectedError = SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired;
+        Assert.Contains(expectedError, content);
+    }
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_WithPassword_ReturnsPasswordInvalid()
+    {
+        // Arrange
+        var password = "test-password-hash";
+
+        var client = ConfigureTestHttpClient(_passwordSendGuid);
+
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(_passwordSendGuid, password: password);
+
+        // Act
+        var response = await client.PostAsync("/connect/token", requestBody);
+
+        // Assert
+        var content = await response.Content.ReadAsStringAsync();
+
+        Assert.Contains(OidcConstants.TokenErrors.InvalidRequest, content);
+
+        var expectedError = SendAccessConstants.PasswordValidatorResults.RequestPasswordDoesNotMatch;
+        Assert.Contains(expectedError, content);
+    }
+
+    [Fact]
+    public async Task SendAccess_NeverAuthenticateSend_ConsistentResponse_SameSendId()
+    {
+        // Arrange
+        var client = ConfigureTestHttpClient(_emailSendGuid);
+
+        var requestBody1 = SendAccessTestUtilities.CreateTokenRequestBody(_emailSendGuid);
+        var requestBody2 = SendAccessTestUtilities.CreateTokenRequestBody(_emailSendGuid);
+
+        // Act
+        var response1 = await client.PostAsync("/connect/token", requestBody1);
+        var response2 = await client.PostAsync("/connect/token", requestBody2);
+
+        // Assert
+        var content1 = await response1.Content.ReadAsStringAsync();
+        var content2 = await response2.Content.ReadAsStringAsync();
+
+        Assert.Equal(content1, content2);
+    }
+
+    private HttpClient ConfigureTestHttpClient(Guid sendId)
+    {
+        _factory.UpdateConfiguration(
+            "globalSettings:sendDefaultHashKey", _testHashKey);
+        return _factory.WithWebHostBuilder(builder =>
+        {
+            builder.ConfigureServices(services =>
+            {
+                var featureService = Substitute.For<IFeatureService>();
+                featureService.IsEnabled(Arg.Any<string>()).Returns(true);
+                services.AddSingleton(featureService);
+
+                var sendAuthQuery = Substitute.For<ISendAuthenticationQuery>();
+                sendAuthQuery.GetAuthenticationMethod(sendId)
+                    .Returns(new NeverAuthenticate());
+                services.AddSingleton(sendAuthQuery);
+            });
+        }).CreateClient();
+    }
+}

test/Identity.IntegrationTest/RequestValidation/SendAccess/SendPasswordRequestValidatorIntegrationTests.cs

@@ -1,28 +1,17 @@
-using Bit.Core.Auth.IdentityServer;
-using Bit.Core.Enums;
-using Bit.Core.KeyManagement.Sends;
+using Bit.Core.KeyManagement.Sends;
 using Bit.Core.Services;
 using Bit.Core.Tools.Models.Data;
 using Bit.Core.Tools.SendFeatures.Queries.Interfaces;
-using Bit.Core.Utilities;
-using Bit.Identity.IdentityServer.Enums;
 using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.IntegrationTestCommon.Factories;
 using Duende.IdentityModel;
 using NSubstitute;
 using Xunit;
 
-namespace Bit.Identity.IntegrationTest.RequestValidation;
+namespace Bit.Identity.IntegrationTest.RequestValidation.SendAccess;
 
-public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<IdentityApplicationFactory>
+public class SendPasswordRequestValidatorIntegrationTests(IdentityApplicationFactory _factory) : IClassFixture<IdentityApplicationFactory>
 {
-    private readonly IdentityApplicationFactory _factory;
-
-    public SendPasswordRequestValidatorIntegrationTests(IdentityApplicationFactory factory)
-    {
-        _factory = factory;
-    }
-
     [Fact]
     public async Task SendAccess_PasswordProtectedSend_ValidPassword_ReturnsAccessToken()
     {
@@ -54,7 +43,7 @@ public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, clientPasswordHash);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, password: clientPasswordHash);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -95,7 +84,7 @@ public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, wrongClientPasswordHash);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, password: wrongClientPasswordHash);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -131,7 +120,7 @@ public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId); // No password
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId); // No password
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -176,7 +165,7 @@ public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<Identi
             });
         }).CreateClient();
 
-        var requestBody = CreateTokenRequestBody(sendId, string.Empty);
+        var requestBody = SendAccessTestUtilities.CreateTokenRequestBody(sendId, string.Empty);
 
         // Act
         var response = await client.PostAsync("/connect/token", requestBody);
@@ -186,24 +175,4 @@ public class SendPasswordRequestValidatorIntegrationTests : IClassFixture<Identi
         Assert.Contains(OidcConstants.TokenErrors.InvalidRequest, content);
         Assert.Contains($"{SendAccessConstants.TokenRequest.ClientB64HashedPassword} is required", content);
     }
-
-    private static FormUrlEncodedContent CreateTokenRequestBody(Guid sendId, string passwordHash = null)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-        var parameters = new List<KeyValuePair<string, string>>
-        {
-            new(OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess),
-            new(OidcConstants.TokenRequest.ClientId, BitwardenClient.Send),
-            new(SendAccessConstants.TokenRequest.SendId, sendIdBase64),
-            new(OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess),
-            new("deviceType", "10")
-        };
-
-        if (passwordHash != null)
-        {
-            parameters.Add(new KeyValuePair<string, string>(SendAccessConstants.TokenRequest.ClientB64HashedPassword, passwordHash));
-        }
-
-        return new FormUrlEncodedContent(parameters);
-    }
 }

test/Identity.IntegrationTest/RequestValidation/VaultAccess/ResourceOwnerPasswordValidatorTests.cs

@@ -12,7 +12,7 @@ using Bit.Test.Common.Helpers;
 using Microsoft.AspNetCore.Identity;
 using Xunit;
 
-namespace Bit.Identity.IntegrationTest.RequestValidation;
+namespace Bit.Identity.IntegrationTest.RequestValidation.VaultAccess;
 
 public class ResourceOwnerPasswordValidatorTests : IClassFixture<IdentityApplicationFactory>
 {

test/Identity.Test/IdentityServer/SendAccess/SendAccessGrantValidatorTests.cs

@@ -1,12 +1,8 @@
-using System.Collections.Specialized;
-using Bit.Core;
+using Bit.Core;
 using Bit.Core.Auth.Identity;
-using Bit.Core.Auth.IdentityServer;
-using Bit.Core.Enums;
 using Bit.Core.Services;
 using Bit.Core.Tools.Models.Data;
 using Bit.Core.Tools.SendFeatures.Queries.Interfaces;
-using Bit.Core.Utilities;
 using Bit.Identity.IdentityServer.Enums;
 using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.Test.Common.AutoFixture;
@@ -81,7 +77,7 @@ public class SendAccessGrantValidatorTests
         var context = new ExtensionGrantValidationContext();
 
         tokenRequest.GrantType = CustomGrantTypes.SendAccess;
-        tokenRequest.Raw = CreateTokenRequestBody(Guid.Empty);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(Guid.Empty);
 
         // To preserve the CreateTokenRequestBody method for more general usage we over write the sendId
         tokenRequest.Raw.Set(SendAccessConstants.TokenRequest.SendId, "invalid-guid-format");
@@ -118,7 +114,9 @@ public class SendAccessGrantValidatorTests
     public async Task ValidateAsync_NeverAuthenticateMethod_ReturnsInvalidGrant(
         [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest,
         SutProvider<SendAccessGrantValidator> sutProvider,
-        Guid sendId)
+        NeverAuthenticate neverAuthenticate,
+        Guid sendId,
+        GrantValidationResult expectedResult)
     {
         // Arrange
         var context = SetupTokenRequest(
@@ -128,14 +126,20 @@ public class SendAccessGrantValidatorTests
 
         sutProvider.GetDependency<ISendAuthenticationQuery>()
             .GetAuthenticationMethod(sendId)
-            .Returns(new NeverAuthenticate());
+            .Returns(neverAuthenticate);
+
+        sutProvider.GetDependency<ISendAuthenticationMethodValidator<NeverAuthenticate>>()
+            .ValidateRequestAsync(context, neverAuthenticate, sendId)
+            .Returns(expectedResult);
 
         // Act
         await sutProvider.Sut.ValidateAsync(context);
 
         // Assert
-        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, context.Result.Error);
-        Assert.Equal($"{SendAccessConstants.TokenRequest.SendId} is invalid.", context.Result.ErrorDescription);
+        Assert.Equal(expectedResult, context.Result);
+        await sutProvider.GetDependency<ISendAuthenticationMethodValidator<NeverAuthenticate>>()
+            .Received(1)
+            .ValidateRequestAsync(context, neverAuthenticate, sendId);
     }
 
     [Theory, BitAutoData]
@@ -264,7 +268,7 @@ public class SendAccessGrantValidatorTests
     public void GrantType_ReturnsCorrectType()
     {
         // Arrange & Act
-        var validator = new SendAccessGrantValidator(null!, null!, null!, null!);
+        var validator = new SendAccessGrantValidator(null!, null!, null!, null!, null!);
 
         // Assert
         Assert.Equal(CustomGrantTypes.SendAccess, ((IExtensionGrantValidator)validator).GrantType);
@@ -289,44 +293,9 @@ public class SendAccessGrantValidatorTests
         var context = new ExtensionGrantValidationContext();
 
         request.GrantType = CustomGrantTypes.SendAccess;
-        request.Raw = CreateTokenRequestBody(sendId);
+        request.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId);
         context.Request = request;
 
         return context;
     }
-
-    private static NameValueCollection CreateTokenRequestBody(
-        Guid sendId,
-        string passwordHash = null,
-        string sendEmail = null,
-        string otpCode = null)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-
-        var rawRequestParameters = new NameValueCollection
-        {
-            { OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess },
-            { OidcConstants.TokenRequest.ClientId, BitwardenClient.Send },
-            { OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess },
-            { "deviceType", ((int)DeviceType.FirefoxBrowser).ToString() },
-            { SendAccessConstants.TokenRequest.SendId, sendIdBase64 }
-        };
-
-        if (passwordHash != null)
-        {
-            rawRequestParameters.Add(SendAccessConstants.TokenRequest.ClientB64HashedPassword, passwordHash);
-        }
-
-        if (sendEmail != null)
-        {
-            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Email, sendEmail);
-        }
-
-        if (otpCode != null && sendEmail != null)
-        {
-            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Otp, otpCode);
-        }
-
-        return rawRequestParameters;
-    }
 }

test/Identity.Test/IdentityServer/SendAccess/SendAccessTestUtilities.cs

@@ -0,0 +1,50 @@
+using System.Collections.Specialized;
+using Bit.Core.Auth.IdentityServer;
+using Bit.Core.Enums;
+using Bit.Core.Utilities;
+using Bit.Identity.IdentityServer.Enums;
+using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
+using Duende.IdentityModel;
+
+namespace Bit.Identity.Test.IdentityServer.SendAccess;
+
+public static class SendAccessTestUtilities
+{
+    public static NameValueCollection CreateValidatedTokenRequest(
+        Guid sendId,
+        string sendEmail = null,
+        string otpCode = null,
+        params string[] passwordHash)
+    {
+        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
+
+        var rawRequestParameters = new NameValueCollection
+        {
+            { OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess },
+            { OidcConstants.TokenRequest.ClientId, BitwardenClient.Send },
+            { OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess },
+            { "device_type", ((int)DeviceType.FirefoxBrowser).ToString() },
+            { SendAccessConstants.TokenRequest.SendId, sendIdBase64 }
+        };
+
+        if (sendEmail != null)
+        {
+            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Email, sendEmail);
+        }
+
+        if (otpCode != null && sendEmail != null)
+        {
+            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Otp, otpCode);
+        }
+
+        if (passwordHash != null && passwordHash.Length > 0)
+        {
+            foreach (var hash in passwordHash)
+            {
+                rawRequestParameters.Add(SendAccessConstants.TokenRequest.ClientB64HashedPassword, hash);
+            }
+        }
+
+        return rawRequestParameters;
+    }
+}

test/Identity.Test/IdentityServer/SendAccess/SendConstantsSnapshotTests.cs

@@ -31,9 +31,9 @@ public class SendConstantsSnapshotTests
     public void GrantValidatorResults_Constants_HaveCorrectValues()
     {
         // Assert
-        Assert.Equal("valid_send_guid", SendAccessConstants.GrantValidatorResults.ValidSendGuid);
-        Assert.Equal("send_id_required", SendAccessConstants.GrantValidatorResults.SendIdRequired);
-        Assert.Equal("send_id_invalid", SendAccessConstants.GrantValidatorResults.InvalidSendId);
+        Assert.Equal("valid_send_guid", SendAccessConstants.SendIdGuidValidatorResults.ValidSendGuid);
+        Assert.Equal("send_id_required", SendAccessConstants.SendIdGuidValidatorResults.SendIdRequired);
+        Assert.Equal("send_id_invalid", SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId);
     }
 
     [Fact]

test/Identity.Test/IdentityServer/SendAccess/SendEmailOtpRequestValidatorTests.cs

@@ -1,12 +1,7 @@
-using System.Collections.Specialized;
-using Bit.Core.Auth.Identity;
+using Bit.Core.Auth.Identity;
 using Bit.Core.Auth.Identity.TokenProviders;
-using Bit.Core.Auth.IdentityServer;
-using Bit.Core.Enums;
 using Bit.Core.Services;
 using Bit.Core.Tools.Models.Data;
-using Bit.Core.Utilities;
-using Bit.Identity.IdentityServer.Enums;
 using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.Test.Common.AutoFixture;
 using Bit.Test.Common.AutoFixture.Attributes;
@@ -28,7 +23,7 @@ public class SendEmailOtpRequestValidatorTests
         Guid sendId)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -61,8 +56,7 @@ public class SendEmailOtpRequestValidatorTests
         Guid sendId)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, email);
-        var emailOTP = new EmailOtp(["user@test.dev"]);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, email);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -96,7 +90,7 @@ public class SendEmailOtpRequestValidatorTests
         string generatedToken)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, email);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, email);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -144,7 +138,7 @@ public class SendEmailOtpRequestValidatorTests
         string email)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, email);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, email);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -179,7 +173,7 @@ public class SendEmailOtpRequestValidatorTests
         string otp)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, email, otp);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, email, otp);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -231,7 +225,7 @@ public class SendEmailOtpRequestValidatorTests
         string invalidOtp)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, email, invalidOtp);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, email, invalidOtp);
         var context = new ExtensionGrantValidationContext
         {
             Request = tokenRequest
@@ -278,33 +272,4 @@ public class SendEmailOtpRequestValidatorTests
         // Assert
         Assert.NotNull(validator);
     }
-
-    private static NameValueCollection CreateValidatedTokenRequest(
-        Guid sendId,
-        string sendEmail = null,
-        string otpCode = null)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-
-        var rawRequestParameters = new NameValueCollection
-        {
-            { OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess },
-            { OidcConstants.TokenRequest.ClientId, BitwardenClient.Send },
-            { OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess },
-            { "device_type", ((int)DeviceType.FirefoxBrowser).ToString() },
-            { SendAccessConstants.TokenRequest.SendId, sendIdBase64 }
-        };
-
-        if (sendEmail != null)
-        {
-            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Email, sendEmail);
-        }
-
-        if (otpCode != null && sendEmail != null)
-        {
-            rawRequestParameters.Add(SendAccessConstants.TokenRequest.Otp, otpCode);
-        }
-
-        return rawRequestParameters;
-    }
 }

test/Identity.Test/IdentityServer/SendAccess/SendNeverAuthenticateValidatorTests.cs

@@ -0,0 +1,280 @@
+using Bit.Core.Tools.Models.Data;
+using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
+using Bit.Test.Common.AutoFixture;
+using Bit.Test.Common.AutoFixture.Attributes;
+using Duende.IdentityModel;
+using Duende.IdentityServer.Validation;
+using Xunit;
+
+namespace Bit.Identity.Test.IdentityServer.SendAccess;
+
+[SutProviderCustomize]
+public class SendNeverAuthenticateRequestValidatorTests
+{
+    /// <summary>
+    /// To support the static hashing function <see cref="EnumerationProtectionHelpers.GetIndexForSaltHash"/> theses GUIDs and Key must be hardcoded
+    /// </summary>
+    private static readonly string _testHashKey = "test-key-123456789012345678901234567890";
+    // These Guids are static and ensure the correct index for each error type
+    private static readonly Guid _invalidSendGuid = Guid.Parse("1b35fbf3-a14a-4d48-82b7-2adc34fdae6f");
+    private static readonly Guid _emailSendGuid = Guid.Parse("bc8e2ef5-a0bd-44d2-bdb7-5902be6f5c41");
+    private static readonly Guid _passwordSendGuid = Guid.Parse("da36fa27-f0e8-4701-a585-d3d8c2f67c4b");
+
+    private static readonly NeverAuthenticate _authMethod = new();
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_GuidErrorSelected_ReturnsInvalidSendId(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_invalidSendGuid);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = _testHashKey;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _invalidSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, result.Error);
+        Assert.Equal(SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId, result.ErrorDescription);
+
+        var customResponse = result.CustomResponse as Dictionary<string, object>;
+        Assert.NotNull(customResponse);
+        Assert.Equal(
+            SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId, customResponse[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_EmailErrorSelected_HasEmail_ReturnsEmailInvalid(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest,
+        string email)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_emailSendGuid, sendEmail: email);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = _testHashKey;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _emailSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, result.Error);
+        Assert.Equal(SendAccessConstants.EmailOtpValidatorResults.EmailInvalid, result.ErrorDescription);
+
+        var customResponse = result.CustomResponse as Dictionary<string, object>;
+        Assert.NotNull(customResponse);
+        Assert.Equal(SendAccessConstants.EmailOtpValidatorResults.EmailInvalid, customResponse[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_EmailErrorSelected_NoEmail_ReturnsEmailRequired(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_emailSendGuid);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = _testHashKey;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _emailSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidRequest, result.Error);
+        Assert.Equal(SendAccessConstants.EmailOtpValidatorResults.EmailRequired, result.ErrorDescription);
+
+        var customResponse = result.CustomResponse as Dictionary<string, object>;
+        Assert.NotNull(customResponse);
+        Assert.Equal(SendAccessConstants.EmailOtpValidatorResults.EmailRequired, customResponse[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_PasswordErrorSelected_HasPassword_ReturnsPasswordDoesNotMatch(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest,
+        string password)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_passwordSendGuid, passwordHash: password);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = _testHashKey;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _passwordSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidRequest, result.Error);
+        Assert.Equal(SendAccessConstants.PasswordValidatorResults.RequestPasswordDoesNotMatch, result.ErrorDescription);
+
+        var customResponse = result.CustomResponse as Dictionary<string, object>;
+        Assert.NotNull(customResponse);
+        Assert.Equal(SendAccessConstants.PasswordValidatorResults.RequestPasswordDoesNotMatch, customResponse[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_PasswordErrorSelected_NoPassword_ReturnsPasswordRequired(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest)
+    {
+        // Arrange
+
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_passwordSendGuid);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = _testHashKey;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _passwordSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, result.Error);
+        Assert.Equal(SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired, result.ErrorDescription);
+
+        var customResponse = result.CustomResponse as Dictionary<string, object>;
+        Assert.NotNull(customResponse);
+        Assert.Equal(SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired, customResponse[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_NullHashKey_UsesEmptyKey(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_invalidSendGuid);
+        var context = new ExtensionGrantValidationContext { Request = tokenRequest };
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = null;
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _invalidSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, result.Error);
+        Assert.Contains(result.ErrorDescription, SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_EmptyHashKey_UsesEmptyKey(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(_invalidSendGuid);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = "";
+
+        // Act
+        var result = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, _invalidSendGuid);
+
+        // Assert
+        Assert.True(result.IsError);
+        Assert.Equal(OidcConstants.TokenErrors.InvalidGrant, result.Error);
+        Assert.Contains(result.ErrorDescription, SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_ConsistentBehavior_SameSendIdSameResult(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest,
+        Guid sendId)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = "consistent-test-key-123456789012345678901234567890";
+
+        // Act
+        var result1 = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, sendId);
+        var result2 = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, sendId);
+
+        // Assert
+        Assert.Equal(result1.ErrorDescription, result2.ErrorDescription);
+        Assert.Equal(result1.Error, result2.Error);
+
+        var customResponse1 = result1.CustomResponse as Dictionary<string, object>;
+        var customResponse2 = result2.CustomResponse as Dictionary<string, object>;
+        Assert.Equal(customResponse1[SendAccessConstants.SendAccessError], customResponse2[SendAccessConstants.SendAccessError]);
+    }
+
+    [Theory, BitAutoData]
+    public async Task ValidateRequestAsync_DifferentSendIds_CanReturnDifferentResults(
+        SutProvider<SendNeverAuthenticateRequestValidator> sutProvider,
+        [AutoFixture.ValidatedTokenRequest] ValidatedTokenRequest tokenRequest,
+        Guid sendId1,
+        Guid sendId2)
+    {
+        // Arrange
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId1);
+        var context = new ExtensionGrantValidationContext
+        {
+            Request = tokenRequest
+        };
+
+        sutProvider.GetDependency<Core.Settings.GlobalSettings>().SendDefaultHashKey = "different-test-key-123456789012345678901234567890";
+
+        // Act
+        var result1 = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, sendId1);
+        var result2 = await sutProvider.Sut.ValidateRequestAsync(context, _authMethod, sendId2);
+
+        // Assert - Both should be errors
+        Assert.True(result1.IsError);
+        Assert.True(result2.IsError);
+
+        // Both should have valid error types
+        var validErrors = new[]
+        {
+            SendAccessConstants.SendIdGuidValidatorResults.InvalidSendId,
+            SendAccessConstants.EmailOtpValidatorResults.EmailRequired,
+            SendAccessConstants.PasswordValidatorResults.RequestPasswordIsRequired
+        };
+        Assert.Contains(result1.ErrorDescription, validErrors);
+        Assert.Contains(result2.ErrorDescription, validErrors);
+    }
+
+    [Fact]
+    public void Constructor_WithValidGlobalSettings_CreatesInstance()
+    {
+        // Arrange
+        var globalSettings = new Core.Settings.GlobalSettings
+        {
+            SendDefaultHashKey = "test-key-123456789012345678901234567890"
+        };
+
+        // Act
+        var validator = new SendNeverAuthenticateRequestValidator(globalSettings);
+
+        // Assert
+        Assert.NotNull(validator);
+    }
+}

test/Identity.Test/IdentityServer/SendAccess/SendPasswordRequestValidatorTests.cs

@@ -1,12 +1,7 @@
-using System.Collections.Specialized;
-using Bit.Core.Auth.Identity;
-using Bit.Core.Auth.IdentityServer;
+using Bit.Core.Auth.Identity;
 using Bit.Core.Auth.UserFeatures.SendAccess;
-using Bit.Core.Enums;
 using Bit.Core.KeyManagement.Sends;
 using Bit.Core.Tools.Models.Data;
-using Bit.Core.Utilities;
-using Bit.Identity.IdentityServer.Enums;
 using Bit.Identity.IdentityServer.RequestValidators.SendAccess;
 using Bit.Test.Common.AutoFixture;
 using Bit.Test.Common.AutoFixture.Attributes;
@@ -28,7 +23,7 @@ public class SendPasswordRequestValidatorTests
         Guid sendId)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -58,7 +53,7 @@ public class SendPasswordRequestValidatorTests
         string clientPasswordHash)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, clientPasswordHash);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: clientPasswordHash);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -92,7 +87,7 @@ public class SendPasswordRequestValidatorTests
         string clientPasswordHash)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, clientPasswordHash);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: clientPasswordHash);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -130,7 +125,7 @@ public class SendPasswordRequestValidatorTests
         Guid sendId)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, string.Empty);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: string.Empty);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -163,7 +158,7 @@ public class SendPasswordRequestValidatorTests
     {
         // Arrange
         var whitespacePassword = "   ";
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, whitespacePassword);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: whitespacePassword);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -196,7 +191,7 @@ public class SendPasswordRequestValidatorTests
         // Arrange
         var firstPassword = "first-password";
         var secondPassword = "second-password";
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, firstPassword, secondPassword);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: [firstPassword, secondPassword]);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -229,7 +224,7 @@ public class SendPasswordRequestValidatorTests
         string clientPasswordHash)
     {
         // Arrange
-        tokenRequest.Raw = CreateValidatedTokenRequest(sendId, clientPasswordHash);
+        tokenRequest.Raw = SendAccessTestUtilities.CreateValidatedTokenRequest(sendId, passwordHash: clientPasswordHash);
 
         var context = new ExtensionGrantValidationContext
         {
@@ -268,30 +263,4 @@ public class SendPasswordRequestValidatorTests
         // Assert
         Assert.NotNull(validator);
     }
-
-    private static NameValueCollection CreateValidatedTokenRequest(
-        Guid sendId,
-        params string[] passwordHash)
-    {
-        var sendIdBase64 = CoreHelpers.Base64UrlEncode(sendId.ToByteArray());
-
-        var rawRequestParameters = new NameValueCollection
-        {
-            { OidcConstants.TokenRequest.GrantType, CustomGrantTypes.SendAccess },
-            { OidcConstants.TokenRequest.ClientId, BitwardenClient.Send },
-            { OidcConstants.TokenRequest.Scope, ApiScopes.ApiSendAccess },
-            { "device_type", ((int)DeviceType.FirefoxBrowser).ToString() },
-            { SendAccessConstants.TokenRequest.SendId, sendIdBase64 }
-        };
-
-        if (passwordHash != null && passwordHash.Length > 0)
-        {
-            foreach (var hash in passwordHash)
-            {
-                rawRequestParameters.Add(SendAccessConstants.TokenRequest.ClientB64HashedPassword, hash);
-            }
-        }
-
-        return rawRequestParameters;
-    }
 }