diff --git a/src/Api/Controllers/TwoFactorController.cs b/src/Api/Controllers/TwoFactorController.cs
index d252b949c..6adc60a03 100644
--- a/src/Api/Controllers/TwoFactorController.cs
+++ b/src/Api/Controllers/TwoFactorController.cs
@@ -67,6 +67,51 @@ namespace Bit.Api.Controllers
             return response;
         }
 
+        [HttpPost("get-yubikey")]
+        public async Task<TwoFactorYubiKeyResponseModel> GetYubiKey([FromBody]TwoFactorRequestModel model)
+        {
+            var user = await CheckPasswordAsync(model.MasterPasswordHash);
+            var response = new TwoFactorYubiKeyResponseModel(user);
+            return response;
+        }
+
+        [HttpPut("yubikey")]
+        [HttpPost("yubikey")]
+        public async Task<TwoFactorYubiKeyResponseModel> PutYubiKey(
+            [FromBody]UpdateTwoFactorYubicoOtpRequestModel model)
+        {
+            var user = await CheckPasswordAsync(model.MasterPasswordHash);
+            model.ToUser(user);
+
+            await ValidateYubiKeyAsync(user, nameof(model.Key1), model.Key1);
+            await ValidateYubiKeyAsync(user, nameof(model.Key2), model.Key2);
+            await ValidateYubiKeyAsync(user, nameof(model.Key3), model.Key3);
+            await ValidateYubiKeyAsync(user, nameof(model.Key4), model.Key4);
+            await ValidateYubiKeyAsync(user, nameof(model.Key5), model.Key5);
+
+            await _userService.UpdateTwoFactorProviderAsync(user, TwoFactorProviderType.YubiKey);
+            var response = new TwoFactorYubiKeyResponseModel(user);
+            return response;
+        }
+
+        public async Task ValidateYubiKeyAsync(User user, string name, string value)
+        {
+            if(string.IsNullOrWhiteSpace(value) || value.Length == 12)
+            {
+                return;
+            }
+
+            if(!await _userManager.VerifyTwoFactorTokenAsync(user, TwoFactorProviderType.YubiKey.ToString(), value))
+            {
+                await Task.Delay(2000);
+                throw new BadRequestException(name, $"{name} is invalid.");
+            }
+            else
+            {
+                await Task.Delay(500);
+            }
+        }
+
         [HttpPost("get-email")]
         public async Task<TwoFactorEmailResponseModel> GetEmail([FromBody]TwoFactorRequestModel model)
         {
@@ -74,7 +119,7 @@ namespace Bit.Api.Controllers
             var response = new TwoFactorEmailResponseModel(user);
             return response;
         }
-        
+
         [HttpPost("send-email")]
         public async Task SendEmail([FromBody]TwoFactorEmailRequestModel model)
         {
@@ -136,7 +181,7 @@ namespace Bit.Api.Controllers
                 await Task.Delay(2000);
                 throw new BadRequestException("MasterPasswordHash", "Invalid password.");
             }
-            
+
             return user;
         }
     }
diff --git a/src/Core/Identity/YubicoOtpTokenProvider.cs b/src/Core/Identity/YubicoOtpTokenProvider.cs
index 4ff9d6085..3c14b694a 100644
--- a/src/Core/Identity/YubicoOtpTokenProvider.cs
+++ b/src/Core/Identity/YubicoOtpTokenProvider.cs
@@ -32,7 +32,7 @@ namespace Bit.Core.Identity
 
         public Task<bool> ValidateAsync(string purpose, string token, UserManager<User> manager, User user)
         {
-            if(token.Length != 44)
+            if(string.IsNullOrWhiteSpace(token) || token.Length != 44)
             {
                 return Task.FromResult(false);
             }
@@ -45,7 +45,7 @@ namespace Bit.Core.Identity
                 return Task.FromResult(false);
             }
 
-            var client = new YubicoClient(_globalSettings.Yubico.ClientId, _globalSettings.Yubico.ClientId);
+            var client = new YubicoClient(_globalSettings.Yubico.ClientId, _globalSettings.Yubico.Key);
             var response = client.Verify(token);
             return Task.FromResult(response.Status == YubicoResponseStatus.Ok);
         }
diff --git a/src/Core/Models/Api/Request/TwoFactorRequestModels.cs b/src/Core/Models/Api/Request/TwoFactorRequestModels.cs
index a26b251d1..2ff139a7a 100644
--- a/src/Core/Models/Api/Request/TwoFactorRequestModels.cs
+++ b/src/Core/Models/Api/Request/TwoFactorRequestModels.cs
@@ -57,12 +57,75 @@ namespace Bit.Core.Models.Api
         public string Key4 { get; set; }
         public string Key5 { get; set; }
 
+        public User ToUser(User extistingUser)
+        {
+            var providers = extistingUser.GetTwoFactorProviders();
+            if(providers == null)
+            {
+                providers = new Dictionary<TwoFactorProviderType, TwoFactorProvider>();
+            }
+            else if(providers.ContainsKey(TwoFactorProviderType.YubiKey))
+            {
+                providers.Remove(TwoFactorProviderType.YubiKey);
+            }
+
+            providers.Add(TwoFactorProviderType.YubiKey, new TwoFactorProvider
+            {
+                MetaData = new Dictionary<string, string>
+                {
+                    ["Key1"] = FormatKey(Key1),
+                    ["Key2"] = FormatKey(Key2),
+                    ["Key3"] = FormatKey(Key3),
+                    ["Key4"] = FormatKey(Key4),
+                    ["Key5"] = FormatKey(Key5)
+                },
+                Enabled = true
+            });
+            extistingUser.SetTwoFactorProviders(providers);
+            return extistingUser;
+        }
+
+        private string FormatKey(string keyValue)
+        {
+            if(string.IsNullOrWhiteSpace(keyValue))
+            {
+                return null;
+            }
+
+            return keyValue.Substring(0, 12);
+        }
+
         public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
         {
             if(string.IsNullOrWhiteSpace(Key1) && string.IsNullOrWhiteSpace(Key2) && string.IsNullOrWhiteSpace(Key3) &&
                 string.IsNullOrWhiteSpace(Key4) && string.IsNullOrWhiteSpace(Key5))
             {
-                yield return new ValidationResult("A Key is required.", new string[] { nameof(Key1) });
+                yield return new ValidationResult("A key is required.", new string[] { nameof(Key1) });
+            }
+
+            if(!string.IsNullOrWhiteSpace(Key1) && Key1.Length < 12)
+            {
+                yield return new ValidationResult("Key 1 in invalid.", new string[] { nameof(Key1) });
+            }
+
+            if(!string.IsNullOrWhiteSpace(Key2) && Key2.Length < 12)
+            {
+                yield return new ValidationResult("Key 2 in invalid.", new string[] { nameof(Key2) });
+            }
+
+            if(!string.IsNullOrWhiteSpace(Key3) && Key3.Length < 12)
+            {
+                yield return new ValidationResult("Key 3 in invalid.", new string[] { nameof(Key3) });
+            }
+
+            if(!string.IsNullOrWhiteSpace(Key4) && Key4.Length < 12)
+            {
+                yield return new ValidationResult("Key 4 in invalid.", new string[] { nameof(Key4) });
+            }
+
+            if(!string.IsNullOrWhiteSpace(Key5) && Key5.Length < 12)
+            {
+                yield return new ValidationResult("Key 5 in invalid.", new string[] { nameof(Key5) });
             }
         }
     }
diff --git a/src/Core/Models/Api/Response/TwoFactor/TwoFactorYubiKeyResponseModel.cs b/src/Core/Models/Api/Response/TwoFactor/TwoFactorYubiKeyResponseModel.cs
index c2332aa59..bd87945c0 100644
--- a/src/Core/Models/Api/Response/TwoFactor/TwoFactorYubiKeyResponseModel.cs
+++ b/src/Core/Models/Api/Response/TwoFactor/TwoFactorYubiKeyResponseModel.cs
@@ -14,7 +14,7 @@ namespace Bit.Core.Models.Api
                 throw new ArgumentNullException(nameof(user));
             }
 
-            var provider = user.GetTwoFactorProvider(TwoFactorProviderType.Email);
+            var provider = user.GetTwoFactorProvider(TwoFactorProviderType.YubiKey);
             if(provider?.MetaData != null && provider.MetaData.Count > 0)
             {
                 Enabled = provider.Enabled;
@@ -29,7 +29,7 @@ namespace Bit.Core.Models.Api
                 }
                 if(provider.MetaData.ContainsKey("Key3"))
                 {
-                    Key1 = provider.MetaData["Key3"];
+                    Key3 = provider.MetaData["Key3"];
                 }
                 if(provider.MetaData.ContainsKey("Key4"))
                 {