diff --git a/specification/iothub/resource-manager/Microsoft.Devices/2017-07-01/iothub.json b/specification/iothub/resource-manager/Microsoft.Devices/2017-07-01/iothub.json
index 2fbe20a24164..5257ce40cb5e 100644
--- a/specification/iothub/resource-manager/Microsoft.Devices/2017-07-01/iothub.json
+++ b/specification/iothub/resource-manager/Microsoft.Devices/2017-07-01/iothub.json
@@ -76,18 +76,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -120,18 +112,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "in": "path",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub to create or update.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "iotHubDescription",
@@ -179,18 +163,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub to delete.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -273,11 +249,7 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "in": "path",
-            "description": "The name of the resource group that contains the IoT hubs.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           }
         ],
         "responses": {
@@ -314,18 +286,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -359,18 +323,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -407,18 +363,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "eventHubEndpointName",
@@ -462,18 +410,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "eventHubEndpointName",
@@ -519,18 +459,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "eventHubEndpointName",
@@ -576,18 +508,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "eventHubEndpointName",
@@ -632,18 +556,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -680,18 +596,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "jobId",
@@ -732,18 +640,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -820,18 +720,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           }
         ],
         "responses": {
@@ -868,18 +760,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "keyName",
@@ -920,18 +804,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "exportDevicesParameters",
@@ -974,18 +850,10 @@
             "$ref": "#/parameters/subscriptionId"
           },
           {
-            "name": "resourceGroupName",
-            "description": "The name of the resource group that contains the IoT hub.",
-            "in": "path",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceGroupName"
           },
           {
-            "name": "resourceName",
-            "in": "path",
-            "description": "The name of the IoT hub.",
-            "required": true,
-            "type": "string"
+            "$ref": "#/parameters/resourceName"
           },
           {
             "name": "importDevicesParameters",
@@ -1013,9 +881,359 @@
         },
         "deprecated": false
       }
+    },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Devices/IotHubs/{resourceName}/certificates": {
+      "get": {
+        "tags": [ "Certificates" ],
+        "summary": "Get the certificate list.",
+        "description": "Returns the list of certificates.",
+        "operationId": "Certificates_ListByIoTHub",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+          {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+          {
+            "$ref": "#/parameters/resourceName"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "The body contains all the certificate list.",
+            "schema": {
+              "$ref": "#/definitions/CertificateListDescription"
+            }
+          },
+          "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      }
+    },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Devices/IotHubs/{resourceName}/certificates/{certificateName}": {
+      "get": {
+        "tags": [ "Certificates" ],
+        "summary": "Get the certificate.",
+        "description": "Returns the certificate.",
+        "operationId": "Certificates_Get",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+          {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+          {
+            "$ref": "#/parameters/resourceName"
+          },
+          {
+            "$ref": "#/parameters/certificateName"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "The body contains the certificate.",
+            "schema": {
+              "$ref": "#/definitions/CertificateDescription"
+            }
+          },
+          "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      },
+      "put": {
+        "tags": [ "Certificates" ],
+        "summary": "Upload the certificate to the IoT hub.",
+        "description": "Adds new or replaces existing certificate.",
+        "operationId": "Certificates_CreateOrUpdate",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+          {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+          {
+            "$ref": "#/parameters/resourceName"
+          },
+          {
+            "$ref": "#/parameters/certificateName"
+          },
+          {
+            "name": "certificateDescription",
+            "in": "body",
+            "description": "The certificate body.",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/CertificateBodyDescription"
+            }
+          }
+        ],
+        "responses": {
+          "201": {
+            "description": "If certificate didn't exist creation was successful, the operation returns HTTP status code of 201 (OK).",
+            "schema": {
+              "$ref": "#/definitions/CertificateDescription"
+            }
+          },
+          "200": {
+            "description": "If certificate already exist and update was successful, the operation returns HTTP status code of 201 (OK).",
+            "schema": {
+              "$ref": "#/definitions/CertificateDescription"
+            }
+          },
+          "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      },
+      "delete": {
+        "tags": [ "Certificates" ],
+        "summary": "Delete an X509 certificate.",
+        "description": "Deletes an existing X509 certificate or does nothing if it does not exist.",
+        "operationId": "Certificates_Delete",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+          {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+          {
+            "$ref": "#/parameters/resourceName"
+          },
+          {
+            "$ref": "#/parameters/certificateName"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Certificate has been deleted."
+          },          
+          "204": {
+            "description": "Certificate does not exist."
+          },
+		  "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      }
+    },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Devices/IotHubs/{resourceName}/certificates/{certificateName}/generateVerificationCode": {
+      "post": {
+        "tags": [ "Certificates" ],
+        "summary": "Generate verification code for proof of posession flow.",
+        "description": "Generates verification code for proof of posession flow. The verifification code will be used to generate a leaf certificate.",
+        "operationId": "Certificates_GenerateVerificationCode",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+		  {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+		  {
+            "$ref": "#/parameters/resourceName"
+          },
+		  {
+            "$ref": "#/parameters/certificateName"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "The body contains the certificate.",
+            "schema": {
+              "$ref": "#/definitions/CertificateWithNonceDescription"
+            }
+          },
+          "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      }
+    },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Devices/IotHubs/{resourceName}/certificates/{certificateName}/verify": {
+      "post": {
+        "tags": [ "Certificates" ],
+        "summary": "Verify certificate's private key posession.",
+        "description": "Verifies the certificate's private key posession by providing the leaf cert issued by the verifying pre uploaded certificate.",
+        "operationId": "Certificates_Verify",
+        "parameters": [
+          {
+            "$ref": "#/parameters/api-version"
+          },
+          {
+            "$ref": "#/parameters/subscriptionId"
+          },
+          {
+            "$ref": "#/parameters/resourceGroupName"
+          },
+          {
+            "$ref": "#/parameters/resourceName"
+          },
+          {
+            "$ref": "#/parameters/certificateName"
+          },
+          {
+            "name": "certificateVerificationBody",
+            "in":"body",
+            "description":"The name of the certificate",
+            "required":true,
+            "schema": {
+              "$ref": "#/definitions/CertificateVerificationDescription"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "The body contains the certificate.",
+            "schema": {
+              "$ref": "#/definitions/CertificateDescription"
+            }
+          },
+          "default": {
+            "description": "DefaultErrorResponse",
+            "schema": {
+              "$ref": "#/definitions/ErrorDetails"
+            }
+          }
+        },
+        "deprecated": false
+      }
     }
   },
   "definitions": {
+	"CertificateVerificationDescription":{
+      "description": "The JSON-serialized leaf certificate",
+      "type": "object",
+      "properties": {
+        "certificate": {
+          "description": "base-64 representation of X509 certificate .cer file or just .pem file content.",
+          "type": "string"
+        }
+      }
+    },
+    "CertificateBodyDescription":{
+      "description": "The JSON-serialized X509 Certificate.",
+      "type": "object",
+      "properties": {
+        "certificate": {
+          "description": "base-64 representation of the X509 leaf certificate .cer file or just .pem file content.",
+          "type": "string"
+        }
+      }
+    },
+    "CertificateListDescription": {
+      "description": "The JSON-serialized array of Certificate objects.",
+      "type": "object",
+      "properties": {
+        "value": {
+          "description": "The array of Certificate objects.",
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/CertificateDescription"
+          }
+        }
+      }
+    },
+    "CertificateDescription": {
+      "description": "The X509 Certificate.",
+      "type": "object",
+      "properties": {
+		"properties" : {
+          "$ref": "#/definitions/CertificateProperties"
+		},
+		"id": {
+          "readOnly": true,
+          "type": "string",
+          "description": "The resource identifier."
+		},
+		"name": {
+          "description": "The name of the certificate.",
+          "type": "string",
+		  "readOnly": true
+        },
+	    "etag": {
+          "description": "The entity tag.",
+          "type": "string",
+		  "readOnly": true
+		},
+		"type": {
+          "readOnly": true,
+          "type": "string",
+          "description": "The resource type."
+        }
+      },
+	  "x-ms-azure-resource": true
+    },
+    "CertificateWithNonceDescription": {
+      "description": "The X509 Certificate.",
+      "type": "object",
+      "properties": {
+	    "properties" : {
+          "$ref": "#/definitions/CertificatePropertiesWithNonce"
+		},
+	    "id": {
+	      "readOnly": true,
+          "type": "string",
+          "description": "The resource identifier."
+        },
+	    "name": {
+          "description": "The name of the certificate.",
+          "type": "string",
+		  "readOnly": true
+        },
+	    "etag": {
+          "description": "The entity tag.",
+          "type": "string",
+		  "readOnly": true
+        },
+		"type": {
+          "readOnly": true,
+          "type": "string",
+          "description": "The resource type."
+        }
+	  },
+	  "x-ms-azure-resource": true
+    },
     "SharedAccessSignatureAuthorizationRule": {
       "description": "The properties of an IoT hub shared access policy.",
       "type": "object",
@@ -1063,6 +1281,91 @@
         "rights"
       ]
     },
+	"CertificateProperties":
+	{
+	  "description": "The description of an X509 CA Certificate.",
+	  "type": "object",
+	  "properties": {
+		"subject": {
+		  "description": "The certificate's subject name.",
+		  "type": "string",
+		  "readOnly": true
+		},
+		"expiry": {
+		  "description": "The certificate's expiration date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		},
+		"thumbprint": {
+		  "description": "The certificate's thumbprint.",
+		  "type": "string",
+		  "readOnly": true
+		},
+		"isVerified": {
+		  "description": "Determines wether certificate has been verified.",
+		  "type": "boolean",
+		  "readOnly": true
+		},
+		"created": {
+		  "description": "The certificate's create date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		},
+		"updated": {
+		  "description": "The certificate's last update date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		}
+	  }
+	},
+	"CertificatePropertiesWithNonce":
+	{
+	  "description": "The description of an X509 CA Certificate including the challenge nonce issued for the Proof-Of-Possession flow.",
+	  "type": "object",
+	  "properties": {
+		"subject": {
+		  "description": "The certificate's subject name.",
+		  "type": "string",
+		  "readOnly": true
+		},
+		"expiry": {
+		  "description": "The certificate's expiration date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		},
+		"thumbprint": {
+		  "description": "The certificate's thumbprint.",
+		  "type": "string",
+		  "readOnly": true
+		},
+		"isVerified": {
+		  "description": "Determines wether certificate has been verified.",
+		  "type": "boolean",
+		  "readOnly": true
+		},
+		"created": {
+		  "description": "The certificate's create date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		},
+		"updated": {
+		  "description": "The certificate's last update date and time.",
+		  "type": "string",
+		  "format": "date-time-rfc1123",
+		  "readOnly": true
+		},
+		"verificationCode": {
+		  "description": "The certificate's verification code that will be used for proof of posession.",
+		  "type": "string",
+		  "readOnly": true
+		}
+	  }
+	},
     "IotHubProperties": {
       "description": "The properties of an IoT hub.",
       "type": "object",
@@ -2138,6 +2441,28 @@
       "description": "The version of the API.",
       "required": true,
       "type": "string"
+    },
+	"resourceGroupName": {
+      "name": "resourceGroupName",
+      "description": "The name of the resource group that contains the IoT hub.",
+      "in": "path",
+      "required": true,
+      "type": "string"
+    },
+	"resourceName":{
+      "name": "resourceName",
+      "in": "path",
+      "description": "The name of the IoT hub.",
+      "required": true,
+      "type": "string"
+    },
+    "certificateName":{
+      "name": "certificateName",
+      "in":"path",
+      "description":"The name of the certificate",
+      "required":true,
+      "type":"string",
+      "pattern":"^[A-Za-z0-9-._]{1,64}$"
     }
   }
 }
\ No newline at end of file