Pem To X509

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Creates a new X509 certificate from the file contents of an RFC 7468 PEM-encoded certificate and private key. X509Certificate2.CreateFromPemFile(String, String) Method (System.Security.Cryptography.X509Certificates) Microsoft Docs. You can do this conversion with the OpenSSL library. Windows binaries can be found here. Once you have the library installed, the command you need to issue is: openssl x509 -in mycert.crt -out mycert.pem -outform PEM. In case you would 'check' it using openssl x509 -in chain.pem you will see just the first (in this case server) certificate. All the rest will be handled as comment - ignored. You have to separate it to extra file or just print specific line range via pipe to openssl to see the content. Azure IoT Hub authentication typically uses the PEM and PFX formats. Binary certificate. This contains a raw form binary certificate using DER ASN.1 Encoding. ASCII PEM format. A PEM certificate (.pem extension) contains a base64-encoded certificate beginning with -BEGIN CERTIFICATE- and ending with -END CERTIFICATE-.

However - this is a solved problem - case in point (openssl pkcs12 -in publicCert.pem -inkey privateKey.pem -export -out merged.pfx) The current solution creates an Immutable X509Certificate2 - as its constructor only the public key.

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X.509 certificates are digital documents that represent a user, computer, service, or device. They are issued by a certification authority (CA), subordinate CA, or registration authority and contain the public key of the certificate subject. They do not contain the subject's private key which must be stored securely. Public key certificates are documented by RFC 5280. They are digitally signed and, in general, contain the following information:

  • Information about the certificate subject
  • The public key that corresponds to the subject's private key
  • Information about the issuing CA
  • The supported encryption and/or digital signing algorithms
  • Information to determine the revocation and validity status of the certificate

Certificate fields

Over time there have been three certificate versions. Each version adds fields to the one before. Version 3 is current and contains version 1 and version 2 fields in addition to version 3 fields. Version 1 defined the following fields:

  • Version: A value (1, 2, or 3) that identifies the version number of the certificate
  • Serial Number: A unique number for each certificate issued by a CA
  • CA Signature Algorithm: Name of the algorithm the CA uses to sign the certificate contents
  • Issuer Name: The distinguished name (DN) of the certificate's issuing CA
  • Validity Period: The time period for which the certificate is considered valid
  • Subject Name: Name of the entity represented by the certificate
  • Subject Public Key Info: Public key owned by the certificate subject

Version 2 added the following fields containing information about the certificate issuer. These fields are, however, rarely used.

  • Issuer Unique ID: A unique identifier for the issuing CA as defined by the CA
  • Subject Unique ID: A unique identifier for the certificate subject as defined by the issuing CA

Version 3 certificates added the following extensions:

  • Authority Key Identifier: This can be one of two values:
    • The subject of the CA and serial number of the CA certificate that issued this certificate
    • A hash of the public key of the CA that issued this certificate
  • Subject Key Identifier: Hash of the current certificate's public key
  • Key Usage Defines the service for which a certificate can be used. This can be one or more of the following values:
    • Digital Signature
    • Non-Repudiation
    • Key Encipherment
    • Data Encipherment
    • Key Agreement
    • Key Cert Sign
    • CRL Sign
    • Encipher Only
    • Decipher Only
  • Private Key Usage Period: Validity period for the private key portion of a key pair
  • Certificate Policies: Policies used to validate the certificate subject
  • Policy Mappings: Maps a policy in one organization to policy in another
  • Subject Alternative Name: List of alternate names for the subject
  • Issuer Alternative Name: List of alternate names for the issuing CA
  • Subject Dir Attribute: Attributes from an X.500 or LDAP directory
  • Basic Constraints: Allows the certificate to designate whether it is issued to a CA, or to a user, computer, device, or service. This extension also includes a path length constraint that limits the number of subordinate CAs that can exist.
  • Name Constraints: Designates which namespaces are allowed in a CA-issued certificate
  • Policy Constraints: Can be used to prohibit policy mappings between CAs
  • Extended Key Usage: Indicates how a certificate's public key can be used beyond the purposes identified in the Key Usage extension
  • CRL Distribution Points: Contains one or more URLs where the base certificate revocation list (CRL) is published
  • Inhibit anyPolicy: Inhibits the use of the All Issuance Policies OID (2.5.29.32.0) in subordinate CA certificates
  • Freshest CRL: Contains one or more URLs where the issuing CA's delta CRL is published
  • Authority Information Access: Contains one or more URLs where the issuing CA certificate is published
  • Subject Information Access: Contains information about how to retrieve additional details for a certificate subject

Certificate formats

Certificates can be saved in a variety of formats. Azure IoT Hub authentication typically uses the PEM and PFX formats.

Binary certificate

This contains a raw form binary certificate using DER ASN.1 Encoding.

Openssl x509 pem to key

ASCII PEM format

A PEM certificate (.pem extension) contains a base64-encoded certificate beginning with -----BEGIN CERTIFICATE----- and ending with -----END CERTIFICATE-----. The PEM format is very common and is required by IoT Hub when uploading certain certificates.

ASCII (PEM) key

Pem To X509

Contains a base64-encoded DER key with possibly additional metadata about the algorithm used for password protection.

PKCS#7 certificate

A format designed for the transport of signed or encrypted data. It is defined by RFC 2315. It can include the entire certificate chain.

PKCS#8 key

The format for a private key store defined by RFC 5208.

PKCS#12 key and certificate

A complex format that can store and protect a key and the entire certificate chain. It is commonly used with a .pfx extension. PKCS#12 is synonymous with the PFX format.

For more information

For more information, see the following topics:

Next steps

If you want to generate test certificates that you can use to authenticate devices to your IoT Hub, see the following topics:

If you have a certification authority (CA) certificate or subordinate CA certificate and you want to upload it to your IoT hub and prove that you own it, see Proving Possession of a CA Certificate.

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IoT Central supports both shared access signatures (SAS) and X.509 certificates to secure the communication between a device and your application. The Create and connect a client application to your Azure IoT Central application tutorial uses SAS. In this article, you learn how to modify the code sample to use X.509. X.509 certificates are recommended in production environments. For more information, see Get connected to Azure IoT Central.

This article shows two ways of using X.509 - group enrollments typically used in a production environment, and individual enrollments useful for testing.

The code snippets in this article use JavaScript. For code samples in other languages, see:

Prerequisites

  • Completion of Create and connect a client application to your Azure IoT Central application (JavaScript) tutorial.
  • Git.
  • Download and install OpenSSL. If you're using Windows, you can use the binaries from the OpenSSL page on SourceForge.

Use a group enrollment

Use X.509 certificates with a group enrollment in a production environment. In a group enrollment, you add a root or intermediate X.509 certificate to your IoT Central application. Devices with leaf certificates derived from the root or intermediate certificate can connect to your application.

Generate root and device cert

In this section, you use an X.509 certificate to connect a device with a cert derived from the enrollment group's cert, which can connect to your IoT Central application.

Warning

This way of generating X.509 certs is for testing only. For a production environment you should use your official, secure mechanism for certificate generation.

  1. Open a command prompt. Clone the GitHub repository for the certificate generation scripts:

  2. Navigate to the certificate generator script and install the required packages:

  3. Create a root certificate and then derive a device certificate by running the script:

    Tip

    A device ID can contain letters, numbers, and the - character.

These commands produce three files each for the root and the device certificate

filenamecontents
<name>_cert.pemThe public portion of the X509 certificate
<name>_key.pemThe private key for the X509 certificate
<name>_fullchain.pemThe entire keychain for the X509 certificate.

Create a group enrollment

  1. Open your IoT Central application and navigate to Administration in the left pane and select Device connection.

  2. Select + Create enrollment group, and create a new enrollment group called MyX509Group with an attestation type of Certificates (X.509).

  3. Open the enrollment group you created and select Manage Primary.

  4. Select file option and upload the root certificate file called mytestrootcert_cert.pem that you generated previously:

  5. To complete the verification, generate the verification code, copy it, and then use it to create an X.509 verification certificate at the command prompt:

  6. Upload the signed verification certificate verification_cert.pem to complete the verification:

You can now connect devices that have an X.509 certificate derived from this primary root certificate.

After you save the enrollment group, make a note of the ID Scope.

Run sample device code

  1. Copy the sampleDevice01_key.pem and sampleDevice01_cert.pem files to the azure-iot-sdk-node/device/samples/pnp folder that contains the simple_thermostat.js application. You used this application when you completed the Connect a device (JavaScript) tutorial.

  2. Navigate to the azure-iot-sdk-node/device/samples/pnp folder that contains the simple_thermostat.js application and run the following command to install the X.509 package:

  3. Open the simple_thermostat.js file in a text editor.

  4. Edit the require statements to include the following:

  5. Add the following four lines to the 'DPS connection information' section to initialize the deviceCert variable:

  6. Edit the provisionDevice function that creates the client by replacing the first line with the following:

  7. In the same function, modify the line that sets the deviceConnectionString variable as follows:

  8. In the main function, add the following line after the line that calls Client.fromConnectionString:

  9. In your shell environment, set the following two environment variables:

    Tip

    You set the other required environment variables when you completed the Create and connect a client application to your Azure IoT Central application tutorial.

  10. Execute the script and verify the device was provisioned successfully:

    You can also verify that telemetry appears on the dashboard.

Use an individual enrollment

Use X.509 certificates with an individual enrollment to test your device and solution. In an individual enrollment, there's no root or intermediate X.509 certificate in your IoT Central application. Devices use a self-signed X.509 certificate to connect to your application.

Generate self-signed device cert

In this section, you use a self-signed X.509 certificate to connect devices for individual enrollment, which are used to enroll a single device. Self-signed certificates are for testing only.

Create a self-signed X.509 device certificate by running the script. Be sure to only use lower-case alphanumerics and hyphens for certificate name:

PemPem

Create individual enrollment

  1. In the Azure IoT Central application, select Devices, and create a new device with Device ID as mytestselfcertprimary from the thermostat device template. Make a note of the ID Scope, you use it later.

  2. Open the device you created and select Connect.

  3. Select Individual Enrollments as the Connect Method and Certificates (X.509) as the mechanism:

  4. Select file option under primary and upload the certificate file called mytestselfcertprimary_cert.pem that you generated previously.

  5. Select the file option for the secondary certificate and upload the certificate file called mytestselfcertsecondary_cert.pem. Then select Save:

The device is now provisioned with X.509 certificate.

Run a sample individual enrollment device

  1. Copy the mytestselfcertprimary_key.pem and mytestselfcertprimary_cert.pem files to the azure-iot-sdk-node/device/samples/pnp folder that contains the simple_thermostat.js application. You used this application when you completed the Connect a device (JavaScript) tutorial.

  2. Modify the environment variables you used in the sample above as follows:

  3. Execute the script and verify the device was provisioned successfully:

    You can also verify that telemetry appears on the dashboard.

You can repeat the above steps for mytestselfcertsecondary certificate as well.

Next steps

X509cert To Pem

Now that you've learned how to connect devices using X.509 certificates, the suggested next step is to learn how to Monitor device connectivity using Azure CLI