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Manual Chapter: SSL Certificates for BIG-IP Devices
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SSL Certificates for BIG-IP Devices

About SSL digital certificates on the BIG-IP system

An SSL digital certificate is an electronic key pair that allows devices on a network to exchange data securely, using the public key infrastructure (PKI). PKI is based on public and private cryptographic key pairs used to encrypt and decrypt messages sent between two devices.

The BIG-IP® system uses digital certificates with the SSL/TLS protocol to grant authentication to clients on the external network that are generally untrusted. In high-security environments, the BIG-IP system can also use certificates to communicate securely with other systems on the internal network, such as web servers and other BIG-IP systems.

The BIG-IP system can sign a digital certificate in either of two ways:

  • By generating and submitting a request to a third-party trusted certificate authority (CA)
  • By creating a self-signed certificate. Self-signed certificates are typically used for testing purposes.

Once a certificate is installed or created on the BIG-IP system, other BIG-IP administrative users can specify those certificates in BIG-IP SSL profiles to manage SSL application traffic. Moreover, the BIG-IP system uses digital certificates to establish device trust in device service clustering (DSC™) configurations.

Supported certificate/key types

The BIG-IP® system supports multiple cipher suites when offloading SSL operations from a target server on the network. The BIG-IP system can support cipher suites that use these algorithms:

  • Rivest Shamir Adleman (RSA)
  • Elliptic Curve Digital Signature Algorithm (ECDSA)
  • Digital Signature Algorithm (DSA)

When you generate a certificate request or a self-signed certificate, you specify the type of private key, which determines that specific signing or encryption algorithm that is used to generate the private key.

About RSA certificates

RSA (Rivest Shamir Adleman) is the original encryption algorithm that is based on the concept of a public and a private key. When a public site attempts to communicate with a device such as the BIG-IP® system, the device sends the site a public key that the site uses to encrypt data before sending that data back to the device. The device uses its private key associated with the public key to decrypt the data. Only the device on which the certificate resides has access to this private key.

The RSA encryption algorithm includes an authentication mechanism.

About DSA certificates

DSA (Digital Signature Algorithm) uses a different algorithm for signing key exchange messages than that of RSA. DSA is paired with a key exchange method such as Diffie-Hellman or Elliptical Curve Diffie-Hellman to achieve a comparable level of security to RSA. Because DSA is generally endorsed by federal agencies, specifying a DSA key type makes it easier to comply with new government standards, such as those for specific key lengths.

About ECDSA certificates

When creating certificates on the BIG-IP® system, you can create a certificate with a key type of ECDSA (Elliptic Curve Digital Signature Algorithm). An ECDSA key is based on Elliptic Curve Cryptography (ECC), and provides better security and performance with significantly shorter key lengths.

For example, an RSA key size of 2048 bits is equivalent to an ECC key size of only 224 bits. As a result, less computing power is required, resulting in faster, more secure connections. Encryption based on ECC is ideally suited for mobile devices that cannot store large keys. The BIG-IP system supports both the prime256v1 and secp384r1 curve names, although only prime256v1 can be associated with an SSL profile.

About certificate management

You can obtain a certificate for the BIG-IP system by using the BIG-IP® Configuration utility to generate a certificate signing request (CSR) that can then be submitted to a third-party trusted certificate authority (CA). The CA then issues a signed certificate.

In addition to requesting CA-signed certificates, you can create self-signed certificates. You create self-signed certificates primarily for testing purposes within an organization.

When you install the BIG-IP software, the application includes a default self-signed certificate. The BIG-IP system also includes a default CA bundle certificate. This certificate bundle contains certificates from most of the well-known CAs.

Note: To manage digital certificates for the BIG-IP system, you must have a role of Certificate Manager, Administrator, or Resource Administrator assigned to your BIG-IP user account.

Creating a self-signed digital certificate

If you are configuring the BIG-IP® system to manage client-side HTTP traffic, you perform this task to create a self-signed certificate to authenticate and secure the client-side HTTP traffic. If you are also configuring the system to manage server-side HTTP traffic, you must repeat this task to create a second self-signed certificate to authenticate and secure the server-side HTTP traffic.
  1. On the Main tab, click System > File Management > SSL Certificate List .
    The SSL Certificate List screen opens.
  2. Click Create.
  3. In the Name field, type a unique name for the SSL certificate.
  4. From the Issuer list, select Self.
  5. In the Common Name field, type a name.
  6. In the Division field, type your company name.
  7. In the Organization field, type your department name.
  8. In the Locality field, type your city name.
  9. In the or State or Province field, type your state or province name.
  10. From the Country list, select the name of your country.
  11. In the E-mail Address field, type your email address.
  12. In the Lifetime field, type a number of days, or retain the default, 365.
  13. In the Subject Alternative Name field, type a name.
    This name is embedded in the certificate for X509 extension purposes.
    By assigning this name, you can protect multiple host names with a single SSL certificate.
  14. From the Key Type list, select a key type.
    Possible values are: RSA, DSA, and ECDSA.
  15. From the Size or Curve Name list, select either a size, in bits, or a curve name.
  16. If the BIG-IP system contains an internal HSM module, specify a location for storing the private key.
  17. Click Finished.

Requesting a certificate from a certificate authority

You perform this task to generate a certificate signing request (CSR) that can then be submitted to a third-party trusted certificate authority (CA).
  1. On the Main tab, click System > File Management > SSL Certificate List .
    The SSL Certificate List screen opens.
  2. Click Create.
  3. In the Name field, type a unique name for the SSL certificate.
  4. From the Issuer list, select Certificate Authority.
  5. In the Common Name field, type a name.
  6. In the Division field, type your company name.
  7. In the Organization field, type your department name.
  8. In the Locality field, type your city name.
  9. In the or State or Province field, type your state or province name.
  10. From the Country list, select the name of your country.
  11. In the E-mail Address field, type your email address.
  12. In the Lifetime field, type a number of days, or retain the default, 365.
  13. In the Subject Alternative Name field, type a name.
    This name is embedded in the certificate for X509 extension purposes.
    By assigning this name, you can protect multiple host names with a single SSL certificate.
  14. In the Challenge Password field, type a password.
  15. In the Confirm Password field, re-type the password you typed in the Challenge Password field.
  16. From the Key Type list, select a key type.
    Possible values are: RSA, DSA, and ECDSA.
  17. From the Size or Curve Name list, select either a size, in bits, or a curve name.
  18. If the BIG-IP system contains an internal HSM module, specify a location for storing the private key.
  19. Click Finished.
    The Certificate Signing Request screen displays.
  20. Do one of the following to download the request into a file on your system.
    • In the Request Text field, copy the certificate.
    • For Request File, click the button.
  21. Follow the instructions on the relevant certificate authority web site for either pasting the copied request or attaching the generated request file.
  22. Click Finished.
    The Certificate Signing Request screen displays.
The generated certificate signing request is submitted to a trusted certificate authority for signature.

Importing a certificate signed by a certificate authority

Before performing this task, confirm that a digital certificate signed by a certificate authority is available.
You can install an SSL certificate that is signed by a certificate authority by importing a certificate that already exists on the system hard drive. You can import a private key, a certificate or certificate bundle, or an archive.
  1. On the Main tab, click System > File Management > SSL Certificate List .
    The SSL Certificate List screen opens.
  2. Click Import.
  3. From the Import Type list, select Certificate.
  4. For the Certificate Name setting, do one of the following:
    • Select the Create New option, and type a unique name in the field.
    • Select the Overwrite Existing option, and select a certificate name from the list.
  5. For the Certificate Source setting, do one of the following:
    • Select the Upload File option, and browse to the location of the certificate file.
    • Select the Paste Text option, and paste the certificate text copied from another source.
  6. Click Import.
The SSL certificate that was signed by a certificate authority is installed.

Exporting a digital certificate

You perform this task to export a digital certificate to another device.
  1. On the Main tab, click System > File Management > SSL Certificate List .
    The SSL Certificate List screen opens.
  2. Click the name of the certificate you want to export.
    The General Properties screen displays.
  3. Click Export.
    The Certificate Export screen displays the contents of the certificate in the Certificate Text box.
  4. To obtain the certificate, do one of the following:
    • Copy the text from the Certificate Text field, and paste it as needed into an interface on another system.
    • At the Certificate File option, click Download filename where filename is the name of the certificate file, such as mycert.crt.

Viewing a list of certificates on the system

You can perform this task to view a list of existing digital certificates on the BIG-IP® system.

  1. On the Main tab, click System > File Management > SSL Certificate List .
    The SSL Certificate List screen opens.
  2. In the Name column, view the list of certificates on the system.

Digital certificate properties

When you use the BIG-IP® Configuration utility to view the list of digital certificates that you have installed on the BIG-IP® system, you can see information for each certificate.

Property Description
Certificate The name of the certificate.
Content The type of certificate content, for example, Certificate Bundle or Certificate and Key.
Common name The common name (CN) for the certificate. The common name embedded in the certificate is used for name-based authentication. The default common name for a self-signed certificate is localhost.localdomain.
Expiration date The date that the certificate expires. If the certificate is a bundle, this information shows the range of expiration dates that apply to certificates in the bundle.
Organization The organization name for the certificate. The organization name embedded in the certificate is used for name-based authentication. The default organization for a self-signed certificate is MyCompany.
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