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# Using Certificates

A certificate is the digital equivalent of an ID card. Just as you may have several ID cards for different purposes, such as a driver's licence, an employee ID card, or a credit card, you can have several different certificates that identify you for different purposes.

This section describes how to perform operations related to certificates.

In this section:

- Getting Your Own Certificate
- Checking Security for a Web Page
- Managing Certificates
- Managing Smart Cards and Other Security Devices
- Managing SSL/TLS Warnings and Settings
- Controlling Validation

# Getting Your Own Certificate

Much like a credit card or a driver's licence, a certificate is a form of identification you can use to identify yourself over the Internet and other networks. Like other commonly used personal IDs, a certificate is typically issued by an organisation with recognised authority to issue such identification. An organisation that issues certificates is called a certificate authority (CA).

You can obtain certificates that identify you from public CAs, from system administrators or special CAs within your organisation, or from web sites offering specialised services that require a means of identification more reliable that your name and password.

Just as the requirements for a driver's licence vary depending on the type of vehicle you want to drive, the requirements for obtaining a certificate vary depending on what you want to use it for. In some cases getting a certificate may be as easy as going to a web site, entering some personal information, and automatically downloading the certificate into your browser. In other cases you may have to go through more complicated procedures.

You can obtain a certificate today by visiting the URL for a certificate authority and following the on-screen instructions. For a list of certificate authorities issuing certificates recognised by &brandShortName;, see the online document Included Certificate List.

Once you obtain a certificate, it is automatically stored in a security device. Your browser comes with its own built-in Software Security Device. A security device can also be a piece of hardware, such as a smart card.

Like a driver's licence or a credit card, a certificate is a valuable form of identification that can be abused if it falls into the wrong hands. Once you've obtained a certificate that identifies you, you should protect it in two ways: by backing it up and by setting your master password.

When you first obtain a certificate, you may be prompted to back it up. If you haven't yet created a master password, you will be asked to create one.

For detailed information about backing up a certificate and setting your master password, see Your Certificates.

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# Checking Security for a Web Page

When you're viewing any web page, the lock icon near the lower-right corner of the window informs you whether the entire contents of the page was protected by encryption while it was being received by your computer:

| A closed lock means that the page was protected by encryption when it was received.
| An open lock means the page was not protected by encryption when it was received.
| A broken lock means that some or all of the elements within the page were not protected by encryption when the page was received, even though the outermost HTML page was encrypted.

For more details about the encryption status of the page when it was received, click the lock icon (or open the View menu, choose Page Info, and click the Security tab).

The Security tab for Page Info provides two kinds of information:

- The top half describes whether the web site displaying the page has been verified. (For information on certificate verification, see Controlling Validation.)
- The bottom half describes whether the contents of the page you are viewing is protected by encryption while in transit over the network.

Important: The lock icon describes only the encryption status of the page while it was being received by your computer. To be notified when you send or receive information without encryption, or to block potentially harmful mixed content, select the appropriate SSL/TLS warning and mixed content options. See Privacy & Security Preferences - SSL/TLS for details.

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# Managing Certificates

You can use the Certificate Manager to manage the certificates you have available. Certificates may be stored on your computer's hard disc or on smart cards or other security devices attached to your computer.

To open the Certificate Manager:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, click Certificates. (If no subcategories are visible, double-click Privacy & Security to expand the list.)
3. In the Manage Certificates section, click Manage Certificates. You see the Certificate Manager.

In this section:

- Managing Certificates that Identify You
- Managing Certificates that Identify People
- Managing Certificates that Identify Servers
- Managing Certificates that Identify Certificate Authorities
- Managing Certificates that Identify Others

## Managing Certificates that Identify You

When you first open the Certificate Manager, you'll notice that it has several tabs across the top of its window. The first tab is called Your Certificates, and it displays the certificates your browser or mail client has available that identify you. Your certificates are listed under the names of the organisations that issued them.

To perform an action on one or more certificates, click the entry for the certificate (or `Cmd` `Ctrl`-click to select more than one), then click one of the buttons at the bottom of the Certificate Manager window. Each of these buttons brings up another window that allows you to perform the action. Click the Help button in any window to obtain more information about using that window.

For more details on how to view and manage these certificates, see Your Certificates.

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## Managing Certificates that Identify People

When you compose a mail message, you can choose to attach your digital signature to it. A digital signature allows recipients of the message to verify that the message really comes from you and hasn't been tampered with since you sent it.

Every time you send a digitally signed message, your encryption certificate is automatically included with the message. This certificate allows the message recipients to send you encrypted messages.

One of the easiest ways to obtain someone else's encryption certificate is for that person to send you a digitally signed message. Certificate Manager automatically stores other people's certificates whenever they are received in this way.

To view all the certificates identifying other people that are available to the Certificate Manager, click the People tab at the top of the Certificate Manager window. You can send encrypted messages to anyone for whom a valid certificate is listed. Certificates are listed under the names of the organisations that issued them.

To perform an action on one or more certificates, click the entry for the certificate (or `Cmd` `Ctrl`-click to select more than one), then click one of the buttons at the bottom of the Certificate Manager window. Each of these buttons brings up another window that allows you to perform the action. Click the Help button in any window to obtain more information about using that window.

For more details on how to view and manage these certificates, see the description of the Certificate Manager's People tab.

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## Managing Certificates that Identify Servers

Some web sites and mail servers use certificates to identify themselves. Such identification is required before the server can encrypt information transferred between it and your computer (or vice versa), so that no one can read the data while in transit.

If the URL for a web site begins with `https://`, the web site has a certificate. If you visit such a web site and its certificate was issued by a CA that the Certificate Manager doesn't know about or doesn't trust, you will be asked whether you want to accept the web site's certificate. When you accept a new web site certificate, the Certificate Manager adds it to its list of web site certificates.

To view all the web site certificates available to your browser, click the Servers tab at the top of the Certificate Manager window.

To perform an action on one or more certificates, click the entry for the certificate (or `Cmd` `Ctrl`-click to select more than one), then click one of the buttons at the bottom of the Certificate Manager window. Each of these buttons brings up another window that allows you to perform the action. Click the Help button in any window to obtain more information about using that window.

For more details on how to view and manage these certificates, see the description of the Certificate Manager's Servers tab.

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## Managing Certificates that Identify Certificate Authorities

Like other commonly used forms of ID, a certificate is issued by an organisation with recognised authority to issue such identification. An organisation that issues certificates is called a certificate authority (CA). A certificate that identifies a CA is called a CA certificate.

Certificate Manager typically has many CA certificates on file. These CA certificates permit Certificate Manager to recognise and work with certificates issued by the corresponding CAs. However, the presence of a CA certificate in this list does not guarantee that the certificates it issues can be trusted. You or your system administrator must make decisions about what kinds of certificates to trust depending on your security needs.

To view all the CA certificates available to your browser, click the Authorities tab at the top of the Certificate Manager window.

To perform an action on one or more CA certificates, click the entry for the certificate (or `Cmd` `Ctrl`-click to select more than one), then click one of the buttons at the bottom of the Certificate Manager window. Each of these buttons brings up another window that allows you to perform the action. Click the Help button in any window to obtain more information about using that window.

For more details on how to view and manage these certificates, see the description of the Certificate Manager's Authorities tab.

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## Managing Certificates that Identify Others

To see all certificates that do not fit into any of the other categories, click the Others tab at the top of the Certificate Manager window.

For more details on how to view and manage these certificates, see the description of the Certificate Manager's Others tab.

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# Managing Smart Cards and Other Security Devices

A smart card is a small device, typically about the size of a credit card, that contains a microprocessor and is capable of storing information about your identity (such as your private keys and certificates) and performing cryptographic operations.

To use a smart card, you typically need to have a smart card reader (a piece of hardware) attached to your computer, as well as software on your computer that controls the reader.

A smart card is just one kind of security device. A security device (sometimes called a token) is a hardware or software device that provides cryptographic services and stores information about your identity. Use the Device Manager to work with smart cards and other security devices.

In this section:

- About Security Devices and Modules
- Using Security Devices
- Using Security Modules
- Enable FIPS Mode

## About Security Devices and Modules

The Device Manager displays a window that lists the available security devices. You can use the Device Manager to manage any security devices, including smart cards, that support the Public Key Cryptography Standard (PKCS) #11.

A PKCS #11 module (sometimes called a security module) controls one or more security devices in much the same way that a software driver controls an external device such as a printer or modem. If you are installing a smart card, you must install the PKCS #11 module for the smart card on your computer as well as connecting the smart card reader.

By default, the Device Manager controls two internal PKCS #11 modules that manage three security devices:

- &brandShortName; Internal PKCS #11 Module: Controls two security devices:
  - Generic Crypto Services: A special security device that performs all cryptographic operations required by the &brandShortName; Internal PKCS #11 Module.
  - Software Security Device: Stores your certificates and keys that aren't stored on external security devices, including any CA certificates that you may have installed in addition to those that come with the browser.
- Builtin Roots Module: Controls a special security device called the Builtin Object Token. This security device stores the default CA certificates that come with the browser.

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## Using Security Devices

The Device Manager allows you to perform operations on security devices. To open the Device Manager, follow these steps:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, click Certificates. (If no subcategories are visible, double-click Privacy & Security to expand the list.)
3. In the Certificates panel, click Manage Security Devices.

The Device Manager lists each available PKCS #11 module in boldface, and the security devices managed by each module below its name.

When you select a security device, information about it appears in the middle of the Device Manager window, and some of the buttons on the right side of the window become available. For example, if you select the Software Security Device, you can perform these actions:

- Click Login or Logout to log in or out of the Software Security Device. If you are logging in, you will be asked to supply the master password for the device. You must be logged into a security device before your browser software can use it to provide cryptographic services.
- Click Change Password to change the master password for the device.

You can perform these actions on most security devices. However, you cannot perform them on the Builtin Object Token or Generic Crypto Services, which are special devices that must normally be available at all times.

For more details, see Device Manager.

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## Using Security Modules

If you want to use a smart card or other external security device, you must first install the module software on your computer and, if necessary, connect any associated hardware. Follow the instructions that come with the hardware.

After a new module is installed on your computer, follow these steps to load it:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, click Certificates. (If no subcategories are visible, double-click Privacy & Security to expand the list.)
3. In the Certificates panel, click Manage Security Devices.
4. Click Load.
5. In the Load PKCS #11 Module dialogue box, click the Browse button, locate the module file, and click Open.
6. Fill in the Module Name field with the name of the module and click OK.

The new module will then show up in the list of modules with the name you assigned to it.

To unload a PKCS #11 module, select its name and click Unload.

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## Enable FIPS Mode

Federal Information Processing Standards Publications (FIPS PUBS) 140-1 is a US government standard for implementations of cryptographic modules—that is, hardware or software that encrypts and decrypts data or performs other cryptographic operations (such as creating or verifying digital signatures). Many products sold to the US government must comply with one or more of the FIPS standards.

To enable FIPS mode for the browser, you use the Device Manager:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, click Certificates. (If no subcategories are visible, double-click Privacy & Security to expand the list.)
3. In the Certificates panel, click Manage Devices.
4. Click the Enable FIPS button. When FIPS is enabled, the name NSS Internal PKCS #11 Module changes to NSS Internal FIPS PKCS #11 Module and the Enable FIPS button changes to Disable FIPS.

To disable FIPS-mode, click Disable FIPS.

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# Managing SSL/TLS Warnings and Settings

The Secure Sockets Layer (SSL) protocol allows your computer to exchange information with other computers on the Internet in encrypted form—that is, the information is scrambled while in transit so that no one else can make sense of it. SSL is also used to identify computers on the Internet by means of certificates.

The Transport Layer Security (TLS) protocol is a new standard based on SSL. The old SSL versions have been deprecated for security reasons and TLS is the only supported protocol. The default set of enabled TLS versions works for most people with current servers. However, in some circumstances system administrators or other knowledgeable people may wish to adjust the SSL/TLS settings to fine-tune them for special security needs or to account for limited capabilities of some legacy servers.

You shouldn't adjust the SSL/TLS settings for your browser unless you know what you're doing or have the assistance of someone else who does. If you do need to adjust them for some reason, follow these steps:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, select SSL/TLS. (If no subcategories are visible, double-click Privacy & Security to expand the list.)

For more details, see SSL/TLS Settings.

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# Controlling Validation

As discussed above under Get Your Own Certificate, a certificate is a form of identification, much like a driver's licence, that you can use to identify yourself over the Internet and other networks. However, also like a driver's licence, a certificate may expire or become invalid for some other reason. Therefore, your browser software needs to confirm the validity of any given certificate in some way before trusting it for identification purposes.

This section describes how Certificate Manager validates certificates and how to control that process. To understand the process, you should have some familiarity with public-key cryptography. If you are not familiar with the use of certificates, you should check with your system administrator before attempting to change any of your browser's certificate validation settings.

In this section:

- How Validation Works
- Configuring OCSP

## How Validation Works

Whenever you use or view a certificate stored by Certificate Manager, it takes several steps to verify the certificate. At a minimum, it confirms that the CA's digital signature on the certificate was created by a CA whose own certificate is (1) present in the Certificate Manager's list of available CA certificates and (2) marked as trusted for issuing the kind of certificate being verified.

If the CA certificate is not itself present, the certificate chain for the CA certificate must include a higher-level CA certificate that is present and correctly trusted. Certificate Manager also confirms that the certificate being verified is currently marked as trusted in the certificate store. If any one of these checks fails, Certificate Manager marks the certificate as unverified and won't recognise the identity it certifies.

A certificate can pass all these tests and still be compromised in some way; for example, the certificate may be revoked because an unauthorised person has gained access to the certificate's private key. A compromised certificate can allow an unauthorised person (or web site) to pretend to be the certificate owner.

One way to combat this threat would be for Certificate Manager to check a previously downloaded certificate revocation list (CRL) as part of the verification process. However, those lists may be large and need to be updated frequently in order to remain current and thus useful.

The preferred way to combat the threat of compromised certificates is to use a special server that supports the Online Certificate Status Protocol (OCSP). Such a server can answer client queries about individual certificates (see Configuring OCSP, below).

The server, called an OCSP responder, receives an updated CRL periodically from the CA that issues the certificates to be verified. You can configure Certificate Manager to submit a status request for a certificate to the OCSP responder, and the OCSP responder confirms whether the certificate is valid.

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## Configuring OCSP

The settings that control OCSP are part of Certificates preferences. To view Certificates preferences, follow these steps:

1. Open the &brandShortName; Edit menu and choose Preferences.
2. Under the Privacy & Security category, click Certificates. (If no subcategories are visible, double-click Privacy & Security to expand the list.)

For information about the OCSP options available, see Privacy & Security Preferences - Certificates, OCSP.

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