View source for Getting an SMIME certificate

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==Certificate Authorities==
===Sources of Free S/MIME Certificates===
Free certificates usable for [http://en.wikipedia.org/wiki/S/MIME S/MIME]  are available from:

*[https://www.actalis.it/products/certificates-for-secure-electronic-mail.aspx Actalis]
*[https://www.cacert.org/index.php?id=1 <S>CAcert</S>] (CAcert is NOT one of the trusted authorities built-in to FireFox and ThunderBird. The connection is also untrusted)
*[https://www.comodo.com/home/email-security/free-email-certificate.php <S>Comodo</S>]  (They've changed their name to Sectigo and no longer offer free S/MIME certificates/)
*[https://www.globalsign.com/document-security-compliance/microsoft-office-document-security/ <S>GlobalSign</S>] (No longer offer free certificates)
*[http://www.instantssl.com/ssl-certificate-products/free-email-certificate.html InstantSSL] (free certificate is now a 30 day trial)
*[https://www.secorio.com/index.php?S_MIME_Email_Certificates Secorio] (Affiliated Partner of Sectigo (formerly called Comodo) that links to InstantSSL if you want a free certificate)
*[https://cert.startcom.org/ <S>StartCom</S>] (StartCom certificates have been revoked by Mozilla) [https://blog.mozilla.org/security/2017/08/30/removing-disabled-wosign-startcom-certificates-firefox-58/]
*[https://www.wosign.com/english/Free_Email_Certificate.htm <S>Wosign</S>] (WoSign certificates have been revoked by Mozilla)

Currently only Actalis seems to offer a free S/MIME certificate for personal use that is good for one year. Everybody else appears to offer a free certificate for personal use for only 30 days, or require you to buy one. It can also cost money to revoke a free certificate. [http://www.techdirt.com/articles/20140409/11442426859/shameful-security-startcom-charges-people-to-revoke-ssl-certs-vulnerable-to-heartbleed.shtml]

Let's Encrypt does not currently offer S/MIME certificates. See https://community.letsencrypt.org/t/s-mime-certificates/153 for a thread explaining why you can't use their SSL/TLS certificates for S/MIME.

===To obtain certificate from an authority===
Firefox and Microsoft Internet Explorer contain cryptotools capable of generating public/private keypairs. When signing up for a certificate with an authority, their website triggers your browser to create a keypair and transmit to them the public key, which is then certified. For this reason, when you return to pick up your completed certificate (typically a few minutes later), it is mandatory that you do so with ''' ''the same browser on the same computer'' '''. You will otherwise not possess the private key necessary for pickup.

It will then still be necessary to export the resulting new key and certificate to a regular but password protected file that can then be imported into Thunderbird's certificate store. The CA's and/or your browsers help files should explain how to export your new certificate and keys.

To export it as a .p12 (Personal Information Exchange File) file using Firefox go to [[Menu differences in Windows, Linux, and Mac|Tools -> Options]] -> Advanced -> Encryption -> View Certificate and select the certificate. Then press the backup key. You will be prompted for a password which you will have to enter when you import the file. 

To import the file  into Thunderbird,  use "[[Menu differences in Windows, Linux, and Mac|Tools -> Options]] -> Advanced -> Encryption -> View Certificates -> Import". You will be prompted for the password you used when you exported (or backed up) the file.

Once you have imported your certificate into Thunderbird, it will be available for pairing with one or more accounts in Thunderbird using Tools -> Account Settings -> Security -> Select.

Be thoughtful about whether to select to "digitally sign all messages by default". Institutional firewalls may protect their own security protocols and break your cryptographic signature, leaving your recipient with all kinds of warnings about the message being invalidly signed. As S/MIME usage is still not widespread, most people still don't know how to interpret this. A broken signature will probably seem worse to them than receiving a message with no crypto signature at all, even though the contents are identical in both cases.

Webmail users will see an unreadable attachment which can raise similar questions.

==Self-signed certificates==
You may use a personally self-signed certificate in Thunderbird. However, since these certificates are not signed by an approved certificate authority, the certificate will not be trusted by other computers or people unless they add the self-signed certificate to their list of certificate authorities. Personally self-signed certificates are generally only useful for testing or for exchanging information with people you already know and trust.

It's possible to generate self-signed certificates using the Firefox Add-on [https://addons.mozilla.org/en-US/firefox/addon/4471 Key Manager]:
Tools - Key Manager Toolbox - Key Manager - Your Keys - Generate SelfSign Cert and insert you data. On tab Advanced - Standard X.509 Extensions check "Is CA?".

Another option for those who have sufficient understanding of certificate structures is using the command line. See [https://fam.tuwien.ac.at/~schamane/_/oldblog/140216_openssl_self-signed_certificates_thunderbird.html OpenSSL self-signed certificates & Thunderbird]

Special considerations for installing personally self-signed certificates can be found in the [[Installing an SMIME certificate]] article.

===Self-signed certificates in Mac OS X 10.4===
You can [http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh2139.html create your own self-signed certificate] using the ''Keychain Access'' application's ''Certificate Assistant''. To export your certificate as a PCKS12 file for import into Thunderbird, click "My Certificates" in the ''Keychain Access'' window. Select your self-signed certificate. Then from the menu bar select "File -> Export". You will be asked for a password to protect this file. This is the password you will require when importing the certificate into the "Your Certificates" tab of Thunderbird after entering your master password.

To export your certificate as a ".cer" file for use as a certificate authority, select "Certificates" in the ''Keychain Access'' window. Select your self-signed certificate. Then from the menu bar select "File -> Export". Be sure ".cer" is selected as the appropriate file type in the save dialog.

==Other uses for certificates==
Free certificates are not necessarily limited to use only by ''S/MIME'' email. The same digital id's can be imported and employed during document generation, for example, by ...
* ''Adobe Acrobat'' for signing and encrypting pdf documents. This requires the non-free ''Acrobat'' to generate. The free ''Adobe Reader'' is available to decrypt and verify.
* ''OpenOffice'' also contains some signing capability using certificates.
These have the advantage over ''S/MIME'' in that they pass more easily through firewalls, but at the price of requiring more steps to generate.

==See also==
* [[Installing an SMIME certificate | Installing an S/MIME certificate]]

==External links==
*[http://www.google.com/search?hl=en&q=Creating+a+self-signed+certificate+using+OpenSSL&btnG=Google+Search Creating a self-signed certificate using OpenSSL]
* [https://datatracker.ietf.org/doc/draft-ietf-acme-email-smime/ IETF draft on Extensions to Automatic Certificate Management Environment for end user S/MIME certificates]

[[Category:Privacy and security]]
[[Category:Privacy and security (Thunderbird)]]