From Wikipedia, the free encyclopedia
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Jump to: navigation, search is a community-driven certificate authority that issues free public key certificates to the public.[1] CAcert has over 334,000 verified users and has issued over 1,285,000 certificates as of July 2016.[2]

These certificates can be used to digitally sign and encrypt email, authenticate and authorize users connecting to websites and secure data transmission over the Internet. Any application that supports the Secure Socket Layer (SSL) can make use of certificates signed by CAcert, as can any application that uses X.509 certificates, e.g. for encryption or code signing and document signatures.

CAcert Inc. Association[edit]

CAcert Inc. is an incorporated non-profit association registered[3] in New South Wales (Australia) since July 2003 which runs It has members living in many different countries and a board of 7 members.[4]

Robot CA[edit]

CAcert automatically signs certificates for email addresses which are verified as belonging to the requester and for domains for which certain email addresses (such as "") are verified as belonging to the requester. Thus it operates as a robot certificate authority. These certificates may be considered weak given the fact that CAcert does not emit any information in the certificates other than the domain name or email address (the CommonName field in X.509 certificates). However an argument can be made that domain verification is the only element within a certificate that can be trusted and proven, and that the domain name is the key element on which a user should base their trust. Extended Validation certificates on the other hand, in verifying the identity of the requesting party, may offer a false sense of security. The more important method of creating trust is that of verification of the domain itself.

Web of trust[edit]

To create higher-trust certificates, users can participate in a web of trust system whereby users physically meet and verify each other's identities. CAcert maintains the number of assurance points for each account. Assurance points can be gained through various means, primarily by having one's identity physically verified by users classified as "Assurers".

Having more assurance points allows users more privileges such as writing a name in the certificate and longer expiration times on certificates. A user with at least 100 assurance points is a Prospective Assurer, and may—after passing an Assurer Challenge[5]—verify other users; more assurance points allow the Assurer to assign more assurance points to others.

CAcert sponsors key signing parties, especially at big events such as CeBIT and FOSDEM.

Root certificate descriptions[edit]

Since October 2005, CAcert offers Class 1 and Class 3 root certificates. Class 3 is a high-security subset of Class 1.[6]

Inclusion status[edit]

As of May 2013, certificates issued by CAcert are not as useful in web browsers as certificates issued by commercial CAs such as VeriSign, because most installed web browsers do not distribute CAcert's root certificate.[7] Thus, for most web users, a certificate signed by CAcert behaves like a self-signed certificate. Discussion for inclusion of CAcert's root certificate in Mozilla and derivatives (such as Mozilla Firefox) started in 2004, when Mozilla had no CA certificate policy. Eventually, Mozilla developed that policy and CAcert withdrew its request for inclusion at the end of April 2007.[8] At the same time, the CA/Browser Forum was established and Extended Validation Certificates began to be issued. CAcert would need to improve their management system and deepen their formal verifications, auditing in particular. Progress toward this and a new request for inclusion can hardly be expected in the near future.[9] FreeBSD used to include the root certificate but removed it in 2008 following Mozilla's policy.[10] In 2014 it was removed from Ubuntu.[11]

The following operating systems or distributions include the CAcert root certificate, or have it available in an installable package:[7]

See also[edit]


  1. ^ About CAcert
  2. ^ CAcert usage statistics
  3. ^ CAcertInc - CAcert Wiki
  4. ^ CAcert Inc. Board of Directors
  5. ^ Assurance Policy, section 2.3.
  6. ^ FAQ/TechnicalQuestions - CAcert Wiki
  7. ^ a b CAcert inclusion status page
  8. ^ Discussion by Mozilla on including CAcert root certificate
  9. ^ CAcert audit comment on Mozilla
  10. ^ FreeBSD Security Officer (29 June 2008). "ca-roots". FreshPorts. Retrieved 16 December 2013. The ca_root_ns port basically makes no guarantees other than that the certificates comes from the Mozilla project. 
  11. ^ Luke Faraone (5 December 2013). "CAcert should not be trusted by default". Ubuntu Launchpad Bug report logs. Retrieved 14 March 2014. 
  12. ^ "Debian -- Details of package ca-cacert in sid". Retrieved 1 January 2016. 

External links[edit]