diff options
Diffstat (limited to 'docs/SSLCERTS')
| -rw-r--r-- | docs/SSLCERTS | 73 |
1 files changed, 48 insertions, 25 deletions
diff --git a/docs/SSLCERTS b/docs/SSLCERTS index 7dada8fa3..89e5bb623 100644 --- a/docs/SSLCERTS +++ b/docs/SSLCERTS @@ -1,23 +1,46 @@ -Peer SSL Certificate Verification -================================= +SSL Certificate Verification +============================ -(NOTE: If libcurl was built with Schannel or Secure Transport support, then -this does not apply to you. Scroll down for details on how the OS-native -engines handle SSL certificates. If you're not sure, then run "curl -V" and -read the results. If the version string says "WinSSL" in it, then it was built -with Schannel support.) +SSL is TLS +---------- + +SSL is the old name. It is called TLS these days. + + +Native SSL +---------- + +If libcurl was built with Schannel or Secure Transport support (the native SSL +libraries included in Windows and Mac OS X), then this does not apply to +you. Scroll down for details on how the OS-native engines handle SSL +certificates. If you're not sure, then run "curl -V" and read the results. If +the version string says "WinSSL" in it, then it was built with Schannel +support. + +It is about trust +----------------- + +This system is about trust. In your local CA cert bundle you have certs from +*trusted* Certificate Authorities that you then can use to verify that the +server certificates you see are valid. They're signed by one of the CAs you +trust. + +Which CAs do you trust? You can decide to trust the same set of companies your +operating system trusts, or the set one of the known browsers trust. That's +basically trust via someone else you trust. You should just be aware that +modern operating systems and browsers are setup to trust *hundreds* of +companies and recent years several such CAs have been found untrustworthy. + +Certificate Verification +------------------------ libcurl performs peer SSL certificate verification by default. This is done by using CA cert bundle that the SSL library can use to make sure the peer's server certificate is valid. -If you communicate with HTTPS or FTPS servers using certificates that are -signed by CAs present in the bundle, you can be sure that the remote server -really is the one it claims to be. - -Until 7.18.0, curl bundled a severely outdated ca bundle file that was -installed by default. These days, the curl archives include no ca certs at -all. You need to get them elsewhere. See below for example. +If you communicate with HTTPS, FTPS or other TLS-using servers using +certificates that are signed by CAs present in the bundle, you can be sure +that the remote server really is the one it claims to be. If the remote server uses a self-signed certificate, if you don't install a CA cert bundle, if the server uses a certificate signed by a CA that isn't @@ -94,15 +117,15 @@ cert bundle, will cause SSL to report an error ("certificate verify failed") during the handshake and SSL will then refuse further communication with that server. -Peer SSL Certificate Verification with NSS -========================================== +Certificate Verification with NSS +--------------------------------- If libcurl was built with NSS support, then depending on the OS distribution, -it is probably required to take some additional steps to use the system-wide CA -cert db. RedHat ships with an additional module, libnsspem.so, which enables -NSS to read the OpenSSL PEM CA bundle. This library is missing in OpenSuSE, and -without it, NSS can only work with its own internal formats. NSS also has a new -[database format](https://wiki.mozilla.org/NSS_Shared_DB). +it is probably required to take some additional steps to use the system-wide +CA cert db. RedHat ships with an additional module, libnsspem.so, which +enables NSS to read the OpenSSL PEM CA bundle. This library is missing in +OpenSuSE, and without it, NSS can only work with its own internal formats. NSS +also has a new [database format](https://wiki.mozilla.org/NSS_Shared_DB). Starting with version 7.19.7, libcurl automatically adds the 'sql:' prefix to the certdb directory (either the hardcoded default /etc/pki/nssdb or the @@ -112,11 +135,11 @@ format your distribution provides, examine the default certdb location: cert9.db, key4.db, pkcs11.txt; filenames of older versions are cert8.db, key3.db, secmod.db. -Peer SSL Certificate Verification with Schannel and Secure Transport -==================================================================== +Certificate Verification with Schannel and Secure Transport +----------------------------------------------------------- -If libcurl was built with Schannel (Microsoft's TLS/SSL engine) or Secure -Transport (Apple's TLS/SSL engine) support, then libcurl will still perform +If libcurl was built with Schannel (Microsoft's native TLS engine) or Secure +Transport (Apple's native TLS engine) support, then libcurl will still perform peer certificate verification, but instead of using a CA cert bundle, it will use the certificates that are built into the OS. These are the same certificates that appear in the Internet Options control panel (under Windows) |