When you visit some ubuntu web sites, your browser may ask if you want to accept the certificate for the site.

"Examine Certificate" (Mozilla/Firefox) should say the fingerprints for the self-signed certificate are as follows:

Site: https://www.ubuntulinux.com/

• SHA1 Fingerprint B3:28:49:EE:5E:DB:42:AE:12:8D:D9:89:42:AC:6A:96:6E:BF:9A:90

• MD5 Fingerprint AB:0A:AB:3B:B8:E8:51:31:83:F0:4C:D6:EA:60:64:A0

Site: https://bugzilla.ubuntu.com/ or https://launchpad.ubuntu.com/

• SHA1 Fingerprint 68:07:9E:C6:62:73:0A:E2:7A:E5:0D:BA:9A:96:C3:6F:B8:01:16:B2

• MD5 Fingerprint 76:42:34:72:99:63:04:72:50:15:E3:4B:6A:80:48:9D

The recent discovery of collisions in SHA-1 and MD5 means you may want to confirm both hashes.