The developer of Cydia Saurik has been updated Cydia application
to 1.1.12 version with removes of 1.1.11 errors. So if you are using any
previous version of Cydia, Saurik recommended to install and use 1.1.12
version, because it has more bug fixes.
Cydia is not default application of your Device it is requires
jailbroken Device to install. Once jailbreak iOS with a proper jailbreak tool,
Cydia will install automatically. So there are not any method to download Cydia
except jailbreak.
Cydia is main part of Device, without using Cydia, users
cannot take full advantage because Cydia is allows to customize the Device as
user wish. With Apple store applications, iOS users are not allows to customize
the Device. There are common word in most of jailbreak related web sites, Cydia
can install without jailbreak. It is not a true. Cydia install requires jailbreak,
as highlighted above once jailbreak iOS, Cydia will install automatically.
For the jailbreak process need a proper jailbreak tool. It is
depend on Device model and iOS version. At the moment Pangu is an only proper
jailbreak tool.