I found a lot about ring-signature but is it all that cryptonote is?
Could you help me to find all-in-one scheme with cryptonite and give any advantages or disadvantages of cryptonote in comparison with darkcoin?
P.S. Could you give me examples of the other anonymisation schemes using in altcoins (with altcoins example)
Cryptonote has multiple differences. Most notably, it's not the bitcoin protocol. The wallet and daemon have separate API's and you can run as many wallets as you want on one computer, with one daemon open. In addition to the ring signatures, it also provides stealth addressing.
It offers you a wide range of selections on the relative strength of the anonymity you desire, and is set by a mixin count. This lets you be 'more' or 'less' anonymous based on your own choosing.
Cryptonote also offers adaptive block sizing, which means that the set block size will scale to the number of transactions that people desire.
The functionality is different as well. Rather than having to set up a config file to solo mine, you can literally just open the daemon and wallet and type 'start_mining x'. Can't get any easier than that.
All transactions in cryptonote are capable of being revealed, and proven to have happened between two addresses, with input that those two transactors must supply separately. Without that information, payments are untraceable and unlinkable.
There are no rich lists. It has superior blockchain resistance to the bitcoin protocol.
It provides a smooth emission based on block number, which means that the block reward will decrease by a miniscule amount every single block. There is no day some time in the future when your block reward will suddenly drop to half, and you won't be left at the mercy of the net hash rate determining your block subsidy.
Advantages: Lots of people are telling you its gonna be worth a whole lot some day. Trustless anonymization scheme, requiring nothing more than a transaction fee to supply such anonymity. Provides adequate protection from unknown attackers with finite resources.
Disadvantages: Takes up a lot of space, unknown if prunable - it has taken years for coin with a pruned blockchain to show up so I'm hoping for the best - see cryptonite coin. Provides little to no protection from unknown attackers with infinite resources.
Anoncoin and some other PoS types are making a grab for anonymization as well. Anoncoin is attempting to implement zerocoin.