Bytecoin

Bytecoin is the first cryptocurrency created with CryptoNote technology. Bytecoin allows users to make absolutely anonymous money transfers through the CryptoNote algorithm. CryptoNote uses CryptoNote ring signatures to provide anonymous transactions and allows you to sign a message on behalf of a group.

The signature only proves the message was created by someone from the group, but all the possible signers are indistinguishable from each other. Even if outgoing transactions are untraceable, everyone may still be able to see the payments received and thus determine one's income.

By using a variation of the Diffie-Hellman exchange protocol, a receiver has multiple unique one-time addresses derived from his single public key. After funds are sent to these addresses they can only be redeemed by the receiver; and it would be impossible to cross-link these payments.