Korea has been in an uproar about privacy. One of the alternatives is Telegram.
South Korea Rumor Crackdown Jolts Social Media Users
KaokoTalk vows to protect user privacy
Surveillance drives South Koreans to Encrypted Messaging
One article says Telegram will not protect your messages against law enforcement eavesdropping or server compromise Telegram refutes this with Mobile Protocol: Telegram Beyond me. Telegram FAQ