IND-EAV

• indistinguishable under eavesdropping if there exists no PPT-bounded adversary with a non-negligible advantage of winning the EAV game. if no such strategy exists, then the encryption system does not leak any practically usable information.

  just by looking at the messages sent back and forth, can we tell what the message is?

• interested in what the adversary can learn from eavesdropping, if the ciphertexts are indistinguishable
• The adversary isn't trying to be correct every time, just with greater than negligible advantage (we'll define what we mean by negligible in the next lecture).