Shannons Definition of perfect Secrecy The One-Time pad E(m)=m⊕k ciphertext c One-Time pad k bits of random key K use random key sequence 9111011911 only once and then discard it 1001101010 1101000111Shannon‘s Definition of Perfect Secrecy m ciphertext C One-Time Pad k bits of random key K 1 0 0 1 1 0 1 0 1 0 0 1 1 1 0 1 1 0 1 1 1 1 0 1 0 0 0 1 1 1 use random key sequence only once and then discard it ! The One-Time Pad Ek (m) = m  k k