Vanadium的小屋

Lecture 2

Attempts

Attempt 1

During the comunication, sk is totally secure

Attempt 2

During the comunication, msg is totally secure

Attempt 1 and 2 are difficult to keep secure

Attempt 3 / Shannon Privacy

During the comunication, the addversary CANNOT obtain ADDITIONAL information of the msg

1949 Shannon

Given $\pi = (Gen, Enc, Dec, M, K)$
$\forall t\in M, c\in C, Pr_{m\in D}[m=t]=Pr_{m\in D,sk\in Gen}[m=t|Enc(sk,m)=C]$

先验概率 = 后验概率 (看到密文后)

Attempt 4 / perfect

For any msg m, the distribution of the ciphertext is always identical