diff --git a/src/lab/exp1/Introduction.html b/src/lab/exp1/Introduction.html index 84b1577..4ae1425 100644 --- a/src/lab/exp1/Introduction.html +++ b/src/lab/exp1/Introduction.html @@ -1,5 +1,6 @@ +
A private-key encryption scheme consists of a set of all possible messages, called the message space M, and three algorithms, namely, -
The algorithm for key generation Gen is used to choose a key k at random from the set of all possible secert keys, denoted by the key space K.
The algorithm for encryption Enc takes as inputs the message m and the secret key k and outputs the ciphertext c.
The algorithm for decryption Dec inputs the ciphertext c and the key k and outputs the message m.
Apparently, the system is easily broken if the total number of distinct secret keys is small, that is the key space K is small.
In this experiment, we work with a well-known historical encryption -scheme, namely the shift cipher, that has a very small key space.
Your task is to break the shift cipher. Specifically, given (only) -the ciphertext in some instance of a shift cipher, you need to find the -plaintext and the secret key.