# Tag Info

0

This is part of how the notion of security is defined. In the definition, the adversary is an algorithm that produces a pair of messages, and then gets back (in return) a ciphertext. The adversary is then supposed to do something (predict whether the ciphertext is the encryption of the first message or the second message), but that's not relevant -- what ...

1

The adversary $\mathcal A$ is an entity (think of a computer program) designed to participate in the experiment $\operatorname{PrivK}^{\text{eav}}_{A,\Pi}$. So the adversary produces two messages, then is given the encryption of one of them, and has to guess which one it was. Of course, you can give the adversary other "ciphertexts" too, but this wouldn't ...

1

One problem is that keyboard keys may or may not be uniform. Look at the F and J keys - they may have a little dot of plastic to identify them with your fingertips. That little dot may make them heavier or lighter than other keys, affecting how they shake up in a hat. Some keyboards, like Das Keyboard, were built with different spring actions for different ...

0

Dice have been extremely well studied (having been used for gambling for, well, thousands of years). It is hard to beat them, for simplicity and bandwidth of random number generation, if you want to avoid use of computers for random number generation. Dice have three advantages. First, it's pretty fast to roll dice. Second, they are familiar; people ...

3

This is highly insecure. For instance, if you see the word guyk in the ciphertext, what could the corresponding plaintext word be? With your scheme (where each letter is enciphered by adding a number between 0..9 to it modulo 26), there are only 139 English words that could have led to it. (Those 139 possibilities are things like arse, blue, bore, both, ...

5

Firstly, I presume this is not something you are going to use for protecting data in any kind of real life scenario, but are only asking out of curiosity. Secondly, just to get the terminology straight and avoid confusion, what gives an OTP cryptographic scheme information theoretic security is that it meets both of the following two criteria: The key ...

Top 50 recent answers are included