18
votes
Cracking Nested One-time Pads
Let $+$ and $-$ denote the "standard" arithmetic operations modulo 26 on the English alphabet, done letterwise to strings.
Here, encrypting text $T$ with a given one-time pad $P$ is simply ...
- 151k
7
votes
Cracking Nested One-time Pads
Using a Vigenere table with alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZ", using messages $C_{AB}$ and $C_B$ we can deduce key $A$.
Using the same table, since we have Key $A$ we can decode $C_A$ to get ...
- 13.6k
6
votes
Accepted
6 balls and a scale
I believe you're almost right in your assessment. Instead of
This is because each weighing
For this reason
- 2,973
6
votes
Accepted
Transfer of Information between two people
Each of you is kept in a cell with nothing but a button. When both buttons are pressed, the doors to both cells will open. Nothing will happen when only one button is pressed. Between the two cells is ...
- 8,596
5
votes
Accepted
IBM Research Puzzle – 5-ops implementation of erasure code
Posting a partial answer after clue 2:
Let's see then. (Doing binary operations in my head, so please forgive any errors.)
A number of the form $2^M -1$ is a string of "1" bits in binary, ...
- 80k
4
votes
Cracking Nested One-time Pads
The answer is
Let $m_i$ be the leter of the message, $a_i$ the letter of Alice pad and $b_i$ the leter of Bob pad. The first message is $m_i + a_i$, the second is $m_i + a_i +b_i$ and the third is $...
- 7,175
3
votes
Accepted
Cracking Nested One-time Pads
So there's already a bunch of answers that talk about how to get the "secret message" along with the one time pads, but none of them seem to point out:
The reason Alice decided to put the ...
- 342
3
votes
Judgment-free construction of a playlist
I've tried to anticipate some nitpicks at the process I present below. Nitpicks are in parentheses and set off from the main method. The core of the method can be found outside the parentheses.
Set-up ...
- 10.6k
3
votes
Judgment-free construction of a playlist
I have a proposed process, which has the downside of allowing for cheating, but works if both sides want to keep the information transfer within the outlined parameters:
This works because:
We can ...
- 3,625
2
votes
Ruins Game - Puzzle Edition
Partial answer - starting at the end:
We reveal...
Which we can then use to...
So the aim of this is to:
- 476
2
votes
How to encode Pi so it's recognizable as Pi?
I have to go now, so I expect to extend my answer when I shall return,
but a natural idea is
To avoid the decimal point encoding problem we can
- 1,057
1
vote
Accepted
Two Sheriffs and Eavesdroppers - 3
This was WAY easier than I expected.
Sheriff 1 can say something like "My list is one of {a,b}, {c,d}, and {e,f}."
Sheriff 2 can say "My list is one of {a,b} or {d,e}."
Case 1: ...
- 1,623
1
vote
Cracking Nested One-time Pads
Alice is using her pad $A$ twice, first to compute the value $C_A$, and then once more to compute $C_B$. The relationship between these values is known to Eve, who can exploit it to trivially recover ...
- 111
1
vote
Cracking Nested One-time Pads
I used some Python code to convert the encrypted messages to numbers, then subtracted them.
Answer
...
- 11
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