Many Time Pad

Coursera Cryptography 1

Week 1 homework

Many Time Pad
Let us see what goes wrong when a stream cipher key is used more than once. Below
are eleven hex-encoded ciphertexts that are the result of encrypting eleven plaintexts
with a stream cipher, all with the same stream cipher key. Your goal is to decrypt the last
ciphertext, and submit the secret message within it as solution.
Hint: XOR the ciphertexts together, and consider what happens when a space is XORed
with a character in [a-zA-Z].

text #1
we can factor the number 15 with quantum computers. we can also factor the number 15 with a do

text #2
euler would probably enjoy that now his theorem becomes a corner stone of crypto – Annonymous

text #3
the nice thing about Keeyloq is now we cryptographerS can drive a lot of fancy cars – Dan Bone

text #4
the ciphertext produced by a weak encryption algorithm looks as good as ciphertext produced by

text #5
you don’t want to buy a set of car keys from a guy who specializes in stealing cars – Marc Rot

text #6
there are two types of cryptograph so that which will keep secrets safe from your little sister

text #7
there are two types of cyptography: one that allows the government to use brute force to break

text #8
We can see the point where the chip is unhappy if a wrong bit is sent and consumes more power

text #9
a (private-key) encryption scheme states 3 algorithms, namely a procedure for generating keys

text #10
the concise oxforddictionary (2006) defi nes crypto as The art of writing o r solving codes.

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