Forum de mathématiques - Bibm@th.net

Bonjour,
Si quelqu'un peut m'aider à resoudre ce problème de criptographie.

merci d'expliquer en francais c'est plus compréhensible pour moi

merci c'est urgent

l'exercice est en anglais malheuresement:

1. AES-128 CTR misuse scenario
A block cipher such as AES-128 is usually used with a mode of operation. For this project we
will focus on the mode called CTR. The scenario of this project is the following: Alice and Bob
are exchanging messages using AES-128 CTR, however they are always using the same key and
initial value for the counter that is used in the CTR mode.
Here is an example of how Alice uses encryption to send messages to Bob using openssl command
line tool:
openssl enc -aes-128-ctr -kfile secret.key \
-nosalt -iv DEADBEEFCAFEBABEDEADBEEFCAFEBABE \
-in lorem.txt -a -out lorem.enc
File named secret.key contains the secret passphrase that Alice and Bob use to generate the
key. Files lorem.txt, lorem.enc and secret.key that were used for this example are available
with this project description.
In this scenario you do not know the key, but you know that Alice always uses the same value for
the -iv parameter (and all the options that she uses to call openssl are the same for each file that
she encrypts).

2. details

You will be given a zip file that contains a number of secret encrypted messages. Each message
is encrypted with the same secret key and your goal is to crack the code and obtain these secret
messages.
At the end of this project you should deliver a short report (maximum 6 pages excluding bibliographic
references and appendixes). Your report should contain:
1. short description of your code (diagrams) and implementation choices,
2. a description on how you obtained secret messages from ciphertexts (the vulnerability & the
security problem)