Never Skip Class Nor Squaring

hardware fault attacks FCSC 2022 solved on

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Description

You have access to a server that performs RSA signatures on arbitrary messages. During the connection, this server also sends you the encrypted flag that you need to decrypt.

The server is compromised and it is possible to inject glitchs to skip the square operations in the square and multiply algorithm used to perform the modular exponentiation of RSA.

Find the decryption key and recover the flag.

Note: Another similar challenge is available here: Never Skip Class Nor Multiplication.

Files

Author

Ker

Challenge Instructions

  1. First, download docker-compose.yml:
    curl https://hackropole.fr/challenges/fcsc2022-hardware-never-skip-class-nor-squaring/docker-compose.public.yml -o docker-compose.yml
  2. Launch the challenge by executing in the same folder:
    docker compose up
  3. Then, in another console, access the challenge with Netcat:
    nc localhost 4000
⚠️ Important: You must solve the challenge by interacting with the Docker container through the exposed network port. Any other way is not considered valid.

In case you encounter problems, please consult the FAQ.

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Writeups

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DateAuthor Language Tags Vote
2023-11-29
ribt
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