Capture the Fortress (CTF) 2020 Official Rules

This contest will consist of a set of challenges for participants to solve. Upon solving a challenge, the participant gets a flag (some secret string such as CTF{thisisaflag}). The participant submits it in exchange for points. At the end of the competition, the participant with most points wins. In case of a tie, the participant with the earlier submission of the last flag will be the winner. General information about CTFs can be found here.

Please read the rules carefully. By participating in the challenges, participants unconditionally accept these rules.

Registration and Participation

The CTF registration period begins on October 21st 10:00 CET and continues throughout the duration of the CTF until November 18, 2020 18:00 CET.

Participation in the CTF is free of charge without any purchase obligation and open to all (subject to conditions set below). To participate, it is necessary to register using a valid email address on

Participants may register only once. Ledger reserves the role of arbitrator on this point and may exclude any Participant suspected of having participated with several accounts.

Participants can work as a team. However, the prize will be awarded solely to the person whose email is listed on the registration. It is the sole responsibility of the registrant to distribute any potential winnings. Ledger takes no liability for the distribution of reward to other group members.

The participation in the present challenges by the same person with several different emails will be void.

Participation in the challenges implies the express and unreserved acceptance of the rules in all its stipulations as well as the laws and regulations applicable to contests in force in France.

In cases of suspected frauds and/or unfair participation, Ledger reserves the right to conduct any verification it deems necessary. Any established corrupt of fraudulent practice will result in an immediate and definitive disqualification of the Participant, final without notice.

Participation may be deemed ineligible if you do not comply with the modalities of participation as set forth in the rules. Any participation that is incomplete or inaccurate or that do not follow the procedure of the rules shall not be considered and so shall invalidate the entry.


The contest begins at 10:00 CET on October 28, 2020 and ends at 18:00 CET on November 18, 2020 (3 weeks).

Participants are responsible for determining the corresponding time zone in their respective country or region.


There will be a scoreboard where points will be assigned at the end of the competition based on the challenges that were completed. Each challenge will have an amount of points and winners will be selected based on the greatest number of points earned. In case of a tie, the participant with the earlier submission of the last flag will be the winner.

As stated above, participants that have not complied with the rules will be disqualified.

Prizes distribution

The ten awarded participants will be contacted on their registration email address within two days following the end of the CTF, i.e. until November 20th.

Rewards will be paid using Bitcoin (given the Coinhouse price index at the time of payment). You will be responsible for any tax implications related to the reward you receive, as determined by the laws of your jurisdiction of residence or citizenship.


To be eligible for a reward, you must:

Competition limitations

It’s strictly forbidden and subject to disqualification to:

Due to the nature of this CTF, hardware contention might become an issue for a few challenges. If this situation occurs, we might introduce a time-slot per participant to mitigate this.

In general, any participation must be fair and not fraudulent.

The Organizing Company reserves the right to definitively exclude from the present Game, any Participant:

In the event of exclusion of a Participant, he will be deprived of all his rights under these rules and in particular, those related to obtaining the Prize involved.

Finally, Ledger may decide to cancel the challenges if it appears that obvious fraud has occurred in any form whatsoever, including computerized in the context of participation in the challenges or the determination of the Winner. Personal information: All personal data collected in connection with the challenges shall be processed by Ledger for the purpose of participation in the challenges.

Ledger only keeps your personal data for as long as we need it for the purpose for which we hold your personal data, to meet your needs, or to comply with our legal obligations.

To determine the data retention period of your data, we use the following criteria: Pursuant to applicable laws and regulations relating to personal data, you shall have the right to access, oppose, correct and delete any data related to you. You may exercise this right at any time upon notice, enclosing a copy of your ID, to the following address:

Any Participants exercising their right to delete their data prior to the end of the challenges shall be deemed to have waived and withdrawn their participation. The present rules shall be governed by French law.

To be taken in account, any claims relating to the challenges must be made in writing, with details of the name, first name and personal details, to the following email address: no later than 30 days after the deadline for participation in the challenges.

In the event of disagreement on the application or the interpretation of the present rules, and in the absence of amicable agreement, any litigation will be submitted to the competent courts of the jurisdiction of the Court of Appeal of Paris.


Should any questions arise, please contact us at