Writeup For Flag Hunters

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Introduction to Flag Hunters

Flag Hunters is a challenging and exciting challenge in the PicoCTF2025 competition, designed to test the skills of participants in the realm of cryptography and problem-solving. In this writeup, we will delve into the details of the Flag Hunters challenge, providing a step-by-step guide on how to approach and solve it.

Understanding the Challenge

Flag Hunters is a web-based challenge that involves cracking a flag using a combination of cryptographic techniques and problem-solving skills. The challenge consists of a series of flags, each with its own unique encryption method. The goal is to crack each flag and submit the correct flag to earn points.

Initial Observations

Upon visiting the Flag Hunters challenge page, participants are presented with a simple web interface. The page displays a series of flags, each with a unique encryption method. The flags are displayed in a table format, with each flag having a unique ID, a flag name, and a encrypted flag value.

Identifying the Encryption Method

The first step in cracking the flags is to identify the encryption method used. Upon inspecting the encrypted flag values, participants may notice that the flags are encrypted using a combination of base64 encoding and AES encryption.

Base64 Encoding

Base64 encoding is a simple encoding scheme that converts binary data into a text format. In the case of Flag Hunters, the encrypted flag values are first encoded using base64. This encoding scheme is used to obfuscate the flag values, making it difficult for participants to identify the encryption method.

AES Encryption

AES encryption is a widely used symmetric-key block cipher that is used to encrypt the flag values. In the case of Flag Hunters, the AES encryption key is not provided, and participants must use their problem-solving skills to determine the key.

Cracking the Flags

To crack the flags, participants must use a combination of cryptographic techniques and problem-solving skills. The first step is to identify the AES encryption key, which can be done by analyzing the encrypted flag values and looking for patterns or clues.

Analyzing the Encrypted Flag Values

Upon analyzing the encrypted flag values, participants may notice that the flags are encrypted using a combination of AES encryption and a simple substitution cipher. The substitution cipher is used to replace each character in the flag value with a different character.

Determining the AES Encryption Key

Once the substitution cipher is identified, participants can use their problem-solving skills to determine the AES encryption key. This can be done by analyzing the encrypted flag values and looking for patterns or clues.

Cracking the Flag

Once the AES encryption key is determined, participants can use it to decrypt the flag values. This can be done using a combination of cryptographic techniques and programming languages such as Python or C++.

Submitting the Flag

Once the flag value is decrypted, participants can submit it to the Flag Hunters challenge page to earn points.

Conclusion

Flag Hunters is a challenging and exciting challenge in the PicoCTF2025 competition. By following the steps outlined in this writeup, participants can crack the flags and earn points. The challenge requires a combination of cryptographic techniques and problem-solving skills, making it a great way to test one's skills in the realm of cryptography and problem-solving.

Additional Resources

For those who want to learn more about cryptography and problem-solving, here are some additional resources:

  • Cryptography Tutorials: A series of tutorials on cryptography, covering topics such as AES encryption, base64 encoding, and substitution ciphers.
  • Problem-Solving Resources: A collection of resources on problem-solving, including tutorials, videos, and practice problems.
  • PicoCTF2025 Resources: A collection of resources on PicoCTF2025, including challenge writeups, tutorials, and practice problems.

Final Thoughts

Flag Hunters is a challenging and exciting challenge in the PicoCTF2025 competition. By following the steps outlined in this writeup, participants can crack the flags and earn points. The challenge requires a combination of cryptographic techniques and problem-solving skills, making it a great way to test one's skills in the realm of cryptography and problem-solving.

Introduction to Flag Hunters Q&A

In our previous article, we provided a comprehensive guide to the Flag Hunters challenge in PicoCTF2025. However, we understand that some participants may still have questions or need further clarification on certain aspects of the challenge. In this Q&A article, we will address some of the most frequently asked questions about Flag Hunters and provide additional information to help participants succeed in the challenge.

Q: What is the Flag Hunters challenge?

A: The Flag Hunters challenge is a web-based challenge in PicoCTF2025 that involves cracking a flag using a combination of cryptographic techniques and problem-solving skills. The challenge consists of a series of flags, each with its own unique encryption method.

Q: What is the objective of the Flag Hunters challenge?

A: The objective of the Flag Hunters challenge is to crack each flag and submit the correct flag to earn points. The challenge requires participants to use their problem-solving skills and knowledge of cryptography to determine the encryption method used for each flag.

Q: What are the encryption methods used in the Flag Hunters challenge?

A: The encryption methods used in the Flag Hunters challenge include base64 encoding and AES encryption. Participants must use their problem-solving skills to determine the encryption method used for each flag.

Q: How do I determine the AES encryption key?

A: To determine the AES encryption key, participants must analyze the encrypted flag values and look for patterns or clues. They can also use their knowledge of cryptography to identify the encryption method used and determine the key.

Q: What programming languages can I use to crack the flags?

A: Participants can use any programming language they are comfortable with to crack the flags. However, Python and C++ are popular choices for this challenge due to their ease of use and flexibility.

Q: Can I use online resources to help me crack the flags?

A: Yes, participants can use online resources such as tutorials, videos, and practice problems to help them crack the flags. However, they must ensure that they understand the concepts and techniques used in the challenge.

Q: How do I submit my flags?

A: Participants can submit their flags by visiting the Flag Hunters challenge page and entering the correct flag value in the designated field.

Q: What are the rules of the Flag Hunters challenge?

A: The rules of the Flag Hunters challenge are as follows:

  • Participants must crack each flag and submit the correct flag value to earn points.
  • Participants must use their problem-solving skills and knowledge of cryptography to determine the encryption method used for each flag.
  • Participants can use any programming language they are comfortable with to crack the flags.
  • Participants must ensure that they understand the concepts and techniques used in the challenge.

Q: What are the benefits of participating in the Flag Hunters challenge?

A: The benefits of participating in the Flag Hunters challenge include:

  • Gaining experience in cryptography and problem-solving.
  • Improving your skills in programming languages such as Python and C++.
  • Earning points and badges in PicoCTF2025.
  • Learning from your mistakes and improving your problem-solving skills.

Conclusion

The Flag Hunters challenge is a challenging and exciting challenge in PicoCTF2025 that requires participants to use their problem-solving skills and knowledge of cryptography to crack a series of flags. By following the steps outlined in this Q&A article, participants can gain a better understanding of the challenge and improve their chances of success.

Additional Resources

For those who want to learn more about cryptography and problem-solving, here are some additional resources:

  • Cryptography Tutorials: A series of tutorials on cryptography, covering topics such as AES encryption, base64 encoding, and substitution ciphers.
  • Problem-Solving Resources: A collection of resources on problem-solving, including tutorials, videos, and practice problems.
  • PicoCTF2025 Resources: A collection of resources on PicoCTF2025, including challenge writeups, tutorials, and practice problems.

Final Thoughts

The Flag Hunters challenge is a great way to test your skills in cryptography and problem-solving. By participating in this challenge, you can gain experience, improve your skills, and earn points and badges in PicoCTF2025. Good luck!