Introduction to Cryptography

Room

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Task 1 Introduction

You can guess that it is a quote. Who said it?

Miyamoto Musashi

Task 2 Symmetric Encryption

Decrypt the file quote01 encrypted (using AES256) with the key s!kR3T55 using gpg. What is the third word in the file?

waste

Decrypt the file quote02 encrypted (using AES256-CBC) with the key s!kR3T55 using openssl. What is the third word in the file?

science

Decrypt the file quote03 encrypted (using CAMELLIA256) with the key s!kR3T55 using gpg. What is the third word in the file?

understand

Task 3 Asymmetric Encryption

Bob has received the file ciphertext_message sent to him from Alice. You can find the key you need in the same folder. What is the first word of the original plaintext?

Perception

Take a look at Bob’s private RSA key. What is the last byte of p?

e7

fas fa-check-circle

Take a look at Bob’s private RSA key. What is the last byte of q?

27

Task 4 Diffie-Hellman Key Exchange

A set of Diffie-Hellman parameters can be found in the file dhparam.pem. What is the size of the prime number in bits?

4096

What is the prime number’s last byte (least significant byte)?

4f

Task 5 Hashing

What is the SHA256 checksum of the file order.json?

2c34b68669427d15f76a1c06ab941e3e6038dacdfb9209455c87519a3ef2c660

Open the file order.json and change the amount from 1000 to 9000. What is the new SHA256 checksum?

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Using SHA256 and the key 3RfDFz82, what is the HMAC of order.txt?

c7e4de386a09ef970300243a70a444ee2a4ca62413aeaeb7097d43d2c5fac89f

Task 6 PKI and SSL/TLS

What is the size of the public key in bits?

4096

Till which year is this certificate valid?

2039

Task 7 Authenticating with Passwords

What is the original password?

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that’s it ❤