Cryptography || Tugas Akhir Praktikum Keamanan Sistem Informasi || Arbian Alex Pritama

Summary

In this educational video, the presenter introduces the concepts of cryptography, detailing both classical and modern methods. Classical techniques like Caesar and Vigenère ciphers are briefly mentioned, while modern cryptography is split into symmetric (RC4, DES) and asymmetric (RSA, DSA) types. The tutorial focuses on a practical demonstration, guiding viewers through the installation of Apache and setting up a PHP script for encryption and decryption. The script includes form handling, text processing, and saving encrypted data to a file, showcasing the encryption and decryption process in action.

Takeaways

• 🔐 The video introduces the concept of cryptography, which is the study and practice of securing messages.
• 🔑 It distinguishes between two types of cryptography: classical and modern cryptography.
• 📜 Classical cryptography includes methods like Caesar cipher, transposition cipher, and others.
• 💡 Modern cryptography is divided into symmetric and asymmetric cryptography, with algorithms such as RC4, DES, AES, IDEA for symmetric, and RSA, DSA, and ECC for asymmetric.
• 🛠️ The video demonstrates the installation and setup of a cryptographic tool, likely a web-based application, by installing packages and restarting services.
• 🌐 It provides a walkthrough of accessing the tool's interface through a web browser by navigating to a specific IP address.
• 📝 The script explains the process of encryption using a form in 'awal.php', which takes user input and processes it through 'nkiser.php'.
• 🔢 It details the encryption process, which involves converting text to decimal, performing encryption, and then converting the result back to ASCII.
• 📝 The encrypted text is then saved to a file named 'enkripsi.txt', which is accessible and modifiable with specific permissions.
• 🔄 The video also covers the decryption process in 'akhir.php', which involves reading the encrypted file, decrypting it, and displaying the original message.
• 🔒 The importance of matching encryption and decryption keys ('q' value) is emphasized for successful decryption.

Q & A

What is cryptography?

Cryptography is the science and art of securing messages.

What are the two types of cryptography mentioned in the script?

The two types of cryptography mentioned are classical cryptography and modern cryptography.

Can you name some examples of classical cryptography techniques?

Examples of classical cryptography techniques include Caesar cipher, fine cipher, and Vigenère cipher.

What is the difference between symmetric and asymmetric cryptography?

In symmetric cryptography, the same key is used for both encryption and decryption, while in asymmetric cryptography, two different keys are used – a public key for encryption and a private key for decryption.

Which algorithms are mentioned in the script for symmetric cryptography?

The script mentions RC4 and DES as examples of symmetric cryptography algorithms.

What does the script say about the installation process of a package?

The script describes installing a package using 'apt-get install' and then restarting the service with 'service apache2 restart'.

How does the script explain the encryption process in the 'awal.php' file?

The 'awal.php' file contains a form for encryption, which takes user input and processes it through a series of steps including converting text to decimal, encrypting it, and then converting it back to ASCII.

What is the purpose of the 'enkripsi.txt' file mentioned in the script?

The 'enkripsi.txt' file is used to store the encrypted output of the encryption process.

How does the script describe the decryption process in the 'akhir.php' file?

The 'akhir.php' file is responsible for decryption, where it retrieves the key from 'enkripsi.txt', reads the encrypted data, and performs the decryption process by reversing the steps used in encryption.

What is the significance of the 'q' value in the encryption and decryption process as described in the script?

The 'q' value is significant as it is used in the encryption and decryption process to modify the text. It must be the same in both processes to ensure the original message can be correctly decrypted.

How does the script guide users to view the results of the encryption and decryption processes?

The script guides users to view the results by accessing the 'awal.php' and 'akhir.php' files through a web browser and entering the necessary inputs to see the original and encrypted/decrypted messages.