ACSQL - Secretariat System

Overview

The ACSQL system is designed to manage university data related to students, courses, and their enrollments. It provides functionality to query, update, delete, and securely store the information using a simple encryption scheme.

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Data Structures

Secretariat

The core database structure containing:

• List of all students (studenti)
• List of all courses (materii)
• Enrollment details linking students to courses (inrolari)

Student

Fields:

• id - Unique student identifier
• nume - Full name of the student
• an_studiu - Year of study (1 to 4)
• statut - Type of study program ('b' for budget/state-funded, 't' for tax/self-funded)
• medie_generala - General average grade

Course (Materie)

Fields:

• id - Unique course ID
• nume - Course name
• nume_titular - Lead instructor's name

Enrollment (Înrolare)

Represents a many-to-many relationship between students and courses:

• id_student - Student ID
• id_materie - Course ID
• note - Grades array: [lab, midterm, final]

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Tasks

1. Database Management (10 points)

• 1.1 Load database from file: Function to read and load the database dynamically.
• 1.2 Add student: Add a new student to the database.
• 1.3 Free memory: Properly free allocated memory to prevent leaks.

2. Queries, Updates, Deletes (70 points)

• 2.1 Queries:

  • Simple queries (SELECT fields FROM table;)
  • Filtered queries (WHERE condition)
  • Complex filtered queries (two conditions joined by AND)

• 2.2 Updates & Deletes:

  • Update fields (except IDs) based on conditions.
  • Delete entries based on conditions.

3. Database Encryption (20 points)

• Implement a simplified Cipher Block Chaining (CBC) encryption on the students array before saving.
• Use a substitution-permutation network (SPN) with an S-box (XOR with key) and a P-box permutation.
• Split data into 4 equal-sized blocks, pad last block if necessary.
• XOR first block with IV, subsequent blocks XOR’d with previous ciphertext block.

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Encryption Example

Message: "Ana are mere!"
Key: pclp1
IV: ab

Steps:

1. Convert message to bytes.
2. Split into 4 blocks and pad last block.
3. XOR first block with IV repeated.
4. Apply S-box (XOR with key).
5. Apply P-box permutation.
6. Repeat for remaining blocks, chaining with previous ciphertext.

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Usage

• Compile and run the ACSQL system.
• Use the provided commands for querying, updating, deleting.
• Encryption protects sensitive student data on disk.

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Author

Your Name

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License

Specify your license here.