Banking System in C

A secure and user-friendly banking system implemented in C. This system allows users and administrators to perform various banking operations, such as checking account balances, setting transactions, and managing user/admin accounts. The system uses hash tables for efficient data storage and OpenSSL libraries for secure password hashing and salting.

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Features

User Features

• Login as User: Users can log in to access their accounts.
• Check Account Balance: View the current balance of the account.
• Check Personal Info: View personal information (name, surname, ID, etc.).
• Set Transaction: Send money to another user.
• See Transaction History: View a history of all transactions.
• Exit: Log out of the system.

Admin Features

• Login as Administrator: Admins can log in to manage the system.
• Insert a User: Add a new user to the system.
• Delete a User: Remove a user from the system.
• Lookup a User: Search for a specific user's details.
• List of all Users: Display all users in the system.
• Insert an Admin: Add a new admin to the system.
• Delete an Admin: Remove an admin from the system.
• Lookup an Admin: Search for a specific admin's details.
• List of all Admins: Display all admins in the system.
• Exit: Log out of the system.

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Technical Details

Data Structures

• Hash Tables: Used to store user and admin data for efficient lookup, insertion, and deletion.
  • User Hash Table: Stores person structures.
  • Admin Hash Table: Stores administrator structures.

Security

• Password Hashing: Passwords are hashed and salted using OpenSSL's SHA-256 and random salt generation.
• Secure Storage: Hashed passwords and salts are stored in CSV files (bankuser.csv and bankadmin.csv).

Error Handling

• The system gracefully handles incorrect inputs and other errors, providing clear error messages to the user.

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How It Works

Login Screen

When the program starts, the user is greeted with a login screen:

WELCOME (CTRL + C to force exit the program at any time)

Banking System
1. Login as user
2. Login as administrator
3. Exit
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User Menu

If the user selects 1. Login as user, they are presented with the following menu:

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User Menu
1. Check Account Balance
2. Check Personal Info
3. Set Transaction
4. See Transaction History
5. Exit
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Admin Menu

If the user selects 2. Login as administrator, they are presented with the following menu:

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Admin Menu
1. Insert a User
2. Delete a User
3. Lookup a User
4. List of all Users
5. Insert a Admin
6. Delete a Admin
7. Lookup a Admin
8. List of all Admins
9. Exit
________________________________________

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Exit

If the user selects 3. Exit, a goodbye message is displayed with their name.

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Installation and Usage

Prerequisites

• GCC: To compile the C code.
• OpenSSL: For password hashing and salting.

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Compilation

To compile the program, run the following command:

gcc -o bank bankingsyst_main.c bankingsyst_operations.c -I$(brew --prefix openssl)/include -L$(brew --prefix openssl)/lib -lssl -lcrypto

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Running the Program

After compilation, run the program using:

./bank

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File Structure

• bankingsyst_main.c: Contains the main program logic and menu handling.
• bankingsyst.h: Header file with structure definitions, function declarations, and constants.
• bankingsyst_operations.c: Contains the implementation of all functions (e.g., hash table operations, file I/O, password hashing).
• bankuser.csv: Stores user data (name, surname, ID, hashed password, salt, balance).
• bankadmin.csv: Stores admin data (name, surname, ID, hashed password, salt).
• transactions/: Directory containing transaction history files for each user (e.g., user123.csv).

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Error Handling

The system includes robust error handling to ensure smooth operation:

• Invalid inputs (e.g., non-numeric values, empty fields).
• Duplicate IDs during user/admin insertion.
• File I/O errors (e.g., missing or corrupted CSV files).
• Maximum login attempts (10 attempts before locking out).

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Security Considerations

• Password Hashing: Passwords are never stored in plaintext. They are hashed with a unique salt for each user/admin.
• File Permissions: Ensure that CSV files containing sensitive data have restricted permissions.
• Input Validation: All user inputs are validated to prevent buffer overflows or other vulnerabilities.

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Acknowledgments

• OpenSSL: For providing the libraries used for password hashing and salting.
• GCC: For the C compiler used to build this project.