Secure Login System (Logic-Gate Password Verifier)

Overview

This project implements a highly obfuscated password verification system written in C++. Instead of performing a direct string comparison, the program converts user input into a bit-level representation and evaluates it through a large combinational logic circuit.

The system mimics a hardware-style verification process using boolean logic gates (AND, OR, NOT, etc.), making it intentionally difficult to reverse engineer or analyze through traditional static methods.

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How It Works

1. Input Handling

• The user is prompted to enter a password.
• The input string is converted into a fixed-size boolean array of 128 bits (PWDSIZEBITS).

2. ASCII to Bit Conversion

• Each character is converted into its 8-bit ASCII representation.
• These bits are stored sequentially in a boolean array.

3. Logic Circuit Evaluation

• The function runprogram1 simulates a large logic circuit.
• Each input bit is assigned to a variable (v0 through v127).
• A long chain of logic operations (primarily AND and NOT) evaluates whether the input matches a hidden condition.

4. Authentication Result

• If the final boolean output is true, access is granted.
• If false, access is denied.

5. Secret Output

• Upon successful authentication:
  • A hidden byte array (secret) is XORed with the input password.
  • The result is printed as the final output (likely a flag or decrypted message).

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Key Characteristics

• Bit-Level Verification
  Passwords are validated at the binary level rather than as strings.

• Obfuscation by Design
  The logic circuit is intentionally long and difficult to follow, making reverse engineering non-trivial.

• Deterministic Logic Chain
  The final result depends on a strict sequence of boolean conditions—all must evaluate to true.

• XOR-Based Secret Reveal
  The output is dynamically decrypted using the correct password.

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File Structure

• securelogin.cpp # Contains all logic, including input handling and verification

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Functions

convertAsciiToBool(char inputchar)

Converts a single character into an array of 8 boolean values representing its binary form.

convertString(char *str, bool inputAsBooleanVector[], int arraysize)

Converts a full string into a boolean bit vector.

runprogram1(bool input[], bool output[])

Core verification function that evaluates the input bits through a large boolean logic circuit.

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Compile

g++ -o secure_login securelogin.cpp

References

• SciTePress (2021). Conference Paper.
  https://www.scitepress.org/Papers/2021/105575/105575.pdf