Merge pull request #5 from sanghaibiraj/main

feat: password generator

Author: prajwal3114

Src/Password_Generator/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.15)
+project(Password_Generator LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+add_library(pwg
+    src/Random.cpp
+    src/PasswordGenerator.cpp
+    src/PasswordStrengthEvaluator.cpp
+)
+
+target_include_directories(pwg PUBLIC include)
+
+add_executable(password_generator
+    src/main.cpp
+)
+
+target_link_libraries(password_generator PRIVATE pwg)

Src/Password_Generator/README.md

@@ -32,3 +32,61 @@ The project is designed to be **modular, maintainable, and easy to extend**, fol
 1. Clone the repository:  
    ```bash
    git clone https://github.com/your-username/your-repo.git
+   ```
+2. Navigate to the Password Generator project directory:
+   ```bash
+   cd your-repo/Src/Password_Generator
+   ```
+3. Build with CMake:
+   ```bash
+   mkdir -p build && cd build
+   cmake ..
+   cmake --build .
+   ```
+4. Run:
+   ```bash
+   ./password_generator
+   ```
+
+Alternative: build without CMake (ensure you are in Src/Password_Generator)
+```bash
+g++ -std=cpp17 -Iinclude src/*.cpp -o password_generator
+./password_generator
+```
+
+## Usage
+The app runs in interactive CLI mode.
+
+- Option 1 (Preset): Choose weak, medium, or strong, then how many passwords to generate.
+- Option 2 (Custom): Choose length, inclusion of lowercase/uppercase/digits/symbols, whether to require at least one of each selected type, and how many passwords.
+
+Example session
+```
+C++ Password Generator
+1) Preset (weak/medium/strong)
+2) Custom
+Choose option [1/2]: 1
+Preset [weak/medium/strong]: strong
+How many passwords to generate [1]: 3
+[1] 2Gz!tq@K3wqM)h^L  (entropy: 95 bits, strength: strong)
+[2] Lz5{nZV8pQ%g=J7!  (entropy: 95 bits, strength: strong)
+[3] 7Y@kR`mT2s&Qh9)C  (entropy: 95 bits, strength: strong)
+```
+
+Options explained
+- length: number of characters in each password.
+- includeLowercase/includeUppercase/includeDigits/includeSymbols: toggle character sets.
+- requireEachSelectedType: if enabled, guarantees at least one character from each selected set and shuffles the result.
+- count: how many passwords to output.
+
+## Design overview (OOP + SOLID)
+- PasswordGenerator: single responsibility to generate passwords; depends on abstractions.
+- IRandom + MTRandom: randomness abstraction and mt19937-based implementation (Dependency Inversion).
+- UserPreferences: clean container for user options and presets (Weak/Medium/Strong).
+- IPasswordStrengthEvaluator + EntropyPasswordStrengthEvaluator: pluggable strength evaluation.
+- CharacterSets: centralized immutable character sets.
+- Dependency Injection: Generator receives IRandom; evaluator is independent and reusable.
+
+## Notes
+- Requires a C++17-compatible compiler and CMake 3.15+ (if using CMake).
+- Input validated with helpful error messages (e.g., length must be > 0, at least one character set required).

Src/Password_Generator/include/CharacterSets.h

@@ -0,0 +1,7 @@
+#pragma once
+namespace charset {
+    inline constexpr const char* LOWER  = "abcdefghijklmnopqrstuvwxyz";
+    inline constexpr const char* UPPER  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    inline constexpr const char* DIGITS = "0123456789";
+    inline constexpr const char* SYMBOLS= "!@#$%^&*()-_=+[]{}|;:,.<>?/~`";
+}

Src/Password_Generator/include/IPasswordStrengthEvaluator.h

@@ -0,0 +1,11 @@
+#pragma once
+#include <string>
+
+enum class PasswordStrength { Weak, Medium, Strong };
+
+struct IPasswordStrengthEvaluator {
+    virtual ~IPasswordStrengthEvaluator() = default;
+    virtual double entropyBits(const std::string& password) const = 0;
+    virtual PasswordStrength classify(double entropyBits) const = 0;
+    virtual const char* toString(PasswordStrength s) const = 0;
+};

Src/Password_Generator/include/IRandom.h

@@ -0,0 +1,7 @@
+#pragma once
+#include <cstddef>
+
+struct IRandom {
+    virtual ~IRandom() = default;
+    virtual std::size_t nextIndex(std::size_t upperExclusive) = 0; // [0, upperExclusive)
+};

Src/Password_Generator/include/PasswordGenerator.h

@@ -0,0 +1,22 @@
+#pragma once
+#include "IRandom.h"
+#include "UserPreferences.h"
+#include <string>
+#include <vector>
+
+class PasswordGenerator {
+public:
+    explicit PasswordGenerator(IRandom& rng);
+
+    std::string generate(const UserPreferences& prefs);
+    std::vector<std::string> generateMany(const UserPreferences& prefs);
+
+private:
+    IRandom& rng_;
+
+    std::string buildAlphabet(const UserPreferences& prefs) const;
+    void ensureValid(const UserPreferences& prefs) const;
+    char randomFrom(const std::string& alphabet);
+    void fisherYatesShuffle(std::string& s);
+    std::string generateWithEachType(const UserPreferences& prefs, const std::string& alphabet);
+};

Src/Password_Generator/include/PasswordStrengthEvaluator.h

@@ -0,0 +1,9 @@
+#pragma once
+#include "IPasswordStrengthEvaluator.h"
+
+class EntropyPasswordStrengthEvaluator final : public IPasswordStrengthEvaluator {
+public:
+    double entropyBits(const std::string& password) const override;
+    PasswordStrength classify(double entropyBits) const override;
+    const char* toString(PasswordStrength s) const override;
+};

Src/Password_Generator/include/Random.h

@@ -0,0 +1,12 @@
+#pragma once
+#include "IRandom.h"
+#include <random>
+
+class MTRandom final : public IRandom {
+public:
+    explicit MTRandom(unsigned int seed = std::random_device{}());
+    std::size_t nextIndex(std::size_t upperExclusive) override;
+
+private:
+    std::mt19937 engine_;
+};

Src/Password_Generator/include/UserPreferences.h

@@ -0,0 +1,22 @@
+#pragma once
+#include <cstddef>
+
+struct UserPreferences {
+    std::size_t length{12};
+    bool includeLowercase{true};
+    bool includeUppercase{true};
+    bool includeDigits{true};
+    bool includeSymbols{false};
+    std::size_t count{1};
+    bool requireEachSelectedType{true};
+
+    static UserPreferences Weak() {
+        return UserPreferences{8, true, false, false, false, 1, false};
+    }
+    static UserPreferences Medium() {
+        return UserPreferences{12, true, true, true, false, 1, true};
+    }
+    static UserPreferences Strong() {
+        return UserPreferences{16, true, true, true, true, 1, true};
+    }
+};

Src/Password_Generator/src/PasswordGenerator.cpp

@@ -0,0 +1,80 @@
+#include "PasswordGenerator.h"
+#include "CharacterSets.h"
+#include <stdexcept>
+
+PasswordGenerator::PasswordGenerator(IRandom& rng) : rng_{rng} {}
+
+void PasswordGenerator::ensureValid(const UserPreferences& prefs) const {
+    if (prefs.length == 0) throw std::invalid_argument("Password length must be > 0");
+    if (!prefs.includeLowercase && !prefs.includeUppercase && !prefs.includeDigits && !prefs.includeSymbols) {
+        throw std::invalid_argument("At least one character set must be enabled");
+    }
+    std::size_t types = (prefs.includeLowercase?1:0) + (prefs.includeUppercase?1:0) +
+                        (prefs.includeDigits?1:0) + (prefs.includeSymbols?1:0);
+    if (prefs.requireEachSelectedType && prefs.length < types) {
+        throw std::invalid_argument("Length too short to include at least one of each selected type");
+    }
+}
+
+std::string PasswordGenerator::buildAlphabet(const UserPreferences& prefs) const {
+    std::string alphabet;
+    if (prefs.includeLowercase) alphabet += charset::LOWER;
+    if (prefs.includeUppercase) alphabet += charset::UPPER;
+    if (prefs.includeDigits)    alphabet += charset::DIGITS;
+    if (prefs.includeSymbols)   alphabet += charset::SYMBOLS;
+    return alphabet;
+}
+
+char PasswordGenerator::randomFrom(const std::string& alphabet) {
+    return alphabet[rng_.nextIndex(alphabet.size())];
+}
+
+void PasswordGenerator::fisherYatesShuffle(std::string& s) {
+    if (s.size() <= 1) return;
+    for (std::size_t i = s.size() - 1; i > 0; --i) {
+        std::size_t j = rng_.nextIndex(i + 1);
+        std::swap(s[i], s[j]);
+    }
+}
+
+std::string PasswordGenerator::generateWithEachType(const UserPreferences& prefs, const std::string& alphabet) {
+    std::string pw;
+    pw.reserve(prefs.length);
+
+    // Ensure at least one char from each selected set
+    if (prefs.includeLowercase) pw.push_back(randomFrom(charset::LOWER));
+    if (prefs.includeUppercase) pw.push_back(randomFrom(charset::UPPER));
+    if (prefs.includeDigits)    pw.push_back(randomFrom(charset::DIGITS));
+    if (prefs.includeSymbols)   pw.push_back(randomFrom(charset::SYMBOLS));
+
+    // Fill remaining with random chars from the combined alphabet
+    while (pw.size() < prefs.length) {
+        pw.push_back(randomFrom(alphabet));
+    }
+
+    fisherYatesShuffle(pw);
+    return pw;
+}
+
+std::string PasswordGenerator::generate(const UserPreferences& prefs) {
+    ensureValid(prefs);
+    const std::string alphabet = buildAlphabet(prefs);
+    if (prefs.requireEachSelectedType) return generateWithEachType(prefs, alphabet);
+
+    std::string pw;
+    pw.reserve(prefs.length);
+    for (std::size_t i = 0; i < prefs.length; ++i) {
+        pw.push_back(randomFrom(alphabet));
+    }
+    return pw;
+}
+
+std::vector<std::string> PasswordGenerator::generateMany(const UserPreferences& prefs) {
+    if (prefs.count == 0) throw std::invalid_argument("Count must be > 0");
+    std::vector<std::string> out;
+    out.reserve(prefs.count);
+    for (std::size_t i = 0; i < prefs.count; ++i) {
+        out.push_back(generate(prefs));
+    }
+    return out;
+}