Fix Blowfish and Blowfish2 correctness issues and improve initialization safety

In Blowfish
- Fix incorrect F-function byte extraction (critical bug).
- Correct key-schedule handling by using `uint8_t` key bytes.
- Initialize local variables in `initialize()` to prevent UB.
- Improve decrypt loop and XOR usage for clarity and correctness.

In Blowfish2
- Zero-initialize P-array and S-boxes to guarantee deterministic state.
- Fix incorrect key size comment (448 bits, not 4224 bits).
- Improve F-function byte extraction clarity.
- Normalize round loop logic and use XOR-assignment.

Others
- Replace macro `N` with `constexpr N`.
- Add `noexcept` to internal operations.
- Add `initialize(const uint8_t*, size_t)` overload for binary keys.
- Clean up readability and internal consistency across both ciphers.

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

include/blowfish/blowfish.h

@@ -4,32 +4,34 @@
 // Original Blowfish Algorithm copyright:
 // SPDX-FileCopyrightText: 1997 Paul Kocher
 
-#include <algorithm>
+#pragma once
 #include <array>
 #include <cstdint>
 #include <string>
 
 #define MAXKEYBYTES 56 // 448 bits max
-#define N 16
+static constexpr uint32_t N = 16;
 
 #if !defined(BLOWFISH_BLOWFISH_H_)
 #define BLOWFISH_BLOWFISH_H_
 
 class Blowfish {
 private:
-  std::array<uint32_t, N + 2> PArray;
-  std::array<std::array<uint32_t, 256>, 4> Sboxes;
-  uint32_t F(uint32_t x);
+  std::array<uint32_t, N + 2> PArray{};
+  std::array<std::array<uint32_t, 256>, 4> Sboxes{};
+  uint32_t F(uint32_t x) const noexcept;
 
 public:
-  Blowfish() {}
-  Blowfish(std::string const &key);
+  Blowfish() = default;
+  explicit Blowfish(std::string const &key);
   Blowfish(Blowfish const &) = delete;
 
-  void initialize(std::string const &key);
+  void initialize(const uint8_t *key, size_t keylen);
+  void initialize(const std::string &key);
 
-  void encrypt(uint32_t &xl, uint32_t &xr);
-  void decrypt(uint32_t &xl, uint32_t &xr);
+  void encrypt(uint32_t &xl, uint32_t &xr) noexcept;
+  void decrypt(uint32_t &xl, uint32_t &xr) noexcept;
+  ~Blowfish();
 };
 
 #endif // BLOWFISH_BLOWFISH_H_

include/blowfish/blowfish2.h

@@ -4,32 +4,35 @@
 // Original Blowfish 2 Algorithm copyright:
 // SPDX-FileCopyrightText: 2005 Alexander Pukall
 
-#include <algorithm>
+#pragma once
 #include <array>
 #include <cstdint>
 #include <string>
 
-#define MAXKEYBYTES 56 // 4224 bits max
-#define N 64
+#define MAXKEYBYTES 56 // 448 bits max
 
 #if !defined(BLOWFISH_BLOWFISH2_H_)
 #define BLOWFISH_BLOWFISH2_H_
 
 class Blowfish2 {
 private:
-  std::array<uint64_t, N + 2> PArray;
-  std::array<std::array<uint64_t, 256>, 8> Sboxes;
-  uint64_t F(uint64_t x);
+  static constexpr uint64_t N = 64;
+  std::array<uint64_t, N + 2> PArray{};
+  std::array<std::array<uint64_t, 256>, 8> Sboxes{};
+  uint64_t F(uint64_t x) const noexcept;
 
 public:
-  Blowfish2() {}
-  Blowfish2(std::string const &key);
-  Blowfish2(Blowfish2 const &) = delete;
+  Blowfish2() = default;
+  explicit Blowfish2(const std::string &key) { initialize(key); }
+
+  Blowfish2(const Blowfish2 &) = delete;
+  Blowfish2 &operator=(const Blowfish2 &) = delete;
 
   void initialize(std::string const &key);
+  void initialize(const uint8_t *key, size_t keylen);
 
-  void encrypt(uint64_t &xl, uint64_t &xr);
-  void decrypt(uint64_t &xl, uint64_t &xr);
+  void encrypt(uint64_t &xl, uint64_t &xr) noexcept;
+  void decrypt(uint64_t &xl, uint64_t &xr) noexcept;
 };
 
 #endif // BLOWFISH_BLOWFISH2_H_