Implemented digestion (feeding one block at a time)

GCryptLib/src/Cipher.cpp

@@ -6,18 +6,22 @@
 
 namespace Leonetienne::GCrypt {
 
-  Cipher::Cipher(const Block& key)
+  Cipher::Cipher(const Block& key, const CIPHER_DIRECTION direction)
     :
     key { key },
-    initializationVector(InitializationVector(key)) {
+    direction { direction },
+    lastBlock(InitializationVector(key)), // Initialize our lastBlock with some deterministic initial value, based on the key
+    feistel(key) {
 
     return;
   }
 
-  Cipher::Cipher(const std::string& password)
+  Cipher::Cipher(const std::string& password, const CIPHER_DIRECTION direction)
     :
     key { PasswordToKey(password) },
-    initializationVector(InitializationVector(key)) {
+    direction { direction },
+    lastBlock(InitializationVector(key)),  // Initialize our lastBlock with some deterministic initial value, based on the key   feistel(key) {
+    feistel(key) {
     return;
   }
 
@@ -28,20 +32,42 @@ namespace Leonetienne::GCrypt {
     return;
   }
 
-  void Cipher::SetKey(const Block& key) {
-    ZeroKeyMemory();
+  Block Cipher::Digest(const Block& input) {
+
+    switch (direction) {
+      case CIPHER_DIRECTION::ENCIPHER: {
+        // Rename our input to cleartext
+        const Block& cleartext = input;
+
+        // First, xor our cleartext with the last block, and then encipher it
+        Block ciphertext = feistel.Encipher(cleartext ^ lastBlock);
+
+        // Now set our lastBlock to the ciphertext of this block
+        lastBlock = ciphertext;
+
+        // Now return the ciphertext
+        return ciphertext;
+      }
+
+      case CIPHER_DIRECTION::DECIPHER: {
+        // Rename our input into ciphertext
+        const Block& ciphertext = input;
+
+        // First, decipher our ciphertext, and then xor it with our last block
+        Block cleartext = feistel.Decipher(ciphertext) ^ lastBlock;
+
+        // Now set our lastBLock to the ciphertext of this block
+        lastBlock = ciphertext;
+
+        // Now return the cleartext
+        return cleartext;
+      }
+    }
+
 
-    this->key = key;
-    return;
-  }
-
-  void Cipher::SetPassword(const std::string& password) {
-    ZeroKeyMemory();
-
-    key = PasswordToKey(password);
-    return;
   }
 
+  /*
   Flexblock Cipher::Encipher(const Flexblock& data, bool printProgress) const {
     // Split cleartext into blocks
     std::vector<Block> blocks;
@@ -113,6 +139,7 @@ namespace Leonetienne::GCrypt {
     // Return it
     return ss.str();
   }
+*/
 
   // These pragmas only work for MSVC and g++, as far as i know. Beware!!!
 #if defined _WIN32 || defined _WIN64

GCryptLib/src/GCryptWrapper.cpp

@@ -5,15 +5,14 @@
 namespace Leonetienne::GCrypt {
 
   std::string GCryptWrapper::EncryptString(const std::string& cleartext, const std::string& password) {
-    // Instanciate our cipher and supply a key
+    // Transform the password to a key
     const Block key = PasswordToKey(password);
-    Cipher cipher(key);
 
     // Recode the ascii-string to bits
     const Flexblock cleartext_bits = StringToBits(cleartext);
 
     // Encrypt our cleartext bits
-    const Flexblock ciphertext_bits = cipher.Encipher(cleartext_bits);
+    const Flexblock ciphertext_bits = DigestFlexblock(cleartext_bits, key, Cipher::CIPHER_DIRECTION::ENCIPHER);
 
     // Recode the ciphertext bits to a hex-string
     const std::string ciphertext = BitsToHexstring(ciphertext_bits);
@@ -23,15 +22,14 @@ namespace Leonetienne::GCrypt {
   }
 
   std::string GCryptWrapper::DecryptString(const std::string& ciphertext, const std::string& password) {
-    // Instanciate our cipher and supply a key
+    // Transform the password to a key
     const Block key = PasswordToKey(password);
-    Cipher cipher(key);
 
     // Recode the hex-string to bits
     const Flexblock ciphertext_bits = HexstringToBits(ciphertext);
 
     // Decrypt the ciphertext bits
-    const std::string cleartext_bits = cipher.Decipher(ciphertext_bits);
+    const std::string cleartext_bits = DigestFlexblock(ciphertext_bits, key, Cipher::CIPHER_DIRECTION::DECIPHER);
 
     // Recode the cleartext bits to an ascii-string
     const std::string cleartext = BitsToString(cleartext_bits);
@@ -45,12 +43,11 @@ namespace Leonetienne::GCrypt {
       // Read the file to bits
       const Flexblock cleartext_bits = ReadFileToBits(filename_in);
 
-      // Instanciate our cipher and supply a key
+      // Transform the password to a key
       const Block key = PasswordToKey(password);
-      Cipher cipher(key);
 
       // Encrypt our cleartext bits
-      const Flexblock ciphertext_bits = cipher.Encipher(cleartext_bits, printProgressReport);
+      const Flexblock ciphertext_bits = DigestFlexblock(cleartext_bits, key, Cipher::CIPHER_DIRECTION::ENCIPHER);
 
       // Write our ciphertext bits to file
       WriteBitsToFile(filename_out, ciphertext_bits);
@@ -67,12 +64,11 @@ namespace Leonetienne::GCrypt {
       // Read the file to bits
       const Flexblock ciphertext_bits = ReadFileToBits(filename_in);
 
-      // Instanciate our cipher and supply a key
+      // Transform the password to a key
       const Block key = PasswordToKey(password);
-      Cipher cipher(key);
 
       // Decrypt the ciphertext bits
-      const Flexblock cleartext_bits = cipher.Decipher(ciphertext_bits, printProgressReport);
+      const Flexblock cleartext_bits = DigestFlexblock(ciphertext_bits, key, Cipher::CIPHER_DIRECTION::DECIPHER);
 
       // Write our cleartext bits to file
       WriteBitsToFile(filename_out, cleartext_bits);
@@ -84,5 +80,32 @@ namespace Leonetienne::GCrypt {
     }
   }
 
+  Flexblock GCryptWrapper::DigestFlexblock(const Flexblock& data, const Block& key, const Cipher::CIPHER_DIRECTION direction) {
+    // Split input into blocks
+    std::vector<Block> blocks;
+
+    for (std::size_t i = 0; i < data.size(); i += BLOCK_SIZE) {
+      blocks.push_back(Block(
+        PadStringToLength(data.substr(i, BLOCK_SIZE), BLOCK_SIZE, '0', false))
+      );
+    }
+
+    // Create cipher instance
+    Cipher cipher(key, direction);
+
+    // Digest all blocks
+    for (Block& block : blocks) {
+      block = cipher.Digest(block);
+    }
+
+    // Concatenate ciphertext blocks back into a flexblock
+    std::stringstream ss;
+    for (Block& b : blocks) {
+      ss << b;
+    }
+
+    // Return it
+    return ss.str();
+  }
 }