+ File Decryption

lib.php

@@ -15,14 +15,23 @@ class kpcrypt {
     private $key = null;
 
     /**
-    * Define the number of blocks that should be read from the source file for each chunk.
-    * For 'AES-128-CBC' each block consist of 16 bytes.
-    * So if we read 10,000 blocks we load 160kb into memory. You may adjust this value
-    * to read/write shorter or longer chunks.
+     *  
+     * Define the number of blocks that should be read from the source file for each chunk.
+     * For 'AES-128-CBC' each block consist of 16 bytes.
+     * So if we read 10,000 blocks we load 160kb into memory. You may adjust this value
+     * to read/write shorter or longer chunks.
+     * 
+     * The higher this size is, the faster the file will be 
+     * processed but the more memory will in turn be also used
+     * 
     */
     private $blocks = 10000;
 
-    // A log of all of the errors, rather nice for debugging
+    /**
+     * A log of all of the errors, rather nice for debugging
+     * Please don't write to this, only read from it since
+     * it should only store errors about this class.
+     */
     private $errorLog = [];
 
     // The encryption cipher to use
@@ -148,6 +157,11 @@ class kpcrypt {
     // #endregion
 
 
+    /**
+     * File encryption should only be used on larger files ( 512kb+ )
+     * Since the string encryption will work better on the smaller files, since it's all
+     * in the memory, this simlpy pipes the file through itself, for every 1Mb file it only uses ~0.1Mb of memory with the default block size
+     */
     // #region File Encryption
 
         public function encryptFile(string $fileInput, string $fileOutput, bool $integrity_check = TRUE) {
@@ -193,8 +207,42 @@ class kpcrypt {
             return 1;
         }
 
+        /**
+         * @param string $fileInput The path to the encrypted file we want to decrypt
+         * @param string $fileOutput The path to where to place the decrypted content
+         */
         public function decryptFile(string $fileInput, string $fileOutput) {
 
+
+            // Try and open the destionation
+            if ( $fout = fopen($fileOutput, 'w') ) {
+                // Try and open the input file
+                if ($fin = fopen($fileInput, 'rb') ) {
+                    // Get the IV from the beginning of the file
+                    $iv = fread($fin, openssl_cipher_iv_length($this->cipherMethod));
+
+                    while (!feof($fin)) {
+                        // we have to read one block more for decrypting than for encrypting
+                        $ciphertext = fread($fin, 16 * ($this->blocks + 1));
+                        $plaintext = openssl_decrypt($ciphertext, $this->cipherMethod, $this->key, OPENSSL_RAW_DATA, $iv);
+                        // Use the first 16 bytes of the ciphertext as the next initialization vector
+                        $iv = substr($ciphertext, 0, 16);
+                        fwrite($fout, $plaintext);
+                    }
+
+                    // Close the input file
+                    fclose($fin);
+
+                } else {
+                    $this->errorLog[] = "[" . __LINE__ . "]" . "Could not open file output path for writing.";
+                    return false;
+                }
+    
+                // Close the output file
+                fclose($fout);
+                return 1;
+            }
+
         }
 
     // #endregion