From 8f5835824c4be7e72195d6c3fce18d85c079c31e Mon Sep 17 00:00:00 2001
From: Stefan Suhren <suhren.stefan@fh-swf.de>
Date: Tue, 19 May 2015 13:13:20 +0200
Subject: First try of using the EVP null chipher from OpenSSL

---
 src/crypt/cryptclassnullcipher.cpp | 67 +++++++++++++++++++++++++++++++++++++-
 src/crypt/cryptclassnullcipher.h   | 15 ++++++++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/src/crypt/cryptclassnullcipher.cpp b/src/crypt/cryptclassnullcipher.cpp
index b4ed284..c30b2e2 100644
--- a/src/crypt/cryptclassnullcipher.cpp
+++ b/src/crypt/cryptclassnullcipher.cpp
@@ -3,15 +3,80 @@
 CryptClassNullCipher::CryptClassNullCipher()
     : CryptClassBase()
 {
+    ERR_load_crypto_strings();
+    OpenSSL_add_all_algorithms();
+}
 
+CryptClassNullCipher::~CryptClassNullCipher()
+{
+    EVP_cleanup();
+    ERR_free_strings();
 }
 
 void CryptClassNullCipher::encrypt()
 {
-    m_cryptText = m_clearText;
+    //    int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key,
+    //             unsigned char *iv, unsigned char *ciphertext)
+
+    m_cryptText = QByteArray(m_clearText.size() + 50, 0);
+
+    EVP_CIPHER_CTX *ctx;
+
+    int len;
+
+    int ciphertext_len;
+
+    /* Create and initialise the context */
+    if (!(ctx = EVP_CIPHER_CTX_new()))
+    {
+        qDebug() << "EVP_CIPHER_CTX_new";
+        handleErrors();
+    }
+
+    /* Initialise the encryption operation. IMPORTANT - ensure you use a key
+     * and IV size appropriate for your cipher
+     * In this example we are using 256 bit AES (i.e. a 256 bit key). The
+     * IV size for *most* modes is the same as the block size. For AES this
+     * is 128 bits */
+    if (1 != EVP_EncryptInit_ex(ctx, EVP_enc_null(), NULL, NULL, NULL))
+    {
+        qDebug() << "EVP_EncryptInit_ex";
+        handleErrors();
+    }
+
+    /* Provide the message to be encrypted, and obtain the encrypted output.
+     * EVP_EncryptUpdate can be called multiple times if necessary
+     */
+    if (1 != EVP_EncryptUpdate(ctx, (unsigned char *) m_cryptText.data(), &len, (unsigned char *) m_clearText.data(), m_clearText.length()))
+    {
+        qDebug() << "EVP_EncryptUpdate";
+        handleErrors();
+    }
+
+    ciphertext_len = len;
+
+    /* Finalise the encryption. Further ciphertext bytes may be written at
+     * this stage.
+     */
+    if (1 != EVP_EncryptFinal_ex(ctx, (unsigned char *) (m_cryptText.data() + len), &len))
+    {
+        qDebug() << "EVP_EncryptFinal_ex";
+        handleErrors();
+    }
+
+    ciphertext_len += len;
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
 }
 
 void CryptClassNullCipher::decrypt()
 {
     m_clearText = m_cryptText;
 }
+
+void CryptClassNullCipher::handleErrors()
+{
+    qDebug() << ERR_get_error();
+    abort();
+}
diff --git a/src/crypt/cryptclassnullcipher.h b/src/crypt/cryptclassnullcipher.h
index 6b3c284..ae05ef6 100644
--- a/src/crypt/cryptclassnullcipher.h
+++ b/src/crypt/cryptclassnullcipher.h
@@ -3,7 +3,11 @@
 
 #include "cryptclassbase.h"
 
+#include <QDebug>
+
 #include <openssl/evp.h>
+#include <openssl/err.h>
+#include <openssl/conf.h>
 
 
 /**
@@ -23,10 +27,16 @@ public: //Methods
     /**
     * \brief Class Constructor.
     *
-    * Class Constructor. Does nothing.
+    * Class Constructor. Initializes openssl.
     */
     CryptClassNullCipher();
 
+    /**
+     * \brief Class Destructor.
+     *
+     * Class Destructor. Deinitializes openssl.
+     */
+    ~CryptClassNullCipher();
 
     /**
     * \brief Overloaded Method to encrypt present unencrypted data using the current key.
@@ -44,6 +54,9 @@ public: //Methods
     * Data is copied from m_cryptText to m_clearText.
     */
     virtual void decrypt();
+
+private:
+    void handleErrors();
 };
 
 #endif // CRYPTCLASSNULLCIPHER_H
-- 
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