Use an EVP base class to reduce repetition

1 files changed, 115 insertions, 0 deletions

diff --git a/src/crypt/cryptclassevp.cpp b/src/crypt/cryptclassevp.cpp
new file mode 100644
index 0000000..1ee09a0
--- /dev/null
+++ b/src/crypt/cryptclassevp.cpp
@@ -0,0 +1,115 @@
+#include "cryptclassevp.h"
+
+CryptClassEvp::CryptClassEvp()
+    : CryptClassBase()
+{
+    ERR_load_crypto_strings();
+    OpenSSL_add_all_algorithms();
+}
+
+CryptClassEvp::~CryptClassEvp()
+{
+    EVP_cleanup();
+    ERR_free_strings();
+}
+
+void CryptClassEvp::encrypt()
+{
+    m_cryptText = QByteArray(m_clearText.size(), 0);
+
+    EVP_CIPHER_CTX *ctx;
+
+    int len;
+
+    int ciphertext_len;
+
+    /* Create and initialise the context */
+    if (!(ctx = EVP_CIPHER_CTX_new()))
+    {
+        handleOpenSslError();
+    }
+
+    /* Initialise the encryption operation. IMPORTANT - ensure you use a key
+     * and IV size appropriate for your cipher */
+    if (1 != EVP_EncryptInit_ex(ctx, algorithm(), NULL, (unsigned char *) getKey().data(), (unsigned char *) getIV().data()))
+    {
+        handleOpenSslError();
+    }
+
+    /* 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()))
+    {
+        handleOpenSslError();
+    }
+
+    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))
+    {
+        handleOpenSslError();
+    }
+
+    ciphertext_len += len;
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+}
+
+void CryptClassEvp::decrypt()
+{
+    m_clearText = QByteArray(m_cryptText.size(), 0);
+
+    EVP_CIPHER_CTX *ctx;
+
+    int len;
+
+    int plaintext_len;
+
+    /* Create and initialise the context */
+    if (!(ctx = EVP_CIPHER_CTX_new()))
+    {
+        handleOpenSslError();
+    }
+
+    /* Initialise the decryption operation. IMPORTANT - ensure you use a key
+     * and IV size appropriate for your cipher */
+    if (1 != EVP_DecryptInit_ex(ctx, algorithm(), NULL, (unsigned char *) getKey().data(), (unsigned char *) getIV().data()))
+    {
+        handleOpenSslError();
+    }
+
+    /* Provide the message to be decrypted, and obtain the plaintext output.
+     * EVP_DecryptUpdate can be called multiple times if necessary
+     */
+    if (1 != EVP_DecryptUpdate(ctx, (unsigned char*) m_clearText.data(), &len, (unsigned char*) m_cryptText.data(), m_cryptText.length()))
+    {
+        handleOpenSslError();
+    }
+
+    plaintext_len = len;
+
+    /* Finalise the decryption. Further plaintext bytes may be written at
+     * this stage.
+     */
+    if (1 != EVP_DecryptFinal_ex(ctx, (unsigned char*) m_cryptText.data() + len, &len))
+    {
+        handleOpenSslError();
+    }
+
+    plaintext_len += len;
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+}
+
+void CryptClassEvp::handleOpenSslError()
+{
+    throw std::runtime_error(ERR_reason_error_string(ERR_get_error()));
+}