#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 = 0;

    int ciphertext_len = 0;

    /* 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;

    m_cryptText.resize(ciphertext_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;
    m_clearText.resize(plaintext_len);
    /* Clean up */
    EVP_CIPHER_CTX_free(ctx);
}

void CryptClassEvp::handleOpenSslError()
{
    throw std::runtime_error(ERR_reason_error_string(ERR_get_error()));
}