Function get_crypt_context

libcppcryptfs/crypt/crypt.cpp:55–92

}

shared_ptr<EVP_CIPHER_CTX> get_crypt_context(int ivlen, int mode)
{
	EVP_CIPHER_CTX*ctx = NULL;

	try {
		/* Create and initialise the context */
		if (!(ctx = EVP_CIPHER_CTX_new())) handleErrors();

		const EVP_CIPHER *cipher = NULL;

		switch (mode) {
	
		case AES_MODE_GCM:
			cipher = EVP_aes_256_gcm();
			break;
		default:
			handleErrors();
			break;
		}

		/* Initialise the encryption operation. */
		if (1 != EVP_EncryptInit_ex(ctx, cipher, NULL, NULL, NULL))
			handleErrors();

		if (mode == AES_MODE_GCM && ivlen != 12) {
			/* Set IV length. Not necessary if this is 12 bytes (96 bits) */
			if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, ivlen, NULL))
				handleErrors();
		}

	} catch (int) {
		if (ctx)
			EVP_CIPHER_CTX_free(ctx);
		ctx = nullptr;
	}

	return shared_ptr<EVP_CIPHER_CTX>(ctx, free_crypt_context);
}

int encrypt(const unsigned char *plaintext, int plaintext_len, unsigned char *aad,
	int aad_len, const unsigned char *key, const unsigned char *iv,