chapoly: Provide a generic ChaCha20/Poly1305 AEAD supporting driver backends

configure.ac

@@ -127,6 +127,7 @@ ARG_ENABL_SET([af-alg],         [enable AF_ALG crypto interface to Linux Crypto
 ARG_ENABL_SET([bliss],          [enable BLISS software implementation plugin.])
 ARG_ENABL_SET([blowfish],       [enable Blowfish software implementation plugin.])
 ARG_ENABL_SET([ccm],            [enables the CCM AEAD wrapper crypto plugin.])
+ARG_ENABL_SET([chapoly],        [enables the ChaCha20/Poly1305 AEAD plugin.])
 ARG_DISBL_SET([cmac],           [disable CMAC crypto implementation plugin.])
 ARG_ENABL_SET([ctr],            [enables the Counter Mode wrapper crypto plugin.])
 ARG_DISBL_SET([des],            [disable DES/3DES software implementation plugin.])
@@ -1293,6 +1294,7 @@ ADD_PLUGIN([fips-prf],             [s charon nm cmd])
 ADD_PLUGIN([gmp],                  [s charon scepclient pki scripts manager medsrv attest nm cmd aikgen])
 ADD_PLUGIN([agent],                [s charon nm cmd])
 ADD_PLUGIN([keychain],             [s charon cmd])
+ADD_PLUGIN([chapoly],              [s charon scripts nm cmd])
 ADD_PLUGIN([xcbc],                 [s charon nm cmd])
 ADD_PLUGIN([cmac],                 [s charon nm cmd])
 ADD_PLUGIN([hmac],                 [s charon pki scripts nm cmd])
@@ -1449,6 +1451,7 @@ AM_CONDITIONAL(USE_GCRYPT, test x$gcrypt = xtrue)
 AM_CONDITIONAL(USE_AGENT, test x$agent = xtrue)
 AM_CONDITIONAL(USE_KEYCHAIN, test x$keychain = xtrue)
 AM_CONDITIONAL(USE_PKCS11, test x$pkcs11 = xtrue)
+AM_CONDITIONAL(USE_CHAPOLY, test x$chapoly = xtrue)
 AM_CONDITIONAL(USE_CTR, test x$ctr = xtrue)
 AM_CONDITIONAL(USE_CCM, test x$ccm = xtrue)
 AM_CONDITIONAL(USE_GCM, test x$gcm = xtrue)
@@ -1698,6 +1701,7 @@ AC_CONFIG_FILES([
 	src/libstrongswan/plugins/agent/Makefile
 	src/libstrongswan/plugins/keychain/Makefile
 	src/libstrongswan/plugins/pkcs11/Makefile
+	src/libstrongswan/plugins/chapoly/Makefile
 	src/libstrongswan/plugins/ctr/Makefile
 	src/libstrongswan/plugins/ccm/Makefile
 	src/libstrongswan/plugins/gcm/Makefile

src/libstrongswan/Makefile.am

@@ -540,6 +540,13 @@ if MONOLITHIC
 endif
 endif
 
+if USE_CHAPOLY
+  SUBDIRS += plugins/chapoly
+if MONOLITHIC
+  libstrongswan_la_LIBADD += plugins/chapoly/libstrongswan-chapoly.la
+endif
+endif
+
 if USE_CTR
   SUBDIRS += plugins/ctr
 if MONOLITHIC

src/libstrongswan/plugins/chapoly/Makefile.am

@@ -0,0 +1,18 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src/libstrongswan
+
+AM_CFLAGS = \
+	$(PLUGIN_CFLAGS)
+
+if MONOLITHIC
+noinst_LTLIBRARIES = libstrongswan-chapoly.la
+else
+plugin_LTLIBRARIES = libstrongswan-chapoly.la
+endif
+
+libstrongswan_chapoly_la_SOURCES = \
+	chapoly_plugin.h chapoly_plugin.c \
+	chapoly_drv.h chapoly_drv.c \
+	chapoly_aead.h chapoly_aead.c
+
+libstrongswan_chapoly_la_LDFLAGS = -module -avoid-version

src/libstrongswan/plugins/chapoly/chapoly_aead.c

@@ -0,0 +1,333 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "chapoly_aead.h"
+#include "chapoly_drv.h"
+
+#include <crypto/iv/iv_gen_seq.h>
+
+/* maximum plain message size */
+#define P_MAX 247877906880
+
+typedef struct private_chapoly_aead_t private_chapoly_aead_t;
+
+/**
+ * Private data of an chapoly_aead_t object.
+ */
+struct private_chapoly_aead_t {
+
+	/**
+	 * Public chapoly_aead_t interface.
+	 */
+	chapoly_aead_t public;
+
+	/**
+	 * IV generator.
+	 */
+	iv_gen_t *iv_gen;
+
+	/**
+	 * Driver backend
+	 */
+	chapoly_drv_t *drv;
+};
+
+/**
+ * Include a partial block to ICV by padding it with zero bytes
+ */
+static bool poly_update_padded(private_chapoly_aead_t *this,
+							   u_char *in, size_t len)
+{
+	u_char b[POLY_BLOCK_SIZE];
+
+	memset(b, 0, sizeof(b));
+	memcpy(b, in, len);
+
+	return this->drv->poly(this->drv, b, 1);
+}
+
+/**
+ * Include associated data with padding to ICV
+ */
+static bool poly_head(private_chapoly_aead_t *this, u_char *assoc, size_t len)
+{
+	u_int blocks, rem;
+
+	blocks = len / POLY_BLOCK_SIZE;
+	rem = len % POLY_BLOCK_SIZE;
+	if (!this->drv->poly(this->drv, assoc, blocks))
+	{
+		return FALSE;
+	}
+	if (rem)
+	{
+		return poly_update_padded(this, assoc + blocks * POLY_BLOCK_SIZE, rem);
+	}
+	return TRUE;
+}
+
+/**
+ * Include length fields to ICV
+ */
+static bool poly_tail(private_chapoly_aead_t *this, size_t alen, size_t clen)
+{
+	struct {
+		u_int64_t alen;
+		u_int64_t clen;
+	} b;
+
+	b.alen = htole64(alen);
+	b.clen = htole64(clen);
+
+	return this->drv->poly(this->drv, (u_char*)&b, 1);
+}
+
+/**
+ * Perform ChaCha20 encryption inline and generate an ICV tag
+ */
+static bool do_encrypt(private_chapoly_aead_t *this, size_t len, u_char *data,
+					   u_char *iv, size_t alen, u_char *assoc, u_char *icv)
+{
+	u_int blocks, rem, prem;
+
+	if (!this->drv->init(this->drv, iv) ||
+		!poly_head(this, assoc, alen))
+	{
+		return FALSE;
+	}
+	blocks = len / CHACHA_BLOCK_SIZE;
+	if (!this->drv->encrypt(this->drv, data, blocks))
+	{
+		return FALSE;
+	}
+	rem = len % CHACHA_BLOCK_SIZE;
+	if (rem)
+	{
+		u_char stream[CHACHA_BLOCK_SIZE];
+
+		data += blocks * CHACHA_BLOCK_SIZE;
+		if (!this->drv->chacha(this->drv, stream))
+		{
+			return FALSE;
+		}
+		memxor(data, stream, rem);
+
+		blocks = rem / POLY_BLOCK_SIZE;
+		if (!this->drv->poly(this->drv, data, blocks))
+		{
+			return FALSE;
+		}
+		prem = rem % POLY_BLOCK_SIZE;
+		if (prem)
+		{
+			poly_update_padded(this, data + blocks * POLY_BLOCK_SIZE, prem);
+		}
+	}
+	return poly_tail(this, alen, len) &&
+		   this->drv->finish(this->drv, icv);
+}
+
+/**
+ * Perform ChaCha20 decryption inline and generate an ICV tag
+ */
+static bool do_decrypt(private_chapoly_aead_t *this, size_t len, u_char *data,
+					   u_char *iv, size_t alen, u_char *assoc, u_char *icv)
+{
+	u_int blocks, rem, prem;
+
+	if (!this->drv->init(this->drv, iv) ||
+		!poly_head(this, assoc, alen))
+	{
+		return FALSE;
+	}
+	blocks = len / CHACHA_BLOCK_SIZE;
+	if (!this->drv->decrypt(this->drv, data, blocks))
+	{
+		return FALSE;
+	}
+	rem = len % CHACHA_BLOCK_SIZE;
+	if (rem)
+	{
+		u_char stream[CHACHA_BLOCK_SIZE];
+
+		data += blocks * CHACHA_BLOCK_SIZE;
+
+		blocks = rem / POLY_BLOCK_SIZE;
+		if (!this->drv->poly(this->drv, data, blocks))
+		{
+			return FALSE;
+		}
+		prem = rem % POLY_BLOCK_SIZE;
+		if (prem)
+		{
+			poly_update_padded(this, data + blocks * POLY_BLOCK_SIZE, prem);
+		}
+		if (!this->drv->chacha(this->drv, stream))
+		{
+			return FALSE;
+		}
+		memxor(data, stream, rem);
+	}
+	return poly_tail(this, alen, len) &&
+		   this->drv->finish(this->drv, icv);
+}
+
+METHOD(aead_t, encrypt, bool,
+	private_chapoly_aead_t *this, chunk_t plain, chunk_t assoc, chunk_t iv,
+	chunk_t *encr)
+{
+	u_char *out;
+
+	if (sizeof(plain.len) > sizeof(u_int32_t) && plain.len > P_MAX)
+	{
+		return FALSE;
+	}
+	if (iv.len != CHACHA_IV_SIZE)
+	{
+		return FALSE;
+	}
+	out = plain.ptr;
+	if (encr)
+	{
+		*encr = chunk_alloc(plain.len + POLY_ICV_SIZE);
+		out = encr->ptr;
+		memcpy(out, plain.ptr, plain.len);
+	}
+	do_encrypt(this, plain.len, out, iv.ptr, assoc.len, assoc.ptr,
+			   out + plain.len);
+	return TRUE;
+}
+
+METHOD(aead_t, decrypt, bool,
+	private_chapoly_aead_t *this, chunk_t encr, chunk_t assoc, chunk_t iv,
+	chunk_t *plain)
+{
+	u_char *out, icv[POLY_ICV_SIZE];
+	if (iv.len != CHACHA_IV_SIZE || encr.len < POLY_ICV_SIZE)
+	{
+		return FALSE;
+	}
+	encr.len -= POLY_ICV_SIZE;
+	if (sizeof(encr.len) > sizeof(u_int32_t) && encr.len > P_MAX)
+	{
+		return FALSE;
+	}
+	out = encr.ptr;
+	if (plain)
+	{
+		*plain = chunk_alloc(encr.len);
+		out = plain->ptr;
+		memcpy(out, encr.ptr, encr.len);
+	}
+	do_decrypt(this, encr.len, out, iv.ptr, assoc.len, assoc.ptr, icv);
+	return memeq_const(icv, encr.ptr + encr.len, POLY_ICV_SIZE);
+}
+
+METHOD(aead_t, get_block_size, size_t,
+	private_chapoly_aead_t *this)
+{
+	return 1;
+}
+
+METHOD(aead_t, get_icv_size, size_t,
+	private_chapoly_aead_t *this)
+{
+	return POLY_ICV_SIZE;
+}
+
+METHOD(aead_t, get_iv_size, size_t,
+	private_chapoly_aead_t *this)
+{
+	return CHACHA_IV_SIZE;
+}
+
+METHOD(aead_t, get_iv_gen, iv_gen_t*,
+	private_chapoly_aead_t *this)
+{
+	return this->iv_gen;
+}
+
+METHOD(aead_t, get_key_size, size_t,
+	private_chapoly_aead_t *this)
+{
+	return CHACHA_KEY_SIZE + CHACHA_SALT_SIZE;
+}
+
+METHOD(aead_t, set_key, bool,
+	private_chapoly_aead_t *this, chunk_t key)
+{
+	if (key.len != CHACHA_KEY_SIZE + CHACHA_SALT_SIZE)
+	{
+		return FALSE;
+	}
+	return this->drv->set_key(this->drv, "expand 32-byte k",
+							  key.ptr, key.ptr + CHACHA_KEY_SIZE);
+}
+
+METHOD(aead_t, destroy, void,
+	private_chapoly_aead_t *this)
+{
+	this->drv->destroy(this->drv);
+	this->iv_gen->destroy(this->iv_gen);
+	free(this);
+}
+
+/**
+ * See header
+ */
+chapoly_aead_t *chapoly_aead_create(encryption_algorithm_t algo,
+									size_t key_size, size_t salt_size)
+{
+	private_chapoly_aead_t *this;
+	chapoly_drv_t *drv;
+
+	if (algo != ENCR_CHACHA20_POLY1305)
+	{
+		return NULL;
+	}
+	if (key_size && key_size != CHACHA_KEY_SIZE)
+	{
+		return NULL;
+	}
+	if (salt_size && salt_size != CHACHA_SALT_SIZE)
+	{
+		return NULL;
+	}
+	drv = chapoly_drv_probe();
+	if (!drv)
+	{
+		return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.aead = {
+				.encrypt = _encrypt,
+				.decrypt = _decrypt,
+				.get_block_size = _get_block_size,
+				.get_icv_size = _get_icv_size,
+				.get_iv_size = _get_iv_size,
+				.get_iv_gen = _get_iv_gen,
+				.get_key_size = _get_key_size,
+				.set_key = _set_key,
+				.destroy = _destroy,
+			},
+		},
+		.iv_gen = iv_gen_seq_create(),
+		.drv = drv,
+	);
+
+	return &this->public;
+}

src/libstrongswan/plugins/chapoly/chapoly_aead.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup chapoly_aead chapoly_aead
+ * @{ @ingroup chapoly
+ */
+
+#ifndef CHAPOLY_AEAD_H_
+#define CHAPOLY_AEAD_H_
+
+#include <crypto/aead.h>
+
+typedef struct chapoly_aead_t chapoly_aead_t;
+
+/**
+ * ChaCha20/Poly1305 AEAD implementation.
+ *
+ * TODO-Chapoly: draft-ietf-ipsecme-chacha20-poly1305-05
+ */
+struct chapoly_aead_t {
+
+	/**
+	 * Implements aead_t interface.
+	 */
+	aead_t aead;
+};
+
+/**
+ * Create a chapoly_aead instance.
+ *
+ * @param algo			algorithm to implement, ENCR_CHACHA20_POLY1305
+ * @param key_size		key size in bytes, 32
+ * @param salt_size		size of implicit salt length, 0
+ * @return				AEAD, NULL if not supported
+ */
+chapoly_aead_t *chapoly_aead_create(encryption_algorithm_t algo,
+									size_t key_size, size_t salt_size);
+
+#endif /** CHAPOLY_AEAD_H_ @}*/

src/libstrongswan/plugins/chapoly/chapoly_drv.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "chapoly_drv.h"
+
+typedef chapoly_drv_t*(*chapoly_drv_create)();
+
+/**
+ * See header.
+ */
+chapoly_drv_t *chapoly_drv_probe()
+{
+	chapoly_drv_create drivers[] = {
+	};
+	chapoly_drv_t *driver;
+	int i;
+
+	for (i = 0; i < countof(drivers); i++)
+	{
+		driver = drivers[i]();
+		if (driver)
+		{
+			return driver;
+		}
+	}
+	return NULL;
+}

src/libstrongswan/plugins/chapoly/chapoly_drv.h

@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup chapoly_drv chapoly_drv
+ * @{ @ingroup chapoly
+ */
+
+#ifndef CHAPOLY_DRV_H_
+#define CHAPOLY_DRV_H_
+
+#include <library.h>
+
+#define CHACHA_BLOCK_SIZE 64
+#define CHACHA_IV_SIZE 8
+#define CHACHA_SALT_SIZE 4
+#define CHACHA_KEY_SIZE 32
+#define POLY_BLOCK_SIZE 16
+#define POLY_ICV_SIZE 16
+
+typedef struct chapoly_drv_t chapoly_drv_t;
+
+/**
+ * ChaCha20/Poly1305 backend implementation.
+ */
+struct chapoly_drv_t {
+
+	/**
+	 * Set the ChaCha20 encryption key.
+	 *
+	 * @param constant		16 byte key constant to use
+	 * @param key			32 byte encryption key
+	 * @param salt			4 byte nonce salt
+	 * @return				TRUE if key set
+	 */
+	bool (*set_key)(chapoly_drv_t *this, u_char *constant, u_char *key,
+					u_char *salt);
+
+	/**
+	 * Start an AEAD en/decryption session, reset state.
+	 *
+	 * @param iv			8 byte initialization vector for nonce
+	 * @return				TRUE if initialized
+	 */
+	bool (*init)(chapoly_drv_t *this, u_char *iv);
+
+	/**
+	 * Poly1305 update multiple blocks.
+	 *
+	 * @param data			data to update Poly1305 for
+	 * @param blocks		number of 16-byte blocks to process
+	 * @return				TRUE if updated
+	 */
+	bool (*poly)(chapoly_drv_t *this, u_char *data, u_int blocks);
+
+	/**
+	 * Create a single ChaCha20 keystream block.
+	 *
+	 * @param stream		64-byte block to write key stream data to
+	 * @return				TRUE if keystream returned
+	 */
+	bool (*chacha)(chapoly_drv_t *this, u_char *stream);
+
+	/**
+	 * Encrypt multiple blocks of data inline, update Poly1305.
+	 *
+	 * @param data			data to process
+	 * @param blocks		number of 64-byte blocks to process
+	 * @return				TRUE if encrypted
+	 */
+	bool (*encrypt)(chapoly_drv_t *this, u_char *data, u_int blocks);
+
+	/**
+	 * Decrypt multiple blocks of data inline, update Poly1305.
+	 *
+	 * @param data			data to process
+	 * @param blocks		number of 64-byte blocks to process
+	 * @return				TRUE if decrypted
+	 */
+	bool (*decrypt)(chapoly_drv_t *this, u_char *data, u_int blocks);
+
+	/**
+	 * End a AEAD encryption session, return MAC.
+	 *
+	 * @param mac			16-byte block to write MAC to
+	 * @return				TRUE if MAC returned
+	 */
+	bool (*finish)(chapoly_drv_t *this, u_char *mac);
+
+	/**
+	 * Destroy a chapoly_drv_t.
+	 */
+	void (*destroy)(chapoly_drv_t *this);
+};
+
+/**
+ * Create a chapoly_drv instance.
+ */
+chapoly_drv_t *chapoly_drv_probe();
+
+#endif /** CHAPOLY_DRV_H_ @}*/

src/libstrongswan/plugins/chapoly/chapoly_plugin.c

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "chapoly_plugin.h"
+#include "chapoly_aead.h"
+
+#include <library.h>
+
+typedef struct private_chapoly_plugin_t private_chapoly_plugin_t;
+
+/**
+ * Private data of chapoly_plugin
+ */
+struct private_chapoly_plugin_t {
+
+	/**
+	 * Public functions
+	 */
+	chapoly_plugin_t public;
+};
+
+METHOD(plugin_t, get_name, char*,
+	private_chapoly_plugin_t *this)
+{
+	return "chapoly";
+}
+
+METHOD(plugin_t, get_features, int,
+	private_chapoly_plugin_t *this, plugin_feature_t *features[])
+{
+	static plugin_feature_t f[] = {
+		PLUGIN_REGISTER(AEAD, chapoly_aead_create),
+			PLUGIN_PROVIDE(AEAD, ENCR_CHACHA20_POLY1305, 32),
+	};
+	*features = f;
+	return countof(f);
+}
+
+METHOD(plugin_t, destroy, void,
+	private_chapoly_plugin_t *this)
+{
+	free(this);
+}
+
+/*
+ * see header file
+ */
+plugin_t *chapoly_plugin_create()
+{
+	private_chapoly_plugin_t *this;
+
+	INIT(this,
+		.public = {
+			.plugin = {
+				.get_name = _get_name,
+				.get_features = _get_features,
+				.destroy = _destroy,
+			},
+		},
+	);
+
+	return &this->public.plugin;
+}

src/libstrongswan/plugins/chapoly/chapoly_plugin.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup chapoly chapoly
+ * @ingroup plugins
+ *
+ * @defgroup chapoly_plugin chapoly_plugin
+ * @{ @ingroup chapoly
+ */
+
+#ifndef CHAPOLY_PLUGIN_H_
+#define CHAPOLY_PLUGIN_H_
+
+#include <plugins/plugin.h>
+
+typedef struct chapoly_plugin_t chapoly_plugin_t;
+
+/**
+ * Plugin providing a ChaCha20/Poly1305 AEAD.
+ */
+struct chapoly_plugin_t {
+
+	/**
+	 * Implements plugin interface.
+	 */
+	plugin_t plugin;
+};
+
+#endif /** CHAPOLY_PLUGIN_H_ @}*/