Add generic-umac and composed-umac methods based on UMAC

1 files changed, 308 insertions, 0 deletions

diff --git a/src/methods/composed_umac/composed_umac.c b/src/methods/composed_umac/composed_umac.c
new file mode 100644
index 0000000..02fdda6
--- /dev/null
+++ b/src/methods/composed_umac/composed_umac.c
@@ -0,0 +1,308 @@
+/*
+  Copyright (c) 2012-2014, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/**
+   \file
+
+   composed-umac method provider
+
+   composed-umac combines any cipher (or null) with UMAC, while another cipher is
+   used to generate the UHASH keys. Combining the null cipher with UMAC allows creating
+   unencrypted, authenticated-only methods.
+*/
+
+
+#include "../../crypto.h"
+#include "../../method.h"
+#include "../common.h"
+
+
+/** A block of zeros */
+static const fastd_block128_t ZERO_BLOCK = {};
+
+
+/** A specific method provided by this provider */
+struct fastd_method {
+	const fastd_cipher_info_t *cipher_info;		/**< The cipher used for encryption */
+	const fastd_cipher_info_t *umac_cipher_info;	/**< The cipher used for authenticaton */
+	const fastd_mac_info_t *uhash_info;		/**< UHASH */
+};
+
+/** The method-specific session state */
+struct fastd_method_session_state {
+	fastd_method_common_t common;			/**< The common method state */
+
+	const fastd_method_t *method;			/**< The specific method used */
+
+	const fastd_cipher_t *cipher;			/**< The cipher implementation used for encryption */
+	fastd_cipher_state_t *cipher_state;		/**< The cipher state for encryption */
+
+	const fastd_cipher_t *umac_cipher;		/**< The cipher implementation used for authentication */
+	fastd_cipher_state_t *umac_cipher_state;	/**< The cipher state for authentication */
+
+	const fastd_mac_t *uhash;			/**< The UHASH implementation */
+	fastd_mac_state_t *uhash_state;			/**< The UHASH state */
+};
+
+
+/** Instanciates a method using a name of the pattern "<cipher>+<cipher>+umac" (or "<cipher>+<cipher>-umac" for block ciphers in counter mode, e.g. null+aes128-umac instead of null+aes128-ctr+umac) */
+static bool method_create_by_name(const char *name, fastd_method_t **method) {
+	fastd_method_t m;
+
+	m.uhash_info = fastd_mac_info_get_by_name("uhash");
+	if (!m.uhash_info)
+		return false;
+
+	size_t len = strlen(name);
+	char cipher_name[len];
+
+	if (len >= 5 && !strcmp(name+len-5, "+umac")) {
+		memcpy(cipher_name, name, len-5);
+		cipher_name[len-5] = 0;
+	}
+	else {
+		return false;
+	}
+
+	char *umac_cipher_name = strchr(cipher_name, '+');
+
+	if (!umac_cipher_name)
+		return false;
+
+	*umac_cipher_name = 0;
+	umac_cipher_name++;
+
+	m.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!m.cipher_info)
+		return false;
+
+	if (m.cipher_info->iv_length && m.cipher_info->iv_length <= COMMON_NONCEBYTES)
+		return false;
+
+	m.umac_cipher_info = fastd_cipher_info_get_by_name(umac_cipher_name);
+	if (!m.umac_cipher_info)
+		return false;
+
+	if (m.umac_cipher_info->iv_length <= COMMON_NONCEBYTES)
+		return false;
+
+	*method = fastd_new(fastd_method_t);
+	**method = m;
+
+	return true;
+}
+
+/** Frees a method */
+static void method_destroy(fastd_method_t *method) {
+	free(method);
+}
+
+/** Returns the key length used by a method */
+static size_t method_key_length(const fastd_method_t *method) {
+	return method->cipher_info->key_length + method->umac_cipher_info->key_length + method->uhash_info->key_length;
+}
+
+/** Initializes a session */
+static fastd_method_session_state_t * method_session_init(const fastd_method_t *method, const uint8_t *secret, bool initiator) {
+	fastd_method_session_state_t *session = fastd_new(fastd_method_session_state_t);
+
+	fastd_method_common_init(&session->common, initiator);
+	session->method = method;
+
+	session->cipher = fastd_cipher_get(method->cipher_info);
+	session->cipher_state = session->cipher->init(secret);
+
+	session->umac_cipher = fastd_cipher_get(method->umac_cipher_info);
+	session->umac_cipher_state = session->umac_cipher->init(secret + method->cipher_info->key_length);
+
+	session->uhash = fastd_mac_get(method->uhash_info);
+	session->uhash_state = session->uhash->init(secret + method->cipher_info->key_length + method->umac_cipher_info->key_length);
+
+	return session;
+}
+
+/** Checks if the session is currently valid */
+static bool method_session_is_valid(fastd_method_session_state_t *session) {
+	return (session && fastd_method_session_common_is_valid(&session->common));
+}
+
+/** Checks if this side is the initator of the session */
+static bool method_session_is_initiator(fastd_method_session_state_t *session) {
+	return fastd_method_session_common_is_initiator(&session->common);
+}
+
+/** Checks if the session should be refreshed */
+static bool method_session_want_refresh(fastd_method_session_state_t *session) {
+	return fastd_method_session_common_want_refresh(&session->common);
+}
+
+/** Marks the session as superseded */
+static void method_session_superseded(fastd_method_session_state_t *session) {
+	fastd_method_session_common_superseded(&session->common);
+}
+
+/** Frees the session state */
+static void method_session_free(fastd_method_session_state_t *session) {
+	if (session) {
+		session->cipher->free(session->cipher_state);
+		session->umac_cipher->free(session->umac_cipher_state);
+		session->uhash->free(session->uhash_state);
+
+		free(session);
+	}
+}
+
+/** Encrypts and authenticates a packet */
+static bool method_encrypt(fastd_peer_t *peer UNUSED, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+	size_t tail_len = in.len ? alignto(in.len, 2 * sizeof(fastd_block128_t))-in.len : (2 * sizeof(fastd_block128_t));
+
+	*out = fastd_buffer_alloc(sizeof(fastd_block128_t)+in.len, alignto(COMMON_HEADBYTES, 16), sizeof(fastd_block128_t)+tail_len);
+
+	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
+
+	fastd_block128_t *inblocks = in.data;
+	fastd_block128_t *outblocks = out->data;
+	fastd_block128_t tag;
+
+	uint8_t umac_nonce[session->method->umac_cipher_info->iv_length] __attribute__((aligned(8)));
+	fastd_method_expand_nonce(umac_nonce, session->common.send_nonce, sizeof(umac_nonce));
+
+	bool ok = session->umac_cipher->crypt(session->umac_cipher_state, outblocks, &ZERO_BLOCK, sizeof(fastd_block128_t), umac_nonce);
+
+	if (ok) {
+		uint8_t nonce[session->method->cipher_info->iv_length] __attribute__((aligned(8)));
+		fastd_method_expand_nonce(nonce, session->common.send_nonce, sizeof(nonce));
+
+		ok = session->cipher->crypt(session->cipher_state, outblocks+1, inblocks, n_blocks*sizeof(fastd_block128_t), nonce);
+	}
+
+	if (ok) {
+		if (tail_len)
+			memset(out->data+out->len, 0, tail_len);
+
+		ok = session->uhash->digest(session->uhash_state, &tag, outblocks+1, out->len - sizeof(fastd_block128_t));
+	}
+
+	if (!ok) {
+		fastd_buffer_free(*out);
+		return false;
+	}
+
+	xor_a(&outblocks[0], &tag);
+
+	fastd_buffer_free(in);
+
+	fastd_method_put_common_header(out, session->common.send_nonce, 0);
+	fastd_method_increment_nonce(&session->common);
+
+	return true;
+}
+
+/** Verifies and decrypts a packet */
+static bool method_decrypt(fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+	if (in.len < COMMON_HEADBYTES+sizeof(fastd_block128_t))
+		return false;
+
+	if (!method_session_is_valid(session))
+		return false;
+
+	uint8_t in_nonce[COMMON_NONCEBYTES];
+	uint8_t flags;
+	int64_t age;
+	if (!fastd_method_handle_common_header(&session->common, &in, in_nonce, &flags, &age))
+		return false;
+
+	if (flags)
+		return false;
+
+	uint8_t nonce[session->method->cipher_info->iv_length] __attribute__((aligned(8)));
+	fastd_method_expand_nonce(nonce, in_nonce, sizeof(nonce));
+
+	uint8_t umac_nonce[session->method->umac_cipher_info->iv_length] __attribute__((aligned(8)));
+	fastd_method_expand_nonce(umac_nonce, in_nonce, sizeof(umac_nonce));
+
+	size_t in_len = in.len - sizeof(fastd_block128_t);
+	size_t tail_len = in_len ? alignto(in_len, 2 * sizeof(fastd_block128_t))-in_len : (2 * sizeof(fastd_block128_t));
+	*out = fastd_buffer_alloc(in.len, 0, tail_len);
+
+	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
+
+	fastd_block128_t *inblocks = in.data;
+	fastd_block128_t *outblocks = out->data;
+	fastd_block128_t tag;
+
+	bool ok = session->umac_cipher->crypt(session->umac_cipher_state, outblocks, inblocks, sizeof(fastd_block128_t), umac_nonce);
+
+	if (ok)
+		ok = session->cipher->crypt(session->cipher_state, outblocks+1, inblocks+1, (n_blocks-1)*sizeof(fastd_block128_t), nonce);
+
+	if (ok) {
+		if (tail_len)
+			memset(in.data+in.len, 0, tail_len);
+
+		ok = session->uhash->digest(session->uhash_state, &tag, inblocks+1, in_len);
+	}
+
+	if (!ok || memcmp(&tag, &outblocks[0], sizeof(fastd_block128_t)) != 0) {
+		fastd_buffer_free(*out);
+		return false;
+	}
+
+	fastd_buffer_push_head(out, sizeof(fastd_block128_t));
+
+	if (!fastd_method_reorder_check(peer, &session->common, in_nonce, age)) {
+		fastd_buffer_free(*out);
+		*out = fastd_buffer_alloc(0, 0, 0);
+	}
+
+	fastd_buffer_free(in);
+
+	return true;
+}
+
+
+/** The composed-umac method provider */
+const fastd_method_provider_t fastd_method_composed_umac = {
+	.max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
+	.min_encrypt_head_space = 0,
+	.min_decrypt_head_space = 0,
+	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
+	.min_decrypt_tail_space = 2*sizeof(fastd_block128_t),
+
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
+	.key_length = method_key_length,
+
+	.session_init = method_session_init,
+	.session_is_valid = method_session_is_valid,
+	.session_is_initiator = method_session_is_initiator,
+	.session_want_refresh = method_session_want_refresh,
+	.session_superseded = method_session_superseded,
+	.session_free = method_session_free,
+
+	.encrypt = method_encrypt,
+	.decrypt = method_decrypt,
+};