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authorMatthias Schiffer <mschiffer@universe-factory.net>2014-08-28 18:46:02 +0200
committerMatthias Schiffer <mschiffer@universe-factory.net>2014-08-28 18:46:02 +0200
commit46a82c570cf940479be968864eb9638407d7d84f (patch)
tree26fdb9aeaf7cc04a97dfd9470ad24c8053b19e3e /src/methods/generic_umac/generic_umac.c
parenta681219a9275ded66dd927750edcec7859cbffbb (diff)
downloadfastd-46a82c570cf940479be968864eb9638407d7d84f.tar
fastd-46a82c570cf940479be968864eb9638407d7d84f.zip
Add generic-umac and composed-umac methods based on UMAC
Diffstat (limited to 'src/methods/generic_umac/generic_umac.c')
-rw-r--r--src/methods/generic_umac/generic_umac.c267
1 files changed, 267 insertions, 0 deletions
diff --git a/src/methods/generic_umac/generic_umac.c b/src/methods/generic_umac/generic_umac.c
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+++ b/src/methods/generic_umac/generic_umac.c
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+/*
+ 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
+
+ generic-umac method provider
+
+ generic-umac can combine any stream cipher with the UMAC authentication.
+*/
+
+
+#include "../../crypto.h"
+#include "../../method.h"
+#include "../common.h"
+
+
+/** A specific method provided by this provider */
+struct fastd_method {
+ const fastd_cipher_info_t *cipher_info; /**< The cipher used */
+ 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 */
+ fastd_cipher_state_t *cipher_state; /**< The cipher state */
+
+ 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>+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+1];
+
+ if (len >= 5 && !strcmp(name+len-5, "+umac")) {
+ memcpy(cipher_name, name, len-5);
+ cipher_name[len-5] = 0;
+ }
+ else {
+ return false;
+ }
+
+ m.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+ if (!m.cipher_info)
+ return false;
+
+ if (m.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->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->uhash = fastd_mac_get(method->uhash_info);
+ session->uhash_state = session->uhash->init(secret + method->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->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));
+
+ fastd_buffer_pull_head_zero(&in, sizeof(fastd_block128_t));
+
+ *out = fastd_buffer_alloc(in.len, alignto(COMMON_HEADBYTES, 16), tail_len);
+
+ uint8_t nonce[session->method->cipher_info->iv_length] __attribute__((aligned(8)));
+ fastd_method_expand_nonce(nonce, session->common.send_nonce, sizeof(nonce));
+
+ 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->cipher->crypt(session->cipher_state, outblocks, 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));
+
+ 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;
+
+ if (tail_len)
+ memset(in.data+in.len, 0, tail_len);
+
+ bool ok = session->cipher->crypt(session->cipher_state, outblocks, inblocks, n_blocks*sizeof(fastd_block128_t), nonce);
+
+ if (ok)
+ 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_free(in);
+
+ 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);
+ }
+
+ return true;
+}
+
+
+/** The generic-umac method provider */
+const fastd_method_provider_t fastd_method_generic_umac = {
+ .max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
+ .min_encrypt_head_space = sizeof(fastd_block128_t),
+ .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,
+};