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authorMatthias Schiffer <mschiffer@universe-factory.net>2013-11-02 14:34:01 +0100
committerMatthias Schiffer <mschiffer@universe-factory.net>2013-11-02 14:34:01 +0100
commit20a95ef2731ce21acfe5c1ba97b40001217b0216 (patch)
treea41ed017d615a42771113fc9d7ee3df67652620f /src/methods/generic_gcm
parent7a3c8bee42879add84a143ff98f28cbd0251dc7b (diff)
downloadfastd-20a95ef2731ce21acfe5c1ba97b40001217b0216.tar
fastd-20a95ef2731ce21acfe5c1ba97b40001217b0216.zip
Convert aes128-gcm into a generic gcm method
Diffstat (limited to 'src/methods/generic_gcm')
-rw-r--r--src/methods/generic_gcm/CMakeLists.txt6
-rw-r--r--src/methods/generic_gcm/generic_gcm.c283
2 files changed, 289 insertions, 0 deletions
diff --git a/src/methods/generic_gcm/CMakeLists.txt b/src/methods/generic_gcm/CMakeLists.txt
new file mode 100644
index 0000000..1771ee0
--- /dev/null
+++ b/src/methods/generic_gcm/CMakeLists.txt
@@ -0,0 +1,6 @@
+include_directories(${FASTD_SOURCE_DIR}/src ${FASTD_BINARY_DIR})
+
+add_library(method_generic_gcm OBJECT
+ generic_gcm.c
+)
+set_property(TARGET method_generic_gcm PROPERTY COMPILE_FLAGS "${FASTD_CFLAGS}")
diff --git a/src/methods/generic_gcm/generic_gcm.c b/src/methods/generic_gcm/generic_gcm.c
new file mode 100644
index 0000000..479ea83
--- /dev/null
+++ b/src/methods/generic_gcm/generic_gcm.c
@@ -0,0 +1,283 @@
+/*
+ Copyright (c) 2012-2013, 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.
+*/
+
+
+#include "../../fastd.h"
+#include "../../crypto.h"
+#include "../common.h"
+
+
+struct fastd_method_session_state {
+ fastd_method_common_t common;
+
+ const fastd_cipher_t *cipher;
+ fastd_cipher_context_t *cipher_ctx;
+ fastd_cipher_state_t *cipher_state;
+
+ fastd_crypto_ghash_state_t *cstate_ghash;
+};
+
+
+static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_t **cipher, fastd_cipher_context_t **cctx) {
+ size_t len = strlen(name);
+
+ if (len < 4)
+ return NULL;
+
+ if (strcmp(name+len-4, "-gcm"))
+ return NULL;
+
+ char name_ctr[len+1];
+ memcpy(name_ctr, name, len-3);
+ strncpy(name_ctr+len-3, "ctr", 4);
+
+ if (ctx) {
+ *cipher = fastd_cipher_get_by_name(ctx, name_ctr, cctx);
+ return *cipher;
+ }
+ else {
+ return fastd_cipher_available(name_ctr);
+ }
+}
+
+
+static bool method_provides(const char *name) {
+ return cipher_get(NULL, name, NULL, NULL);
+}
+
+static size_t method_max_packet_size(fastd_context_t *ctx) {
+ return (fastd_max_packet_size(ctx) + COMMON_NONCEBYTES + sizeof(fastd_block128_t));
+}
+
+
+static size_t method_min_encrypt_head_space(fastd_context_t *ctx UNUSED) {
+ return sizeof(fastd_block128_t);
+}
+
+static size_t method_min_decrypt_head_space(fastd_context_t *ctx UNUSED) {
+ return 0;
+}
+
+static size_t method_min_encrypt_tail_space(fastd_context_t *ctx UNUSED) {
+ return (sizeof(fastd_block128_t)-1);
+}
+
+static size_t method_min_decrypt_tail_space(fastd_context_t *ctx UNUSED) {
+ return (2*sizeof(fastd_block128_t)-1);
+}
+
+
+static size_t method_key_length(fastd_context_t *ctx UNUSED) {
+ return sizeof(fastd_block128_t);
+}
+
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+ fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
+
+ fastd_method_common_init(ctx, &session->common, initiator);
+
+ if (!cipher_get(ctx, name, &session->cipher, &session->cipher_ctx))
+ exit_bug(ctx, "generic-gcm: can't instanciate cipher");
+
+ session->cipher_state = session->cipher->init_state(ctx, session->cipher_ctx, secret);
+
+ static const fastd_block128_t zeroblock = {};
+ fastd_block128_t H;
+
+ session->cipher->crypt(ctx, session->cipher_state, &H, &zeroblock, sizeof(fastd_block128_t), &zeroblock);
+
+ session->cstate_ghash = ctx->conf->crypto_ghash->set_h(ctx, ctx->crypto_ghash, &H);
+
+ return session;
+}
+
+static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator) {
+ if (length < sizeof(fastd_block128_t))
+ exit_bug(ctx, "generic-gcm: tried to init with short secret");
+
+ return method_session_init(ctx, name, secret, initiator);
+}
+
+static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ return (session && fastd_method_session_common_is_valid(ctx, &session->common));
+}
+
+static bool method_session_is_initiator(fastd_context_t *ctx UNUSED, fastd_method_session_state_t *session) {
+ return fastd_method_session_common_is_initiator(&session->common);
+}
+
+static bool method_session_want_refresh(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ return fastd_method_session_common_want_refresh(ctx, &session->common);
+}
+
+static void method_session_superseded(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ fastd_method_session_common_superseded(ctx, &session->common);
+}
+
+static void method_session_free(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ if (session) {
+ session->cipher->free_state(ctx, session->cipher_state);
+ ctx->conf->crypto_ghash->free_state(ctx, session->cstate_ghash);
+
+ secure_memzero(session, sizeof(fastd_method_session_state_t));
+ free(session);
+ }
+}
+
+static inline void put_size(fastd_block128_t *out, size_t len) {
+ memset(out, 0, sizeof(fastd_block128_t)-5);
+ out->b[sizeof(fastd_block128_t)-5] = len >> 29;
+ out->b[sizeof(fastd_block128_t)-4] = len >> 21;
+ out->b[sizeof(fastd_block128_t)-3] = len >> 13;
+ out->b[sizeof(fastd_block128_t)-2] = len >> 5;
+ out->b[sizeof(fastd_block128_t)-1] = len << 3;
+}
+
+static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+ fastd_buffer_pull_head(ctx, &in, sizeof(fastd_block128_t));
+ memset(in.data, 0, sizeof(fastd_block128_t));
+
+ size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len;
+ *out = fastd_buffer_alloc(ctx, in.len, alignto(COMMON_NONCEBYTES, 16), sizeof(fastd_block128_t)+tail_len);
+
+ if (tail_len)
+ memset(in.data+in.len, 0, tail_len);
+
+ fastd_block128_t nonce;
+ memcpy(nonce.b, session->common.send_nonce, COMMON_NONCEBYTES);
+ memset(nonce.b+COMMON_NONCEBYTES, 0, sizeof(fastd_block128_t)-COMMON_NONCEBYTES-1);
+ nonce.b[sizeof(fastd_block128_t)-1] = 1;
+
+ int n_blocks = (in.len+sizeof(fastd_block128_t)-1)/sizeof(fastd_block128_t);
+
+ fastd_block128_t *inblocks = in.data;
+ fastd_block128_t *outblocks = out->data;
+ fastd_block128_t sig;
+
+ bool ok = session->cipher->crypt(ctx, 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);
+
+ put_size(&outblocks[n_blocks], in.len-sizeof(fastd_block128_t));
+
+ ok = ctx->conf->crypto_ghash->hash(ctx, session->cstate_ghash, &sig, outblocks+1, n_blocks);
+ }
+
+ if (!ok) {
+ /* restore original buffer */
+ fastd_buffer_push_head(ctx, &in, sizeof(fastd_block128_t));
+ fastd_buffer_free(*out);
+ return false;
+ }
+
+ xor_a(&outblocks[0], &sig);
+
+ fastd_buffer_free(in);
+
+ fastd_buffer_pull_head(ctx, out, COMMON_NONCEBYTES);
+ memcpy(out->data, session->common.send_nonce, COMMON_NONCEBYTES);
+ fastd_method_increment_nonce(&session->common);
+
+ return true;
+}
+
+static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+ if (in.len < COMMON_NONCEBYTES+sizeof(fastd_block128_t))
+ return false;
+
+ if (!method_session_is_valid(ctx, session))
+ return false;
+
+ fastd_block128_t nonce;
+ memcpy(nonce.b, in.data, COMMON_NONCEBYTES);
+ memset(nonce.b+COMMON_NONCEBYTES, 0, sizeof(fastd_block128_t)-COMMON_NONCEBYTES-1);
+ nonce.b[sizeof(fastd_block128_t)-1] = 1;
+
+ int64_t age;
+ if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce.b, &age))
+ return false;
+
+ fastd_buffer_push_head(ctx, &in, COMMON_NONCEBYTES);
+
+ size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len;
+ *out = fastd_buffer_alloc(ctx, in.len, 0, tail_len);
+
+ int n_blocks = (in.len+sizeof(fastd_block128_t)-1)/sizeof(fastd_block128_t);
+
+ fastd_block128_t *inblocks = in.data;
+ fastd_block128_t *outblocks = out->data;
+ fastd_block128_t sig;
+
+ bool ok = session->cipher->crypt(ctx, session->cipher_state, outblocks, inblocks, n_blocks*sizeof(fastd_block128_t), &nonce);
+
+ if (ok) {
+ if (tail_len)
+ memset(in.data+in.len, 0, tail_len);
+
+ put_size(&inblocks[n_blocks], in.len-sizeof(fastd_block128_t));
+
+ ok = ctx->conf->crypto_ghash->hash(ctx, session->cstate_ghash, &sig, inblocks+1, n_blocks);
+ }
+
+ if (!ok || memcmp(&sig, &outblocks[0], sizeof(fastd_block128_t)) != 0) {
+ fastd_buffer_free(*out);
+ return false;
+ }
+
+ fastd_buffer_free(in);
+
+ fastd_buffer_push_head(ctx, out, sizeof(fastd_block128_t));
+
+ if (!fastd_method_reorder_check(ctx, peer, &session->common, nonce.b, age)) {
+ fastd_buffer_free(*out);
+ *out = fastd_buffer_alloc(ctx, 0, 0, 0);
+ }
+
+ return true;
+}
+
+const fastd_method_t fastd_method_generic_gcm = {
+ .provides = method_provides,
+
+ .max_packet_size = method_max_packet_size,
+ .min_encrypt_head_space = method_min_encrypt_head_space,
+ .min_decrypt_head_space = method_min_decrypt_head_space,
+ .min_encrypt_tail_space = method_min_encrypt_tail_space,
+ .min_decrypt_tail_space = method_min_decrypt_tail_space,
+
+ .key_length = method_key_length,
+ .session_init = method_session_init,
+ .session_init_compat = method_session_init_compat,
+ .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,
+};