Add generic-poly1305 method

1 files changed, 273 insertions, 0 deletions

diff --git a/src/methods/generic_poly1305/generic_poly1305.c b/src/methods/generic_poly1305/generic_poly1305.c
new file mode 100644
index 0000000..fdad118
--- /dev/null
+++ b/src/methods/generic_poly1305/generic_poly1305.c
@@ -0,0 +1,273 @@
+/*
+  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 "../common.h"
+
+#include <crypto_onetimeauth_poly1305.h>
+
+
+#define AUTHBLOCKS (block_count(crypto_onetimeauth_poly1305_KEYBYTES, sizeof(fastd_block128_t)))
+
+
+struct fastd_method_session_state {
+	fastd_method_common_t common;
+
+	const fastd_cipher_t *cipher;
+	const fastd_cipher_context_t *cipher_ctx;
+	fastd_cipher_state_t *cipher_state;
+	size_t ivlen;
+};
+
+
+static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_t **cipher, const fastd_cipher_context_t **cctx) {
+	size_t len = strlen(name);
+
+	if (len < 9)
+		return false;
+
+	if (strcmp(name+len-9, "+poly1305"))
+		return false;
+
+	char cipher_name[len-8];
+	memcpy(cipher_name, name, len-9);
+	cipher_name[len-9] = 0;
+
+	if (ctx) {
+		*cipher = fastd_cipher_get_by_name(ctx, cipher_name, cctx);
+		return *cipher;
+	}
+	else {
+		return fastd_cipher_available(cipher_name);
+	}
+}
+
+
+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_HEADBYTES + crypto_onetimeauth_poly1305_BYTES);
+}
+
+static size_t method_min_encrypt_head_space(fastd_context_t *ctx UNUSED) {
+	return AUTHBLOCKS*sizeof(fastd_block128_t);
+}
+
+static size_t method_min_decrypt_head_space(fastd_context_t *ctx UNUSED) {
+	return AUTHBLOCKS*sizeof(fastd_block128_t) - crypto_onetimeauth_poly1305_BYTES;
+}
+
+static size_t method_min_tail_space(fastd_context_t *ctx UNUSED) {
+	return (sizeof(fastd_block128_t)-1);
+}
+
+
+static size_t method_key_length(fastd_context_t *ctx, const char *name) {
+	const fastd_cipher_t *cipher = NULL;
+	const fastd_cipher_context_t *cctx;
+	if (!cipher_get(ctx, name, &cipher, &cctx))
+		exit_bug(ctx, "generic-poly1305: can't get cipher key length");
+
+	return cipher->key_length(ctx, cctx);
+}
+
+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-poly1305: can't instanciate cipher");
+
+	session->cipher_state = session->cipher->init_state(ctx, session->cipher_ctx, secret);
+
+	session->ivlen = session->cipher->iv_length(ctx, session->cipher_state);
+	if (session->ivlen <= COMMON_NONCEBYTES)
+		exit_bug(ctx, "generic-poly1305: iv_length to small");
+
+	return session;
+}
+
+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);
+		free(session);
+	}
+}
+
+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, AUTHBLOCKS*sizeof(fastd_block128_t));
+	memset(in.data, 0, AUTHBLOCKS*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_HEADBYTES, 16), sizeof(fastd_block128_t)+tail_len);
+
+	if (tail_len)
+		memset(in.data+in.len, 0, tail_len);
+
+	uint8_t nonce[session->ivlen];
+	memset(nonce, 0, session->ivlen);
+	memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
+	nonce[session->ivlen-1] = 1;
+
+	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
+
+	fastd_block128_t *inblocks = in.data;
+	fastd_block128_t *outblocks = out->data;
+	uint8_t tag[crypto_onetimeauth_poly1305_BYTES];
+
+	bool ok = session->cipher->crypt(ctx, session->cipher_state, outblocks, inblocks, n_blocks*sizeof(fastd_block128_t), nonce);
+
+	if (!ok) {
+		/* restore original buffer */
+		fastd_buffer_push_head(ctx, &in, AUTHBLOCKS*sizeof(fastd_block128_t));
+		fastd_buffer_free(*out);
+		return false;
+	}
+
+	crypto_onetimeauth_poly1305(tag, (const uint8_t*)(outblocks+AUTHBLOCKS), in.len - AUTHBLOCKS*sizeof(fastd_block128_t), (const uint8_t*)outblocks);
+
+	fastd_buffer_push_head(ctx, out, AUTHBLOCKS*sizeof(fastd_block128_t) - crypto_onetimeauth_poly1305_BYTES);
+	memcpy(out->data, tag, crypto_onetimeauth_poly1305_BYTES);
+
+	fastd_buffer_free(in);
+
+	fastd_buffer_pull_head(ctx, out, COMMON_HEADBYTES);
+
+	memcpy(out->data, session->common.send_nonce, COMMON_NONCEBYTES);
+	fastd_method_increment_nonce(&session->common);
+
+	((uint8_t*)out->data)[COMMON_NONCEBYTES] = 0; /* flags */
+
+	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_HEADBYTES+crypto_onetimeauth_poly1305_BYTES)
+		return false;
+
+	if (!method_session_is_valid(ctx, session))
+		return false;
+
+	if (((const uint8_t*)in.data)[COMMON_NONCEBYTES]) /* flags */
+		return false;
+
+	uint8_t nonce[session->ivlen];
+	memset(nonce, 0, session->ivlen);
+	memcpy(nonce, in.data, COMMON_NONCEBYTES);
+	nonce[session->ivlen-1] = 1;
+
+	int64_t age;
+	if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce, &age))
+		return false;
+
+	fastd_buffer_push_head(ctx, &in, COMMON_HEADBYTES);
+
+	uint8_t tag[crypto_onetimeauth_poly1305_BYTES];
+	memcpy(tag, in.data, crypto_onetimeauth_poly1305_BYTES);
+
+	fastd_buffer_pull_head(ctx, &in, AUTHBLOCKS*sizeof(fastd_block128_t) - crypto_onetimeauth_poly1305_BYTES);
+	memset(in.data, 0, AUTHBLOCKS*sizeof(fastd_block128_t));
+
+	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 = block_count(in.len, sizeof(fastd_block128_t));
+	fastd_block128_t *inblocks = in.data;
+	fastd_block128_t *outblocks = out->data;
+
+	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);
+
+		ok = (crypto_onetimeauth_poly1305_verify(tag, in.data+AUTHBLOCKS*sizeof(fastd_block128_t), in.len - AUTHBLOCKS*sizeof(fastd_block128_t), out->data) == 0);
+	}
+
+	if (!ok) {
+		fastd_buffer_free(*out);
+
+		/* restore input buffer */
+		fastd_buffer_push_head(ctx, &in, AUTHBLOCKS*sizeof(fastd_block128_t) - crypto_onetimeauth_poly1305_BYTES);
+		memcpy(in.data, tag, crypto_onetimeauth_poly1305_BYTES);
+		fastd_buffer_pull_head(ctx, &in, COMMON_HEADBYTES);
+		memcpy(in.data, nonce, COMMON_NONCEBYTES);
+		((uint8_t*)in.data)[COMMON_NONCEBYTES] = 0;
+
+		return false;
+	}
+
+	fastd_buffer_free(in);
+
+	fastd_buffer_push_head(ctx, out, AUTHBLOCKS*sizeof(fastd_block128_t));
+
+	if (!fastd_method_reorder_check(ctx, peer, &session->common, nonce, age)) {
+		fastd_buffer_free(*out);
+		*out = fastd_buffer_alloc(ctx, 0, 0, 0);
+	}
+
+	return true;
+}
+
+const fastd_method_t fastd_method_generic_poly1305 = {
+	.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_tail_space,
+	.min_decrypt_tail_space = method_min_tail_space,
+
+	.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,
+};