diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/CMakeLists.txt | 4 | ||||
| -rw-r--r-- | src/config.c | 7 | ||||
| -rw-r--r-- | src/method_aes128_gcm.c | 399 |
3 files changed, 410 insertions, 0 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index ea1e8c9..29e3ba5 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -4,6 +4,10 @@ if(WITH_METHOD_XSALSA20_POLY1305) list(APPEND METHODS method_xsalsa20_poly1305.c) endif(WITH_METHOD_XSALSA20_POLY1305) +if(WITH_METHOD_AES128_GCM) + list(APPEND METHODS method_aes128_gcm.c) +endif(WITH_METHOD_AES128_GCM) + include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${FASTD_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR} ${UECC_INCLUDE_DIR} ${NACL_INCLUDE_DIR}) FLEX_TARGET(fastd_config_lex config.l ${CMAKE_CURRENT_BINARY_DIR}/config.ll.c) diff --git a/src/config.c b/src/config.c index 92c7a45..e69abcc 100644 --- a/src/config.c +++ b/src/config.c @@ -48,6 +48,9 @@ extern const fastd_method fastd_method_null; #ifdef WITH_METHOD_XSALSA20_POLY1305 extern const fastd_method fastd_method_xsalsa20_poly1305; #endif +#ifdef WITH_METHOD_AES128_GCM +extern const fastd_method fastd_method_aes128_gcm; +#endif static void default_config(fastd_config *conf) { @@ -140,6 +143,10 @@ bool fastd_config_method(fastd_context *ctx, fastd_config *conf, const char *nam else if (!strcmp(name, "xsalsa20-poly1305")) conf->method = &fastd_method_xsalsa20_poly1305; #endif +#ifdef WITH_METHOD_AES128_GCM + else if (!strcmp(name, "aes128-gcm")) + conf->method = &fastd_method_aes128_gcm; +#endif else return false; diff --git a/src/method_aes128_gcm.c b/src/method_aes128_gcm.c new file mode 100644 index 0000000..139276c --- /dev/null +++ b/src/method_aes128_gcm.c @@ -0,0 +1,399 @@ +/* + Copyright (c) 2012, 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_stream_aes128ctr.h> + + +#define NONCEBYTES 7 +#define BLOCKBYTES 16 + + +struct _fastd_method_session_state { + struct timespec valid_till; + struct timespec refresh_after; + + uint8_t d[crypto_stream_aes128ctr_BEFORENMBYTES]; + uint8_t H[BLOCKBYTES]; + + uint8_t send_nonce[NONCEBYTES]; + uint8_t receive_nonce[NONCEBYTES]; + + struct timespec receive_last; + uint64_t receive_reorder_seen; +}; + + +static inline void increment_nonce(uint8_t nonce[NONCEBYTES]) { + nonce[0] += 2; + + if (nonce[0] == 0 || nonce[0] == 1) { + int i; + for (i = 1; i < NONCEBYTES; i++) { + nonce[i]++; + if (nonce[i] != 0) + break; + } + } +} + +static inline bool is_nonce_valid(const uint8_t nonce[NONCEBYTES], const uint8_t old_nonce[NONCEBYTES], int64_t *age) { + if ((nonce[0] & 1) != (old_nonce[0] & 1)) + return false; + + int i; + *age = 0; + + for (i = NONCEBYTES-1; i >= 0; i--) { + *age *= 256; + *age += old_nonce[i]-nonce[i]; + } + + *age /= 2; + return true; +} + +static size_t method_max_packet_size(fastd_context *ctx) { + return (fastd_max_packet_size(ctx) + NONCEBYTES + BLOCKBYTES); +} + + +static size_t method_min_encrypt_head_space(fastd_context *ctx) { + return 0; +} + +static size_t method_min_decrypt_head_space(fastd_context *ctx) { + return 0; +} + +static fastd_method_session_state* method_session_init(fastd_context *ctx, uint8_t *secret, size_t length, bool initiator) { + int i; + + if (length < crypto_stream_aes128ctr_KEYBYTES) + exit_bug(ctx, "aes128-gcm: tried to init with short secret"); + + fastd_method_session_state *session = malloc(sizeof(fastd_method_session_state)); + + session->valid_till = ctx->now; + session->valid_till.tv_sec += ctx->conf->key_valid; + + session->refresh_after = ctx->now; + session->refresh_after.tv_sec += ctx->conf->key_refresh; + + crypto_stream_aes128ctr_beforenm(session->d, secret); + + uint8_t zerononce[crypto_stream_aes128ctr_NONCEBYTES]; + memset(zerononce, 0, crypto_stream_aes128ctr_NONCEBYTES); + crypto_stream_aes128ctr_afternm(session->H, BLOCKBYTES, zerononce, session->d); + + session->send_nonce[0] = initiator ? 3 : 2; + session->receive_nonce[0] = initiator ? 0 : 1; + + for (i = 1; i < NONCEBYTES; i++) { + session->send_nonce[i] = 0; + session->receive_nonce[i] = 0; + } + + return session; +} + +static bool method_session_is_valid(fastd_context *ctx, fastd_method_session_state *session) { + return (session && timespec_after(&session->valid_till, &ctx->now)); +} + +static bool method_session_is_initiator(fastd_context *ctx, fastd_method_session_state *session) { + return (session->send_nonce[0] & 1); +} + +static bool method_session_want_refresh(fastd_context *ctx, fastd_method_session_state *session) { + return timespec_after(&ctx->now, &session->refresh_after); +} + +static void method_session_free(fastd_context *ctx, fastd_method_session_state *session) { + if(session) { + memset(session, 0, sizeof(fastd_method_session_state)); + free(session); + } +} + +static void sel(uint8_t *out, const uint8_t *r, const uint8_t *s, unsigned int l, unsigned int b) { + unsigned int j; + unsigned int t; + uint8_t bminus1; + + bminus1 = b - 1; + for (j = 0; j < l; ++j) { + t = bminus1 & (r[j] ^ s[j]); + out[j] = s[j] ^ t; + } +} + +static inline void xor(uint8_t *x, const uint8_t *a, const uint8_t *b, unsigned int l) { + int i; + for (i = 0; i < l; i++) + x[i] = a[i] ^ b[i]; +} + +static inline void shl1(uint8_t *x, unsigned int l) { + int i; + uint8_t c = 0; + + for (i = 0; i < l; i++) { + uint8_t c2 = x[i] >> 7; + x[i] = (x[i] << 1) | c; + c = c2; + } +} + +static inline void shr1(uint8_t *x, unsigned int l) { + int i; + uint8_t c = 0; + + for (i = l-1; i >= 0; i--) { + uint8_t c2 = x[i] & 1; + x[i] = (x[i] >> 1) | (c << 7); + c = c2; + } +} + +static const uint8_t p[BLOCKBYTES] = {0x87}; + +static void mul(uint8_t out[BLOCKBYTES], const uint8_t a[BLOCKBYTES], const uint8_t b[BLOCKBYTES]) { + uint8_t out2[2*BLOCKBYTES]; + uint8_t zero[2*BLOCKBYTES]; + uint8_t a2[2*BLOCKBYTES]; + uint8_t b2[BLOCKBYTES]; + + memset(out2, 0, 2*BLOCKBYTES); + memset(zero, 0, 2*BLOCKBYTES); + + memcpy(a2, a, BLOCKBYTES); + memset(a2+BLOCKBYTES, 0, BLOCKBYTES); + + memcpy(b2, b, BLOCKBYTES); + + int i; + for (i = 0; i < 8*BLOCKBYTES; i++) { + uint8_t tmp[2*BLOCKBYTES]; + + sel(tmp, zero, a2, 2*BLOCKBYTES, b2[0]&1); + xor(out2, out2, tmp, 2*BLOCKBYTES); + + shl1(a2, 2*BLOCKBYTES); + shr1(b2, BLOCKBYTES); + } + + uint8_t out3[BLOCKBYTES+1]; + memcpy(out3, out2, BLOCKBYTES); + out3[BLOCKBYTES] = 0; + + uint8_t p2[BLOCKBYTES+1]; + memcpy(p2, p, BLOCKBYTES); + p2[BLOCKBYTES] = 0; + + for (i = 0; i < 8*BLOCKBYTES; i++) { + uint8_t tmp[BLOCKBYTES+1]; + + sel(tmp, zero, p2, BLOCKBYTES+1, out2[BLOCKBYTES]&1); + xor(out3, out3, tmp, BLOCKBYTES+1); + + shl1(p2, BLOCKBYTES+1); + shr1(out2+BLOCKBYTES, BLOCKBYTES); + } + + memcpy(out, out3, BLOCKBYTES); + memcpy(p2, p, BLOCKBYTES); + + for (i = 0; i < 8; i++) { + uint8_t tmp[2]; + + sel(tmp, zero, p2, 2, out3[BLOCKBYTES]&1); + xor(out, out, tmp, 2); + + shl1(p2, BLOCKBYTES); + out3[BLOCKBYTES] >>= 1; + } +} + +#define BLOCKPTR(buf, i) (((uint8_t*)(buf))+i*BLOCKBYTES) + +static bool method_encrypt(fastd_context *ctx, fastd_peer *peer, fastd_method_session_state *session, fastd_buffer *out, fastd_buffer in) { + *out = fastd_buffer_alloc(in.len, NONCEBYTES+BLOCKBYTES, 0); + uint8_t *sig = ((uint8_t*)out->data) - BLOCKBYTES; + + memset(sig, 0, BLOCKBYTES); + + uint8_t nonce[crypto_stream_aes128ctr_NONCEBYTES]; + memcpy(nonce, session->send_nonce, NONCEBYTES); + memset(nonce+NONCEBYTES, 0, crypto_stream_aes128ctr_NONCEBYTES-NONCEBYTES-1); + nonce[crypto_stream_aes128ctr_NONCEBYTES-1] = 1; + + uint8_t stream[in.len+BLOCKBYTES]; + crypto_stream_aes128ctr_afternm(stream, in.len+BLOCKBYTES, nonce, session->d); + + int blocks = (in.len+BLOCKBYTES-1)/BLOCKBYTES; + + int i; + for (i = 0; i < blocks; i++) { + int len = BLOCKBYTES; + if (i == blocks-1) + len = in.len - i*BLOCKBYTES; + + xor(BLOCKPTR(out->data, i), BLOCKPTR(in.data, i), BLOCKPTR(stream, i+1), len); + + xor(sig, sig, BLOCKPTR(out->data, i), len); + mul(sig, sig, session->H); + } + + sig[BLOCKBYTES-8] ^= (in.len >> 53) & 0xff; + sig[BLOCKBYTES-7] ^= (in.len >> 45) & 0xff; + sig[BLOCKBYTES-6] ^= (in.len >> 37) & 0xff; + sig[BLOCKBYTES-5] ^= (in.len >> 29) & 0xff; + sig[BLOCKBYTES-4] ^= (in.len >> 21) & 0xff; + sig[BLOCKBYTES-3] ^= (in.len >> 13) & 0xff; + sig[BLOCKBYTES-2] ^= (in.len >> 5) & 0xff; + sig[BLOCKBYTES-1] ^= (in.len << 3) & 0xff; + mul(sig, sig, session->H); + + xor(sig, sig, stream, BLOCKBYTES); + + fastd_buffer_free(in); + + fastd_buffer_pull_head(out, NONCEBYTES+BLOCKBYTES); + memcpy(out->data, session->send_nonce, NONCEBYTES); + increment_nonce(session->send_nonce); + + return true; +} + +static bool method_decrypt(fastd_context *ctx, fastd_peer *peer, fastd_method_session_state *session, fastd_buffer *out, fastd_buffer in) { + if (in.len < NONCEBYTES+BLOCKBYTES) + return false; + + if (!method_session_is_valid(ctx, session)) + return false; + + uint8_t nonce[crypto_stream_aes128ctr_NONCEBYTES]; + memcpy(nonce, in.data, NONCEBYTES); + memset(nonce+NONCEBYTES, 0, crypto_stream_aes128ctr_NONCEBYTES-NONCEBYTES-1); + nonce[crypto_stream_aes128ctr_NONCEBYTES-1] = 1; + + int64_t age; + if (!is_nonce_valid(nonce, session->receive_nonce, &age)) + return false; + + if (age >= 0) { + if (timespec_diff(&ctx->now, &session->receive_last) > ctx->conf->reorder_time*1000) + return false; + + if (age > ctx->conf->reorder_count) + return false; + } + + fastd_buffer_push_head(&in, NONCEBYTES+BLOCKBYTES); + + *out = fastd_buffer_alloc(in.len, 0, 0); + + uint8_t sig[BLOCKBYTES]; + memset(sig, 0, BLOCKBYTES); + + uint8_t stream[in.len+BLOCKBYTES]; + crypto_stream_aes128ctr_afternm(stream, in.len+BLOCKBYTES, nonce, session->d); + + int blocks = (in.len+BLOCKBYTES-1)/BLOCKBYTES; + + int i; + for (i = 0; i < blocks; i++) { + int len = BLOCKBYTES; + if (i == blocks-1) + len = in.len - i*BLOCKBYTES; + + xor(BLOCKPTR(out->data, i), BLOCKPTR(in.data, i), BLOCKPTR(stream, i+1), len); + + xor(sig, sig, BLOCKPTR(in.data, i), len); + mul(sig, sig, session->H); + } + + sig[BLOCKBYTES-8] ^= (in.len >> 53) & 0xff; + sig[BLOCKBYTES-7] ^= (in.len >> 45) & 0xff; + sig[BLOCKBYTES-6] ^= (in.len >> 37) & 0xff; + sig[BLOCKBYTES-5] ^= (in.len >> 29) & 0xff; + sig[BLOCKBYTES-4] ^= (in.len >> 21) & 0xff; + sig[BLOCKBYTES-3] ^= (in.len >> 13) & 0xff; + sig[BLOCKBYTES-2] ^= (in.len >> 5) & 0xff; + sig[BLOCKBYTES-1] ^= (in.len << 3) & 0xff; + mul(sig, sig, session->H); + + xor(sig, sig, stream, BLOCKBYTES); + + fastd_buffer_pull_head(&in, BLOCKBYTES); + + if (memcmp(sig, in.data, BLOCKBYTES) != 0) { + fastd_buffer_free(*out); + + /* restore input buffer */ + fastd_buffer_pull_head(&in, NONCEBYTES); + + return false; + } + + fastd_buffer_free(in); + + if (age < 0) { + session->receive_reorder_seen >>= age; + session->receive_reorder_seen |= (1 >> (age+1)); + memcpy(session->receive_nonce, nonce, NONCEBYTES); + session->receive_last = ctx->now; + } + else if (age == 0 || session->receive_reorder_seen & (1 << (age-1))) { + pr_debug(ctx, "dropping duplicate packet from %P (age %u)", peer, (unsigned)age); + fastd_buffer_free(*out); + *out = fastd_buffer_alloc(0, 0, 0); + } + else { + pr_debug(ctx, "accepting reordered packet from %P (age %u)", peer, (unsigned)age); + session->receive_reorder_seen |= (1 << (age-1)); + } + + return true; +} + +const fastd_method fastd_method_aes128_gcm = { + .name = "aes128-gcm", + + .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, + + .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_free = method_session_free, + + .encrypt = method_encrypt, + .decrypt = method_decrypt, +}; 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