From fc8c8d82f05911836208cc9169e103d5578ffd70 Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Mon, 28 Oct 2013 18:27:10 +0100 Subject: Unify duplicate code in xsalsa20-poly1305 and aes128-gcm methods --- src/methods/aes128_gcm/aes128_gcm.c | 115 +++++++----------------------------- 1 file changed, 21 insertions(+), 94 deletions(-) (limited to 'src/methods/aes128_gcm') diff --git a/src/methods/aes128_gcm/aes128_gcm.c b/src/methods/aes128_gcm/aes128_gcm.c index 46dba5c..610df7c 100644 --- a/src/methods/aes128_gcm/aes128_gcm.c +++ b/src/methods/aes128_gcm/aes128_gcm.c @@ -26,57 +26,21 @@ #include #include +#include "../common.h" #define KEYBYTES 16 -#define NONCEBYTES 7 struct fastd_method_session_state { - struct timespec valid_till; - struct timespec refresh_after; - - uint8_t send_nonce[NONCEBYTES]; - uint8_t receive_nonce[NONCEBYTES]; - - struct timespec receive_last; - uint64_t receive_reorder_seen; + fastd_method_common_t common; fastd_crypto_aes128ctr_state_t *cstate_aes128ctr; fastd_crypto_ghash_state_t *cstate_ghash; }; -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_t *ctx) { - return (fastd_max_packet_size(ctx) + NONCEBYTES + sizeof(fastd_block128_t)); + return (fastd_max_packet_size(ctx) + COMMON_NONCEBYTES + sizeof(fastd_block128_t)); } @@ -98,18 +62,12 @@ static size_t method_min_decrypt_tail_space(fastd_context_t *ctx UNUSED) { static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, uint8_t *secret, size_t length, bool initiator) { - int i; - if (length < KEYBYTES) exit_bug(ctx, "aes128-gcm: tried to init with short secret"); fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t)); - 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 - fastd_rand(ctx, 0, ctx->conf->key_refresh_splay); + fastd_method_common_init(ctx, &session->common, initiator); fastd_block128_t key; memcpy(key.b, secret, sizeof(fastd_block128_t)); @@ -122,39 +80,27 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, u session->cstate_ghash = ctx->conf->crypto_ghash->set_h(ctx, ctx->crypto_ghash, &H); - 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_t *ctx, fastd_method_session_state_t *session) { - return (session && timespec_after(&session->valid_till, &ctx->now)); + 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 (session->send_nonce[0] & 1); + 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 timespec_after(&ctx->now, &session->refresh_after); + 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) { - struct timespec valid_max = ctx->now; - valid_max.tv_sec += ctx->conf->key_valid_old; - - if (timespec_after(&session->valid_till, &valid_max)) - session->valid_till = valid_max; + 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) { + if (session) { ctx->conf->crypto_aes128ctr->free_state(ctx, session->cstate_aes128ctr); ctx->conf->crypto_ghash->free_state(ctx, session->cstate_ghash); @@ -177,14 +123,14 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast 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(NONCEBYTES, 16), sizeof(fastd_block128_t)+tail_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->send_nonce, NONCEBYTES); - memset(nonce.b+NONCEBYTES, 0, sizeof(fastd_block128_t)-NONCEBYTES-1); + 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); @@ -215,38 +161,30 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast fastd_buffer_free(in); - fastd_buffer_pull_head(ctx, out, NONCEBYTES); - memcpy(out->data, session->send_nonce, NONCEBYTES); - increment_nonce(session->send_nonce); + 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 < NONCEBYTES+sizeof(fastd_block128_t)) + 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, NONCEBYTES); - memset(nonce.b+NONCEBYTES, 0, sizeof(fastd_block128_t)-NONCEBYTES-1); + 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 (!is_nonce_valid(nonce.b, session->receive_nonce, &age)) + if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce.b, &age)) return false; - if (age >= 0) { - if (timespec_diff(&ctx->now, &session->receive_last) > (int)ctx->conf->reorder_time*1000) - return false; - - if (age > ctx->conf->reorder_count) - return false; - } - - fastd_buffer_push_head(ctx, &in, NONCEBYTES); + 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); @@ -277,21 +215,10 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho fastd_buffer_push_head(ctx, out, sizeof(fastd_block128_t)); - if (age < 0) { - session->receive_reorder_seen >>= age; - session->receive_reorder_seen |= (1 >> (age+1)); - memcpy(session->receive_nonce, nonce.b, 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); + if (!fastd_method_reorder_check(ctx, peer, &session->common, nonce.b, age)) { fastd_buffer_free(*out); *out = fastd_buffer_alloc(ctx, 0, 0, 0); } - else { - pr_debug2(ctx, "accepting reordered packet from %P (age %u)", peer, (unsigned)age); - session->receive_reorder_seen |= (1 << (age-1)); - } return true; } -- cgit v1.2.3