From 9dacff2507a1e69cecc0ec888d49d296bd9c91b0 Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Sat, 30 Nov 2013 07:17:29 +0100 Subject: generic-poly1305: add helper functions to handle the common header --- src/methods/common.h | 25 +++++++++++++++++ src/methods/generic_poly1305/generic_poly1305.c | 37 ++++++++----------------- 2 files changed, 37 insertions(+), 25 deletions(-) diff --git a/src/methods/common.h b/src/methods/common.h index d3218ae..b5f7272 100644 --- a/src/methods/common.h +++ b/src/methods/common.h @@ -94,4 +94,29 @@ static inline void fastd_method_increment_nonce(fastd_method_common_t *session) } } +static inline void fastd_method_put_common_header(fastd_context_t *ctx, fastd_buffer_t *buffer, const uint8_t nonce[COMMON_NONCEBYTES], uint8_t flags) { + fastd_buffer_pull_head_from(ctx, buffer, &flags, 1); + fastd_buffer_pull_head_from(ctx, buffer, nonce, COMMON_NONCEBYTES); +} + +static inline void fastd_method_take_common_header(fastd_context_t *ctx, fastd_buffer_t *buffer, uint8_t nonce[COMMON_NONCEBYTES], uint8_t *flags) { + fastd_buffer_push_head_to(ctx, buffer, nonce, COMMON_NONCEBYTES); + fastd_buffer_push_head_to(ctx, buffer, flags, 1); +} + +static inline bool fastd_method_handle_common_header(fastd_context_t *ctx, const fastd_method_common_t *session, fastd_buffer_t *buffer, uint8_t nonce[COMMON_NONCEBYTES], uint8_t *flags, int64_t *age) { + fastd_method_take_common_header(ctx, buffer, nonce, flags); + return fastd_method_is_nonce_valid(ctx, session, nonce, age); +} + + +static inline void fastd_method_expand_nonce(uint8_t *buf, const uint8_t nonce[COMMON_NONCEBYTES], size_t len) { + if (!len) + return; + + memset(buf, 0, len); + memcpy(buf, nonce, min_size_t(len, COMMON_NONCEBYTES)); + buf[len-1] = 1; +} + #endif /* _FASTD_METHODS_COMMON_H_ */ diff --git a/src/methods/generic_poly1305/generic_poly1305.c b/src/methods/generic_poly1305/generic_poly1305.c index 608a526..82c5bf1 100644 --- a/src/methods/generic_poly1305/generic_poly1305.c +++ b/src/methods/generic_poly1305/generic_poly1305.c @@ -126,11 +126,8 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast if (tail_len) memset(in.data+in.len, 0, tail_len); - size_t iv_length = session->method->cipher_info->iv_length; - uint8_t nonce[iv_length]; - memset(nonce, 0, iv_length); - memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES); - nonce[iv_length-1] = 1; + uint8_t nonce[session->method->cipher_info->iv_length]; + fastd_method_expand_nonce(nonce, session->common.send_nonce, sizeof(nonce)); int n_blocks = block_count(in.len, sizeof(fastd_block128_t)); @@ -152,13 +149,9 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast fastd_buffer_free(in); - fastd_buffer_pull_head(ctx, out, COMMON_HEADBYTES); - - memcpy(out->data, session->common.send_nonce, COMMON_NONCEBYTES); + fastd_method_put_common_header(ctx, out, session->common.send_nonce, 0); fastd_method_increment_nonce(&session->common); - ((uint8_t*)out->data)[COMMON_NONCEBYTES] = 0; /* flags */ - return true; } @@ -169,20 +162,17 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho if (!method_session_is_valid(ctx, session)) return false; - if (((const uint8_t*)in.data)[COMMON_NONCEBYTES]) /* flags */ + uint8_t in_nonce[COMMON_NONCEBYTES]; + uint8_t flags; + int64_t age; + if (!fastd_method_handle_common_header(ctx, &session->common, &in, in_nonce, &flags, &age)) return false; - size_t iv_length = session->method->cipher_info->iv_length; - uint8_t nonce[iv_length]; - memset(nonce, 0, iv_length); - memcpy(nonce, in.data, COMMON_NONCEBYTES); - nonce[iv_length-1] = 1; - - int64_t age; - if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce, &age)) + if (flags) return false; - fastd_buffer_push_head(ctx, &in, COMMON_HEADBYTES); + uint8_t nonce[session->method->cipher_info->iv_length]; + fastd_method_expand_nonce(nonce, in_nonce, sizeof(nonce)); uint8_t tag[TAGBYTES]; fastd_buffer_push_head_to(ctx, &in, tag, TAGBYTES); @@ -210,10 +200,7 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho /* restore input buffer */ fastd_buffer_push_head(ctx, &in, KEYBYTES); fastd_buffer_pull_head_from(ctx, &in, tag, TAGBYTES); - - fastd_buffer_pull_head(ctx, &in, COMMON_HEADBYTES); - memcpy(in.data, nonce, COMMON_NONCEBYTES); - ((uint8_t*)in.data)[COMMON_NONCEBYTES] = 0; + fastd_method_put_common_header(ctx, &in, in_nonce, 0); return false; } @@ -222,7 +209,7 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho fastd_buffer_push_head(ctx, out, KEYBYTES); - if (!fastd_method_reorder_check(ctx, peer, &session->common, nonce, age)) { + if (!fastd_method_reorder_check(ctx, peer, &session->common, in_nonce, age)) { fastd_buffer_free(*out); *out = fastd_buffer_alloc(ctx, 0, 0, 0); } -- cgit v1.2.3