From ce047dd5b1beaba66b8ea615191c421e1c8c8c9a Mon Sep 17 00:00:00 2001 From: Kévin Le Gouguec Date: Tue, 30 Apr 2019 15:41:59 +0200 Subject: Homogénéisation de la gestion de l'index de bloc dans les tweaks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit - "block number" → "block index" - "192" → "t" - boucle de copie de l'index - utilisation de size_t : - par définition, aucune implémentation ne pourra traiter plus d'octets que SIZE_MAX (donc pas plus de blocs), - pas de raison de forcer un index de 64 bits sur ces pauvres ATmega et MSP430. --- src/ref/lilliput-ii.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) (limited to 'src/ref/lilliput-ii.c') diff --git a/src/ref/lilliput-ii.c b/src/ref/lilliput-ii.c index a371521..6811d49 100644 --- a/src/ref/lilliput-ii.c +++ b/src/ref/lilliput-ii.c @@ -28,37 +28,38 @@ This file implements Lilliput-AE's nonce-misuse-resistant mode based on SCT-2. static void _init_msg_tweak(const uint8_t tag[TAG_BYTES], uint8_t tweak[TWEAK_BYTES]) { - /* The t-bit tweak is filled as follows: + /* With an s-bit block index, the t-bit tweak is filled as follows: * * - bits [ 1, t-1]: tag + block index - * [ 1, 64]: tag[ 1.. 64] XOR block index - * [ 65, t-1]: tag[65..t-1] + * [ 1, s]: tag[1..s] XOR block index + * [s+1, t-1]: tag[s+1..t-1] * - bit t: 1 * - * This function sets bits 65 to t once and for all. + * This function sets bits s+1 to t once and for all. */ - memcpy(tweak+sizeof(uint64_t), tag+sizeof(uint64_t), TAG_BYTES-sizeof(uint64_t)); + memcpy(tweak+sizeof(size_t), tag+sizeof(size_t), TAG_BYTES-sizeof(size_t)); tweak[TWEAK_BYTES-1] |= 0x80; } -static void _fill_msg_tweak(const uint8_t tag[TAG_BYTES], uint64_t block_index, uint8_t tweak[TWEAK_BYTES]) +static void _fill_msg_tweak(const uint8_t tag[TAG_BYTES], size_t block_index, uint8_t tweak[TWEAK_BYTES]) { - /* The t-bit tweak is filled as follows: + /* With an s-bit block index, the t-bit tweak is filled as follows: * * - bits [ 1, t-1]: tag + block index - * [ 1, 64]: tag[ 1.. 64] XOR block index - * [ 65, t-1]: tag[65..t-1] + * [ 1, s]: tag[1..s] XOR block index + * [s+1, t-1]: tag[s+1..t-1] * - bit t: 1 * - * This function assumes bits 65 to t have already been set, and - * only sets bits 1 to 64. + * This function assumes bits s+1 to t have already been set, and + * only sets bits 1 to s. */ + copy_block_index(block_index, tweak); + for (size_t i=0; i> i*8 & 0xff; - tweak[i] = tag[i] ^ index_i; + tweak[i] ^= tag[i]; } } -- cgit v1.2.3