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/*
AES-CCM-128 (rfc 3610)
Copyright (C) Stefan Metzmacher 2012
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#include "../lib/crypto/crypto.h"
#include "lib/util/byteorder.h"
#define M_ ((AES_CCM_128_M - 2) / 2)
#define L_ (AES_CCM_128_L - 1)
static inline void aes_ccm_128_xor(const uint8_t in1[AES_BLOCK_SIZE],
const uint8_t in2[AES_BLOCK_SIZE],
uint8_t out[AES_BLOCK_SIZE])
{
uint8_t i;
for (i = 0; i < AES_BLOCK_SIZE; i++) {
out[i] = in1[i] ^ in2[i];
}
}
void aes_ccm_128_init(struct aes_ccm_128_context *ctx,
const uint8_t K[AES_BLOCK_SIZE],
const uint8_t N[AES_CCM_128_NONCE_SIZE],
size_t a_total, size_t m_total)
{
uint8_t B_0[AES_BLOCK_SIZE];
ZERO_STRUCTP(ctx);
AES_set_encrypt_key(K, 128, &ctx->aes_key);
memcpy(ctx->nonce, N, AES_CCM_128_NONCE_SIZE);
ctx->a_remain = a_total;
ctx->m_remain = m_total;
/*
* prepare B_0
*/
B_0[0] = L_;
B_0[0] += 8 * M_;
if (a_total > 0) {
B_0[0] += 64;
}
memcpy(&B_0[1], ctx->nonce, AES_CCM_128_NONCE_SIZE);
RSIVAL(B_0, (AES_BLOCK_SIZE - AES_CCM_128_L), m_total);
/*
* prepare X_1
*/
AES_encrypt(B_0, ctx->X_i, &ctx->aes_key);
/*
* prepare B_1
*/
if (a_total >= UINT32_MAX) {
RSSVAL(ctx->B_i, 0, 0xFFFF);
RSBVAL(ctx->B_i, 2, a_total);
ctx->B_i_ofs = 10;
} else if (a_total >= 0xFF00) {
RSSVAL(ctx->B_i, 0, 0xFFFE);
RSIVAL(ctx->B_i, 2, a_total);
ctx->B_i_ofs = 6;
} else if (a_total > 0) {
RSSVAL(ctx->B_i, 0, a_total);
ctx->B_i_ofs = 2;
}
ctx->S_i_ofs = AES_BLOCK_SIZE;
}
void aes_ccm_128_update(struct aes_ccm_128_context *ctx,
const uint8_t *v, size_t v_len)
{
size_t *remain;
if (ctx->a_remain > 0) {
remain = &ctx->a_remain;
} else {
remain = &ctx->m_remain;
}
while (v_len > 0) {
size_t n = MIN(AES_BLOCK_SIZE - ctx->B_i_ofs, v_len);
bool more = true;
memcpy(&ctx->B_i[ctx->B_i_ofs], v, n);
v += n;
v_len -= n;
ctx->B_i_ofs += n;
*remain -= n;
if (ctx->B_i_ofs == AES_BLOCK_SIZE) {
more = false;
} else if (*remain == 0) {
more = false;
}
if (more) {
continue;
}
aes_ccm_128_xor(ctx->X_i, ctx->B_i, ctx->B_i);
AES_encrypt(ctx->B_i, ctx->X_i, &ctx->aes_key);
ZERO_STRUCT(ctx->B_i);
ctx->B_i_ofs = 0;
}
}
static void aes_ccm_128_S_i(struct aes_ccm_128_context *ctx,
uint8_t S_i[AES_BLOCK_SIZE],
size_t i)
{
uint8_t A_i[AES_BLOCK_SIZE];
A_i[0] = L_;
memcpy(&A_i[1], ctx->nonce, AES_CCM_128_NONCE_SIZE);
RSIVAL(A_i, (AES_BLOCK_SIZE - AES_CCM_128_L), i);
AES_encrypt(A_i, S_i, &ctx->aes_key);
}
void aes_ccm_128_crypt(struct aes_ccm_128_context *ctx,
uint8_t *m, size_t m_len)
{
while (m_len > 0) {
if (ctx->S_i_ofs == AES_BLOCK_SIZE) {
ctx->S_i_ctr += 1;
aes_ccm_128_S_i(ctx, ctx->S_i, ctx->S_i_ctr);
ctx->S_i_ofs = 0;
}
m[0] ^= ctx->S_i[ctx->S_i_ofs];
m += 1;
m_len -= 1;
ctx->S_i_ofs += 1;
}
}
void aes_ccm_128_digest(struct aes_ccm_128_context *ctx,
uint8_t digest[AES_BLOCK_SIZE])
{
uint8_t S_0[AES_BLOCK_SIZE];
aes_ccm_128_S_i(ctx, S_0, 0);
/*
* note X_i is T here
*/
aes_ccm_128_xor(ctx->X_i, S_0, digest);
ZERO_STRUCT(S_0);
ZERO_STRUCTP(ctx);
}
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