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171 lines
3.7 KiB
C
171 lines
3.7 KiB
C
/*
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AES-CCM-128 (rfc 3610)
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Copyright (C) Stefan Metzmacher 2012
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "replace.h"
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#include "../lib/crypto/crypto.h"
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#include "lib/util/byteorder.h"
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#define M_ ((AES_CCM_128_M - 2) / 2)
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#define L_ (AES_CCM_128_L - 1)
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static inline void aes_ccm_128_xor(const uint8_t in1[AES_BLOCK_SIZE],
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const uint8_t in2[AES_BLOCK_SIZE],
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uint8_t out[AES_BLOCK_SIZE])
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{
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uint8_t i;
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for (i = 0; i < AES_BLOCK_SIZE; i++) {
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out[i] = in1[i] ^ in2[i];
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}
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}
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void aes_ccm_128_init(struct aes_ccm_128_context *ctx,
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const uint8_t K[AES_BLOCK_SIZE],
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const uint8_t N[AES_CCM_128_NONCE_SIZE],
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size_t a_total, size_t m_total)
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{
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uint8_t B_0[AES_BLOCK_SIZE];
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ZERO_STRUCTP(ctx);
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AES_set_encrypt_key(K, 128, &ctx->aes_key);
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memcpy(ctx->nonce, N, AES_CCM_128_NONCE_SIZE);
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ctx->a_remain = a_total;
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ctx->m_remain = m_total;
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/*
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* prepare B_0
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*/
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B_0[0] = L_;
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B_0[0] += 8 * M_;
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if (a_total > 0) {
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B_0[0] += 64;
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}
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memcpy(&B_0[1], ctx->nonce, AES_CCM_128_NONCE_SIZE);
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RSIVAL(B_0, (AES_BLOCK_SIZE - AES_CCM_128_L), m_total);
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/*
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* prepare X_1
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*/
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AES_encrypt(B_0, ctx->X_i, &ctx->aes_key);
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/*
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* prepare B_1
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*/
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if (a_total >= UINT32_MAX) {
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RSSVAL(ctx->B_i, 0, 0xFFFF);
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RSBVAL(ctx->B_i, 2, (uint64_t)a_total);
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ctx->B_i_ofs = 10;
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} else if (a_total >= 0xFF00) {
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RSSVAL(ctx->B_i, 0, 0xFFFE);
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RSIVAL(ctx->B_i, 2, a_total);
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ctx->B_i_ofs = 6;
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} else if (a_total > 0) {
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RSSVAL(ctx->B_i, 0, a_total);
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ctx->B_i_ofs = 2;
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}
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ctx->S_i_ofs = AES_BLOCK_SIZE;
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}
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void aes_ccm_128_update(struct aes_ccm_128_context *ctx,
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const uint8_t *v, size_t v_len)
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{
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size_t *remain;
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if (ctx->a_remain > 0) {
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remain = &ctx->a_remain;
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} else {
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remain = &ctx->m_remain;
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}
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while (v_len > 0) {
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size_t n = MIN(AES_BLOCK_SIZE - ctx->B_i_ofs, v_len);
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bool more = true;
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memcpy(&ctx->B_i[ctx->B_i_ofs], v, n);
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v += n;
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v_len -= n;
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ctx->B_i_ofs += n;
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*remain -= n;
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if (ctx->B_i_ofs == AES_BLOCK_SIZE) {
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more = false;
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} else if (*remain == 0) {
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more = false;
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}
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if (more) {
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continue;
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}
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aes_ccm_128_xor(ctx->X_i, ctx->B_i, ctx->B_i);
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AES_encrypt(ctx->B_i, ctx->X_i, &ctx->aes_key);
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ZERO_STRUCT(ctx->B_i);
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ctx->B_i_ofs = 0;
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}
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}
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static void aes_ccm_128_S_i(struct aes_ccm_128_context *ctx,
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uint8_t S_i[AES_BLOCK_SIZE],
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size_t i)
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{
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uint8_t A_i[AES_BLOCK_SIZE];
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A_i[0] = L_;
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memcpy(&A_i[1], ctx->nonce, AES_CCM_128_NONCE_SIZE);
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RSIVAL(A_i, (AES_BLOCK_SIZE - AES_CCM_128_L), i);
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AES_encrypt(A_i, S_i, &ctx->aes_key);
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}
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void aes_ccm_128_crypt(struct aes_ccm_128_context *ctx,
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uint8_t *m, size_t m_len)
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{
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while (m_len > 0) {
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if (ctx->S_i_ofs == AES_BLOCK_SIZE) {
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ctx->S_i_ctr += 1;
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aes_ccm_128_S_i(ctx, ctx->S_i, ctx->S_i_ctr);
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ctx->S_i_ofs = 0;
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}
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m[0] ^= ctx->S_i[ctx->S_i_ofs];
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m += 1;
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m_len -= 1;
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ctx->S_i_ofs += 1;
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}
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}
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void aes_ccm_128_digest(struct aes_ccm_128_context *ctx,
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uint8_t digest[AES_BLOCK_SIZE])
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{
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uint8_t S_0[AES_BLOCK_SIZE];
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aes_ccm_128_S_i(ctx, S_0, 0);
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/*
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* note X_i is T here
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*/
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aes_ccm_128_xor(ctx->X_i, S_0, digest);
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ZERO_STRUCT(S_0);
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ZERO_STRUCTP(ctx);
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}
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