73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
#include "sm4_core.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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struct ctr_state {
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unsigned char ivec[SM4_BLOCK_SIZE];
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unsigned char ecount[SM4_BLOCK_SIZE];
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unsigned int num;
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};
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static void rk_init_ctr(struct ctr_state *state, const unsigned char *iv) {
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state->num = 0;
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memset(state->ecount, 0, SM4_BLOCK_SIZE);
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memcpy(state->ivec, iv, SM4_BLOCK_SIZE);
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}
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/* increment counter (128-bit int) by 1 */
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static void rk_ctr128_inc(unsigned char *counter) {
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unsigned int n = SM4_BLOCK_SIZE;
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unsigned char c;
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do {
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--n;
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c = counter[n];
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++c;
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counter[n] = c;
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if (c)
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return;
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} while (n);
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}
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static void rk_crypto_ctr128_encrypt(void *ctx, const unsigned char *in,
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unsigned char *out, unsigned int len,
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unsigned char *ivec,
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unsigned char *ecount_buf,
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unsigned int *num, block128_f block) {
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unsigned int n, l = 0;
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n = *num;
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while (l < len) {
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if (n == 0) {
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(*block)(ivec, ecount_buf, ctx);
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rk_ctr128_inc(ivec);
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}
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out[l] = in[l] ^ ecount_buf[n];
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++l;
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n = (n + 1) % SM4_BLOCK_SIZE;
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}
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*num = n;
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}
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int rk_sm4_ctr_encrypt(const unsigned char *in, unsigned char *out,
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unsigned int length, const unsigned char *key,
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const int key_len, unsigned char *ivec, const int enc) {
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sm4_context ctx;
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struct ctr_state state;
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if (key_len != 16)
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return -1;
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if (length == 0)
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return -1;
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rk_init_ctr(&state, ivec);
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rk_sm4_setkey_enc(&ctx, key);
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rk_crypto_ctr128_encrypt((void *)(&ctx), in, out, length, state.ivec,
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state.ecount, &state.num, rk_rk_sm4_crypt_ecb);
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return 0;
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}
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