76 lines
1.5 KiB
C
76 lines
1.5 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "sm4_core.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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{
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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) 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, unsigned char *out,
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unsigned int len, unsigned char *ivec, unsigned char *ecount_buf,
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unsigned int *num, block128_f block)
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{
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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, const int key_len,
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unsigned char *ivec, const int enc)
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{
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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,
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state.ivec, state.ecount,
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&state.num, rk_rk_sm4_crypt_ecb);
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return 0;
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}
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