50 lines
887 B
C
50 lines
887 B
C
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/*
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* Copyright (c) 2020, yzrh <yzrh@tuta.io>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include "cnki.h"
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int
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cnki_kdh(cnki_t **param)
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{
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if (*param == NULL)
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return 1;
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if ((*param)->stat > 0)
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printf("Begin 'KDH' decryption\n");
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fseek((*param)->fp_i, 0, SEEK_END);
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long size = ftell((*param)->fp_i);
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fseek((*param)->fp_i, ADDRESS_KDH_BODY, SEEK_SET);
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const char key[] = KEY_KDH;
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const int key_len = KEY_KDH_LENGTH;
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long key_cur = 0;
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char buf[(*param)->size_buf];
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for (;;) {
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fread(buf, (*param)->size_buf, 1, (*param)->fp_i);
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for (int i = 0; i < (*param)->size_buf; i++) {
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buf[i] ^= key[key_cur % key_len];
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key_cur++;
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}
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fwrite(buf, (*param)->size_buf, 1, (*param)->fp_o);
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if (ftell((*param)->fp_i) == size)
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break;
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}
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if ((*param)->stat > 0)
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printf("Decryption ended total %ld byte(s) written\n",
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ftell((*param)->fp_o));
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return 0;
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}
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